Solenoid valve, Servos and Intelligent Transduction

If you're looking for good servo solenoid valve, you'd be pressed to find a better brand than Parker solenoid valve or its subsidiaries, most of whom sell Parker's products, identical but for repackaging. Parker solenoid valve are used for motion control in a vast number of industries - so vast a number, actually, that entering any large scale factory or production facility is bound to bring you into contact with machines that contain at least a few of the company's products.

Servo solenoid valve and servo motors are, to mince no words, absolutely crucial to the process of intelligent automation. We say 'intelligent' because servo solenoid valve are designed in such a way that they can respond to stimuli - so that, in some way, the condition of the whole machine is sensed by the servo, a sense to which the device then adjusts its operation accordingly.

An example of this technology of transduction, as it's called, can be found in cars that utilize cruise control. Cruise control systems usually estimate the ground speed of a car by the speed of the rotation of the car's driveshafts. On the basis of that information, cruise control systems change or maintain the position of the throttle by means of a solenoid (the same kind used in solenoid solenoid valve).

Thus for a device to be a servo, be it a valve or a motor, it needs to perform some kind of error correction in response to outside conditions. Another example was the earliest incarnation of the world famous thermostat, which was designed and patented by one Albert Butz in 1886. This device was designed in such a way that when a room's temperature fell below a certain level, the device would close a circuit and in so doing energize a solenoid which would suck in its armature, allowing the main motor shaft to turn one half revolution, pulling a chain connected to its crankshaft which in turn would open the furnace grate wider, allowing air to enter, giving the flames more oxygen to feed on. Once the temperature rose above a certain level, the solenoid would energize again, allowing the engine to turn another half revolution, pulling the chain back and closing the grate.

Parker solenoid valve are generally very sophisticated systems of this nature, all utilizing in some way the guiding concept of negative feedback - the means by which the desired or 'control' position of the device is contrasted with the actual position, and the 'negative' difference adjusted for.

The majority of electrohydraulic solenoid valve (an electromechanically enable form of hydraulic valve) are servo solenoid valve, as well as being, technically speaking, solenoid solenoid valve. Their response is to the pressures at play on the valve. By various means, usually computerized, Parker solenoid valve can calculate the pressure bearing down on their intake pipes and thus calculate the adjustment necessary to allow the appropriate amount of fluid through when desired.

Hydraulic solenoid valve of this nature are capable of actuating a great deal more force than solenoid solenoid valve or pneumatic solenoid valve. However, because liquids are incompressible relative to gases, hydraulic Parker solenoid valve are generally reinforced to a far greater degree than pneumatic mechanisms, to ensure that the machine doesn't break under the onslaught of its own strength.

EGR and Electric Vacuum solenoid valve

Electric vacuum solenoid valve perform an environmentally and economically important function in the engines of most cars.

First off, the fact that electric vacuum solenoid valve prevent unburned fuel particles and several other forms of gaseous and particulate waste that engines produce from escaping into the air and thence to the atmosphere means that cars without them are bound to leave you with a very swollen-looking carbon footprint.

Secondly, the fact that the exhaust gas recirculation (EGR) systems of cars that require electric vacuum solenoid valve or switching solenoid valve raise fuel efficiency is a great boon to just about anyone these days. With fuel prices soaring higher by the day, every little bit, even teeny-weeny particles and gas-huffs, really does count.

EGR solenoid valve work by the sucking up of exhaust gases before they can leave the car. Very frequently, they're activated by an increase in the vacuum produced by the engine, a factor that's directly proportional to how hard the engine is exerting itself. When the valve's transduction mechanism gets activated in this way, the electric vacuum solenoid is also activated, and the valve opens, allowing exhaust gases to return to the intake manifold, which normally has the pleasing side effect of cooling the cylinder.

The switching solenoid at work in an EGR system is the same as any other solenoid - an unimpressive-looking spool of engine wire (often wound up to a thousand times) which, when it has a current passed through it, produces an electromagnetic field. This field will, depending on the direction in which the wire coils, either produce a suctioning, 'pulling' force or a repulsive, 'pushing' force on any object placed within it.

Solenoid valve just like the electric vacuum solenoid appear in several other parts of your car. There's one connected to your car's ignition and, when you turn the key, for the car to grumble to life the starter solenoid has to move two heavy contacts together. When those contacts meet, they allow electricity to chart a straight course from the car's battery to the engine, thus starting the car.

The principle in operation with starter solenoid valve is similar in some ways to how most solenoid solenoid valve work, the only difference being that, where solenoid valve are concerned, you're dealing with the flow of liquid or gas, not electricity, and that often the movement of the solenoid is to remove it from being a barrier to the flow, not to bring two conduits together. Simply described, the 'pin' that blocks the secondary conduit between the pressurized central chamber and the outlet of the valve is actually the armature of the solenoid.

When removed, pressure is immediately reduced in the central chamber, allowing the burgeoning pressure pushing against the diaphragm blocking the central chamber from the entry conduit to push the diaphragm up. This then allows for a straight flow of air or liquid to run from the inlet to the outlet of the solenoid valve.

As soon as the armature pin is replaced, pressure builds up again in the central chamber, and the force of the fluid allowed to flow through the tiny hole in the centre of the diaphragm builds up sufficiently to push the diaphragm back into place, closing the solenoid valve.

Control Solenoid Valve Capable of Producing an Output of Working Fluid

Festo launches a new series valve jet, said extremely fast switching time of less than 1 ms - an order of magnitude faster than the standard setting solenoid valve. Based on a new design with only one moving part,high pressure filters the new set of valve jet MHJ is also very high switching time,propane high pressure regulator repeatability, and claimed to have been a sign of life 10 billion.

The jet valve adapted to different applications of sorting a large volume, particularly in food processing and recycling industry. Festo valve jet HJ series is designed for use with 40um standard designed filtered air, and host a wide range of operating pressures of 0,5 bar at 6. They offer a choice of three switching 2/2-way model quickly with flow rates of 50, 100 and 150 liters per minute.

The valves use a special short plate valve developed and patented a decay CAE full modeling of magnetic tape in order to optimize the temperature and flow behavior changes its characteristics. To go so fast, that offers long life, the new design does not require dynamic seals and lubrication. The design of the magnetic coil and amortization flat plate also allows the valve to the constant replay of the conversion is less than 0,1 ms for the duration of specialist machinery for the sorting is necessary.

HJ Jet Series valves have a voltage range of the signal starts from 3 to 30V DC, to receive the standard 5V PLC signals without the need to convert the voltage. The valves have a power consumption of 7W, which can be reduced to 2W, the first time using a switch control fixture that can be provided by Festo is embedded in the coil assemblies or within Council control applications.

Festo HJ Jet Series valves are available in single units with an integrated and accessories can be provided on the structure of the sliding plate with sub-bases. Festo also produces custom headers that allow groups of air valves with the same hand that can be fixed nozzle, if necessary.

As is well known in the art, control valves have frequently been used to control and supply a working fluid, such as air, to a working device. Typically, these control valves employ a moveable valve spool disposed in a valve housing. The valve housing includes a plurality of fluid passages that are selectively interconnected in response to movement of the valve spool so as to control the flow of the fluid and, thus, the output of the control valve.

Conventional control valves often employ a solenoid valve mounted thereto for actuating the valve spool. The solenoid valve is controlled via an electrical input signal between a first position, where the solenoid valve is de-energized so as to close a fluid passage between an input pilot pressure and an output controlling pressure and to open the outlet to atmosphere, and a second position, where the solenoid is energized via the electrical input so as to open a passageway between the input pilot pressure and the output controlling pressure and block the fluid passage from outlet to exhaust.

It should be readily appreciated to one skilled in the art that in order to apply a constant controlling pressure, the electrical control signal must continue to energize the solenoid valve. That is, in order for a conventional control valve to maintain the spool in a predetermined position, it is necessary to maintain a constant control pressure upon one side of the spool. Therefore, in order to maintain this constant control pressure on the spool, it is necessary to maintain the solenoid valve in an opened and, thus, energized state. Moreover, it is necessary to employ full line fluid pressure to displace and maintain the working device in a predetermined position. Therefore, it will be understood that operating a device at full line pressure requires more energy to drive compressors than operating the device at a reduced line pressure.

Accordingly, there exists a need in the relevant art to provide a control solenoid valve capable of producing an output of working fluid to be used with a conventional working device that is capable of minimizing the energy consumed during actuation. Furthermore, there exists a need in the relevant art to provide a control valve that maintains the position of a control element at a pressure less than full line pressure. Still further, there exists a need in the relevant art to overcome the disadvantages of the prior art.

Solenoid Valve Control Unit for Hygienic Applications

The Thinktop Stainless air treatment units platform no-touch-and hydraulic solenoid valve set-and-forget functions eliminate mechanical sensor adjustments.

LEDs on the unit constantly display the status of the automatic valve (valve positions stored, solenoids de-energized, Setup in progress and local fault indication).

The installation should be a straightforward procedure, no special skills or expensive adapters are required.

Connected to a network cable, and configured with a unique node address is the initial setup of the sensor board is carried out manually with a quick five-touch process.

The process operator not only saves time during installation and project costs but also reduces the life-cycle costs.

The Basic Thinktop The modular design makes them for the migration, upgrade and expansion of existing facilities.

The new Basic Thinktop meets the IP66 and IP67 standards for protection of electronic equipment against the ingress of dust and liquids.

It simplifies installation and reduces engineering, hardware, preliminary testing and commissioning costs.

The new Basic Thinktop unit provides automated control and monitoring of sanitary fittings.

Based on the Thinktop Sensing and Control Unit is the version that said ideal for use in all sanitary applications and is compatible with all popular logic controller and the master gateway to the specification version 3.0.

The extension of v3.0 includes the basic platform Thinktop 62 knots.

Mounted on the sanitation drive an Alfa Laval fitting covers offer the Basic Thinktop a sensor board and solenoid valve for automated control and monitoring of every connected valve.

Structural principle of solenoid valve

Are normally closed and normally open type two. Normally closed when power was turned off, when the solenoid valve force generated when the coil power, so moving core to overcome the spring force directly with the static pull open the solenoid valve core, medium was access; When the coil power disappear when the solenoid force, an iron core under the action of the spring force reduction, direct closure of solenoid valve ports, media barrier. Simple structure and reliability, at zero pressure and micro-vacuum work. Normally open type just the opposite. If less than φ6 flow path of the solenoid valve.

step-type solenoid valve direct-acting

The valve is an open valve and open valve connected to the second one, the main valve and valve-step guide to direct the solenoid force and the pressure to open the main valve port. When the coil is energized, the solenoid force to moving core and static core pull, pilot valve open while the pilot valve mouth port located on the main valve port, and the moving core and the main spool together, this time the main valve the pressure chamber through the pilot valve port of unloading, the pressure difference and the effect of solenoid forces while the main spool to move upwards.

Open the main valve medium flow. When the coil power disappear when the solenoid force, this time moving core in the role of gravity and spring force to shut down pilot valve hole, then the balance hole in the medium into the main valve on the chamber, so that the chamber pressure increases, at this time In the spring under the pressure reset and close the main valve, medium stop. Reasonable structure, reliable action, when the work at zero pressure and reliable. Such as: ZQDF, ZS, 2W.

Indirect Pilot solenoid valve

This series solenoid valve by the pilot valve and main solenoid valve connected with the formation of channel combinations; normally closed when without power, was switched off. When the coils, the magnetic force generated by moving core and static iron core to pull, guide valve port open, medium flow to the export, then the main valve on the chamber pressure decreased, the pressure below the import side, the formation of pressure to overcome the spring resistance and the resulting upward movement, to open the main valve port of purpose, medium flow.

When the coil power, the magnetic force disappears, moving core in the spring force reduction and closure of the pilot under the mouth, this time from the balance hole into the medium, the main solenoid valve on the chamber pressure, and under the action of the spring force downward, close the main solenoid valve port. Often the opposite of open principles. Such as: SLA, DF (φ15 above caliber), ZCZ so.

Selection of the solenoid valve principle

A solenoid valve is a coil of wire that becomes magnetized when electricity is run through it. Solenoids often have a hole in the middle and a protruding metal rod that is pushed or pulled by magnetism when power is applied. A solenoid valve uses a solenoid to actuate a valve. This lets you control the flow of water, air, or other things with electricity.

There are many different types of solenoid valves available, and many companies that make them. When selecting a solenoid valve, you must pay attention to:

1.Coil voltage, current, AC or DC, and intermittant versus continuous duty.

2.valve type

3.aperture size

4.pressure rating, such as "50 PSI"

5.materials (medium) that it can control, such as "air/water"

6.type of connection to each port, such as "1/4" NPT"

Fluid pipe valve must be selected in the calibration of medium range model consensus. Fluid temperature must be less than the calibration temperature selection valve. Solenoid valve to allow liquid viscosity generally 20CST less than 20CST should be marked.

Working pressure, maximum pressure pipeline should be used in less than 0.04MPa as ZS, 2W, ZQDF, ZCM series direct-action direct-action and step; minimum working pressure greater than 0.04MPa may use Pilot (Pressure Differential) solenoid valve; maximum working pressure should be less than the maximum calibration pressure solenoid valve; generally one-way valve is working, so pay attention to whether there is anti-pressure, if installed check valve.

Fluid cleanliness is not high solenoid valve should be installed before the filter, the general solenoid. Valve cleanliness requirements of the media better.

Note flow aperture and take over the aperture; solenoid valve generally only two control switches; conditions allow, install bypass pipes, easy maintenance; a water hammer phenomenon to customize the opening and closing time of valve adjustment.

Pay attention to environmental impact of temperature on the solenoid valve

Supply current and power consumption should be selected according to the output capacity of the power supply voltage ± 10% around the general permit, must pay attention to when starting the exchange value of the higher VA.

Second, reliability

Solenoid valve normally closed and normally open divided into two; generally used in the normally closed, power open, power off; but in a very long time to open a very short time to close the normally open type of use.

Life testing, factory type test items are generally, not specifically our professional standards solenoid valve, so use caution when solenoid valve manufacturers.

Action is very short at high frequencies usually select direct-acting type, rapid series of large diameter selected.

Third, security

General solenoid valve is not waterproof, when the conditions are not allowed to use water when you type, the factory can be customized.

The maximum calibration nominal pressure solenoid valve must be more than the maximum pressure within the pipe, otherwise life will be shortened or produce other surprises.

Corrosive liquids should be used all stainless steel type, strong corrosive fluids should use plastic Wang (SLF) solenoid valve. Explosive environments must be selected corresponding proof products.

Fourth, economy

There are many solenoid valve can be generic, but meet the above three points should be chosen based on the most economical product.

Revolutionary Solenoid Valve Actuator Reduces Valve Installation Costs By Up To 50%

Ningbo Lida Pneumatic Complete Sets Co.,Ltd., a manufacturer of valve operating solutions and solenoid valve actuators, announces a revolutionary actuator design that achieves dramatic cost reductions in the installation of valves used in hazardous environments. The patented Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator reduces installation cost by almost 50% in intrinsically safe (IS) installations, and by almost 20% in explosion proof (EX) installations.

"The high cost, complexity and poor reliability of traditional valve actuator solutions led our engineers to look for a simple, cost effective solenoid valve solution," said Robert Altonji, President of Ningbo Lida Pneumatic Complete Sets Co.,Ltd. LLC. "The end result is our Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator, a pneumatic magnetic replacement for OEM coils on direct acting solenoid valves."

The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator's U.S.-patented design is a complete, self-contained pneumatic magnetic device that provides the same powerful on/off magnetic field as the original coil. It is unique in five ways:

Unlike typical pneumatic actuators, its use is not restricted to factory-built pneumatic valves. Rather, it can be used as a direct drop-in replacement for the OEM coil on any direct acting solenoid valve. The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator is fully compatible with any original hermetically sealed valve.

The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator substantially reduces the cost of valve installations in hazardous environment. Valves converted to Ningbo Lida Pneumatic Complete Sets Co.,Ltd. are operated by an inexpensive air pilot using a small diameter, flexible pneumatic line. No field wiring, conduit, or intrinsically safe (IS) barriers and no electricity at the valve are required.

The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator's sealed design, combined with the fact that it works with hermetically sealed (packless) direct acting valves, allows it to offer extremely high reliability.

By essentially converting solenoid valves to pneumatic valves, Ningbo Lida Pneumatic Complete Sets Co.,Ltd. technology dramatically expands the variety of valves available to the user.

The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator is less bulky than either pneumatic rotary actuators or pneumatic valves, reducing space requirements.

Speaking to the dramatic cost reduction inherent to Ningbo Lida Pneumatic Complete Sets Co.,Ltd.'s solution, Altonji said "Direct acting solenoid valves require wiring and conduit installations that meet national and local codes. These requirements are typically several times the cost of the valve."

Altonji noted that in hazardous installations including explosion proof (EX) and intrinsically safe (IS), this cost and complexity can be avoided if direct acting solenoid valves are converted to operate with the Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator.

"Traditional electric installations require extensive material, labor, space, and time to install" said Altonji. "When compared with explosion proof (EX) or Intrinsic Barrier (IS) designs, the Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator offers the lowest installed cost".

The Ningbo Lida Pneumatic Complete Sets Co.,Ltd. Actuator is available for use with a wide range of valves including ASCO?, SMC USA and Parker-Skinner solenoid valves.

ASCO? is a registered trademark of ASCO? Valve, Inc. - All other brand names, product names or trademarks belong to their respective holders.

About Ningbo Lida Pneumatic Complete Sets Co.,Ltd.

Ningbo Lida Pneumatic Complete Sets Co.,Ltd. designs and manufactures cost-saving and performance-enhancing products for the valve industry. Ningbo Lida technology is covered under US Patent #6,991,211. International patents are pending.

Solenoid valves: Operation, selection, and application

A full understanding of solenoid valve and some selection and installation tips will help to avoid trouble and provide an optimum application.

Solenoid construction

There are two types of solenoid valve construction: hermetic and take-apart.

Hermetic valves are brazed or welded together at the factory and have the advantage of being inherently free of external leaks.

Hermetic construction is most common in valves having a port size of 1/2 in. or less. Hermetic valves, of course, cannot be disassembled for cleaning or repair.

Take-apart types can be serviced and repair kits are normally available from the manufacturer. Some form of seal, usually elastomer gaskets or O-rings, is required.

This produces the potential for leakage after a period of service, particularly when prolonged high temperatures are encountered. The variety of refrigerants and lubricants now used results in a difficult application for seal materials.

Also, formulas published by O-ring manufacturers indicate that permeability directly through the seal material can account for as much as 0.25 oz/year of refrigerant loss in a medium- to large-size valve.

Piloted or directly operated

Valves with a small port, or those that have to operate at only a limited pressure differential, are usually actuated directly by the solenoid plunger. The magnetic pull generated by the coil windings is used to operate the main valve pin, or poppet, directly.

A directly operated solenoid is illustrated in Figure 1.

The force required is simply the port area multiplied by the maximum operating pressure differential. For refrigeration service, a pressure differential of at least 300 psi is usually needed. This limits the port diameter to about 1/8 in.

A trick sometimes used to increase the maximum pressure differential is the addition of free play, or travel, between the plunger and valve pin. This permits the plunger to start in flight and gain momentum before attempting to lift the valve pin from the port.

This is referred to as a "hammer blow" design.

Pilot-operated valves can be made with very large main ports, because the magnetic pull is used only to operate a small pilot port. Figure 2 shows a pilot-operated valve with a diaphragm-type main valve element.

The flexure of the diaphragm allows the main poppet to lift from the main port. The diaphragm has a small hole located so that valve inlet pressure is bled to the top of the diaphragm.

As long as the pilot valve is closed, inlet pressure is exerted on the top side of the diaphragm, and the main poppet is held tightly on the valve seat by the pressure differential between inlet and outlet.

When the pilot valve is opened, pressure above the diaphragm is exhausted to the valve outlet, and inlet pressure on the underside of the diaphragm causes the main valve to lift from the port. Since there is usually a return spring urging the main valve closed, a minimum pressure differential between valve inlet and outlet may be required to maintain the valve fully open against the spring load.

Most pilot-operated valves require minimum pressure drop to provide stable, full-open operation. Special models are sometimes offered for "zero-differential" pressure. These may use an external pressure source as the actuating power.

Some designs use a piston instead of a diaphragm. The piston has a small bleed hole, and operation is the same as a diaphragm valve. When the pilot exhausts pressure from above the piston, inlet pressure causes it to lift, opening the main port. Figure 3 shows a piston valve.

This very simple arrangement is often used on valves of 7/16-in. port size or less.

There is a basic size limitation for this design, since the pilot valve plunger must travel slightly farther than the piston stroke. If the plunger stroke is too long, the magnetic pull is greatly reduced.

The focus of the foregoing has been on two-way valves but, of course, other varieties of solenoid valves are available and the same basic principles apply. These other varieties include three- and four-way and normally open valves.

The larger sizes use a pilot valve to generate a pressure unbalance, causing the main valve to lift or slide.

Valve selection

Valves should not be selected by line size. The maximum allowable pressure drop should be determined from system requirements.

For example, a low-temperature refrigeration system may not tolerate more than a 0.25-psid pressure drop in a suction line solenoid. A hot gas defrost valve for the same system would probably be sized to pass the requisite flow at a pressure drop of near high- to low-side differential — perhaps 150 psid.

Published capacity data should always be used for size selection. It is important to avoid oversizing a piloted valve such that the minimum allowable operating pressure drop does not develop. This may cause the valve to chatter, "chug," or fail to open fully.

If there is a minimum operating pressure differential limit, it will be published along with other valve data.

It is also important not to exceed the maximum operating pressure differential (MOPD) between inlet and outlet. By safety agency requirements, solenoids must be able to operate at their MOPD rating at 85% of rated line voltage. The same valve typically has a lower MOPD when a direct current coil is used.

Valves must also have a maximum rated pressure (MRP) of at least the maximum pressure expected on the application. The MRP is the maximum internal pressure to which the valve may be subjected as specified by the manufacturer.

Use valves only with the fluids they were designed to handle, since internal materials may be incompatible with other fluids. Also, do not use a general-purpose valve for shutting off of combustibles, such as natural gas or propane. These applications require a solenoid valve that has met special safety agency requirements for "safety shut-off service."

Coil housings

Most solenoids are available with a variety of coil housing types. The proper type depends on the exposure to the elements, and the degree of protection afforded by the enclosure in which the valve is installed.

Coil housing types are designated by ANSI/NEMA (American National Standards Institute/National Electrical Manufacturers Association) standards as suitable for certain applications. In general, the higher the ANSI/NEMA type number, the greater the exposure to the elements that can be permitted.

For example, NEMA Type 1 is suitable for most indoor applications, while NEMA Type 4 is suitable for most outdoor applications. For locations where there are explosive vapors or dust, special explosion-proof housings, designated NEMA Type 7 or Type 9, are required. Usually, both conduit and junction box styles are available, as well as European DIN styles.

A complete treatment of ANSI/NEMA and safety agency standards is well beyond the scope of this article. For help in selecting the appropriate coil housing for the exposure expected, the manufacturer's literature or application engineering department should be consulted.

Electrical ratings and performance

In addition to voltage and frequency, specifications include holding current and inrush current as well as wattage.

Inrush is the current that prevails immediately after the switch is closed, but before the plunger has completed its travel.

The current draw of ac coils is determined by coil impedance, not resistance alone. Impedance results from a combination of resistance and inductive reactance.

Inductive reactance is a measure of how much the flow of current is inhibited as a result of the rapidly reversing magnetic fields associated with an alternating current. Inductive reactance increases both with frequency and with the amount of iron in the core of the solenoid. This is why current draw is higher at 50 Hz than at 60 Hz. It also explains why inrush current is often twice as high as holding current.

When the switch is first closed, the plunger is at some distance from the stationary pole, so that an air gap greatly limits the magnetic field strength. After the plunger reaches its final position, the air gap is closed and the effectiveness of the iron in the core is much greater.

This causes the inductive reactance, and therefore the impedance, to be much higher after the plunger completes its flight and solidly contacts the stationary pole.

Current in a dc solenoid depends only on resistance, so inrush and holding current are no different. This is why the MOPD rating is lower with direct current; there is no benefit of initial over-current to assist in lifting the plunger.

Recently, electronically enhanced dc coils have been developed which artificially produce an over-current for the first few milliseconds, simulating the inrush current of ac and providing full MOPD.

Installation

The instruction sheet that comes with the valve is the best authority on installation, but here are a few points worth emphasizing.

Take-apart valves with extended copper tubes are designed to be brazed without disassembly, with proper wet-ragging procedures. This is preferred, since valves are leak tested at the factory and the possibility of a leak developing during field reassembly is eliminated. Also, no parts can be lost or misassembled.

If a valve is equipped with a manual-opening stem, be sure to open it during a nitrogen brazing purge and subsequent evacuation. Also, in some designs, having an elastomer or plastic seat material out of contact with the hot valve body during brazing provides an added margin of safety from heat damage.

For an ac coil that is not installed on a valve, never apply power for more than a few seconds. As noted earlier, current draw is greatly influenced by the amount of iron in the solenoid core. When the coil is uninstalled, there is no iron and current can be as much as four times' normal.

It is recommended that valves not be installed with the plunger enclosing tube (coil tube) angled down below the horizontal. The reason is that system debris can collect in the tube, preventing proper magnetic contact between the plunger and the stationary pole piece in the top. This can cause coil buzz and excessive current draw.

Troubleshooting

Again, the valve instruction sheet usually gives troubleshooting tips, but here are some causes of trouble that may be more elusive.

Under-voltage as well as over-voltage can cause coil burnout, the same as a motor. Also, pressure differentials that are too high for the valve to open against can cause coil burnout, because current draw tends to remain near the inrush value.

Make sure that the design pressure drop is always at least equal to the minimum differential that the valve is rated for.

An oversized solenoid valve of the piloted type may behave strangely at some operating conditions, where there is insufficient pressure differential to open it or maintain it in a stable open condition. In these cases the valve may chug or chatter, or may seem to open just partially, producing a very low flow.

Diagnosing and curing a sick solenoid valve

Solenoid valve is reliable and fairly simple devices in a refrigeration system, and for the most part a very healthy component.

But when solenoid valves do, in fact, experience a malfunction, the best way to a quick recovery is to first identify symptoms of the problem, then carefully examine possible causes. Here are some tips.

There are four symptoms that indicate a solenoid valve is malfunctioning. They include:

1.Failure to open;

2.Failure to close;

3.Internal or external leakage; and

4. Creating noise when energized.

So what causes these ailments? Follow this technical advice for diagnosing symptoms of an unhealthy solenoid valve and treating it properly for a quick recovery.

Symptom: valve won't open

When energized, a normally closed solenoid valve opens (see Figures 3 and 4). When the solenoid is energized, the plunger strikes the pole piece with an audible "click." If you don't hear a click, the valve isn't working properly.

Diagnosis: Electrical or mechanical failure.

Remedy: First, be sure that there is a completed electrical circuit. Voltage to the coil should be at least 85% of the rating shown on the valve's nameplate.

If proper voltage is measured at the coil and you still don't hear a click, then a mechanical obstruction is preventing the plunger from moving. The obstruction may be caused by overpressurization, dirt, or worn components.

Next, check the pressure at the valve inlet to ensure that it doesn't exceed the maximum operating pressure differential (MOPD) as rated on the valve's nameplate.

If dirt is present in the system, disassemble and clean the valve and install a suitable filter upstream from the valve.

Important: Remember to evacuate the system or isolate the valve from the system's refrigerant before disassembling. Also, it's important to replace worn components with the correct manufacturer's rebuild kit.

Pilot-operated diaphragm or piston valves may fail to open if system pressure is below the minimum pressure differential requirement stated on the valve's nameplate.

In addition, if the diaphragm or piston pilot orifice (which controls the opening of the valve) is blocked by dirt or debris, pressure will remain above the diaphragm or piston, and the valve will not open. (The pilot orifice in offset pilot valves is located in the valve body, directly below the plunger.)

A torn diaphragm also allows too much pressure above the diaphragm, causing it to remain closed.

Symptom: valve won't close

Diagnosis: Electrical or mechanical failure.

Remedy: When a de-energized valve won't close, again, check the electrical circuit to ensure that power is disconnected from the coil. Mechanical causes that inhibit movement of the plunger, including a missing or damaged plunger return spring, may not allow the plunger to seal off the main orifice or pilot orifice.

In the case of pilot-operated diaphragm or piston valves, a blocked bleed orifice can cause the valve to remain open.

When encountering "failure-to-close" characteristics, it is important to know whether the valve isn't closing at all, or if it is attempting to close but doesn't close completely because of internal seat leakage. In the case of internal seat leakage, other causes should be considered.

Symptom: valve won't open (normally open)

Diagnosis: When a normally open, de-energized valve won't open, it's an electrical or mechanical failure.

Remedy: A normally open valve should open when it's de-energized. If it doesn't, overpressurization, dirt, or worn components may be at fault.

In this case, check the electrical circuit to ensure that power has been disconnected from the coil.

Symptom: valve won't close (normally open)

Diagnosis: The bleed orifice controls the closing for the energized valve and, if blocked, will not allow pressure to flow above the dia-phragm or piston, enabling them to close the valve.

Remedy: A normally open valve should close when energized. Similar electrical causes to those identified under the "fails to open when energized" category should be considered.

Additionally, when examining pilot-operated diaphragm or piston valves, the bleed orifice in the diaphragm or piston should be inspected.

Symptom: internal seat leakage

Diagnosis: Internal seat leakage can be caused by debris that restricts the plunger disc or diaphragm from sealing completely on internal orifices.

Deterioration of valve orifices or sealing materials, caused by wear or media incompatibility, also are possible causes of internal leakage.

Remedy: Pilot-operated valves, which require a minimum pressure differential to operate, may not seal off tightly, causing internal leakage if system pressure is less than the rated minimum pressure required.

Symptom: external seat leakage

Diagnosis: External leakage can be caused by missing or damaged external seals. Seals can be damaged by:

System media that is incompatible with the seals;

Overpressure that causes the seals to dislodge; or

Incorrect reassembly (if the valve has been disassembled).

Be sure to refer to the manufacturer's installation and maintenance instructions for correct brazing, disassembly, and torque specifications.

Improper installation also may cause external leakage.

Remedy: When installing mechanical connections to a solenoid valve, use a second wrench on the valve body for support so that the body won't be distorted. Never use the valve plunger tube or solenoid as a lever to provide support.

When brazing, be sure to wrap the valve in a wet rag (extended-end versions), or disassemble the valve if sweat connections are not extended-end versions.

Symptom: noise when energized

Diagnosis: Ac voltage solenoid valves may emit a slight hum when energized. This is typical because of the magnetic wave form caused by ac voltage. If this noise becomes excessive, however, there may be missing components from the solenoid assembly, or an incomplete magnetic circuit.

Remedy: To complete the magnetic circuit, the plunger must make contact with the pole piece. Debris in the plunger enclosure tube, a worn plunger (or pole piece), damaged enclosure tube, or damaged plunger return spring may prevent the plunger from making contact with the pole piece.

Supply voltage lower than 85% of the nameplate rating may be insufficient to overcome the plunger return spring force. Noise will result.

Sidebar: Take the quiz!

1. If proper voltage is measured at the coil and you still don’t hear a click, then a mechanical obstruction is preventing the plunger from moving. The obstruction may be caused by (underpressurization, overpressurization); dirt; or worn components.

2. A torn diaphragm also allows (too much, too little) pressure above the diaphragm, causing it to remain closed.

3. The bleed orifice controls the (closing, opening) for the energized valve and, if blocked, will not allow pressure to flow above the diaphragm or piston, enabling them to close the valve.

4. Pilot-operated valves require a (minimum, maximum) pressure differential to operate.

5. Supply voltage lower than (65%, 85%, 95%) of the nameplate rating may be insufficient to overcome the plunger return spring force. Noise will result.

Symptom: short coil life

Diagnosis: Excessive heat is typically the cause of short coil life. Heat can be generated by media temperature, ambient temperature, excessive voltage, or an incomplete magnetic circuit.

Remedy: Care should be taken to specify a coil insulation system capable of withstanding the various operating temperatures. Never energize a coil when it isn't in the plunger tube.

Most solenoid coils today are epoxy or plastic encapsulated. However, if a tape-wound coil is used, moisture or dust may cause premature failure.

Altogether, solenoid valve is reliable and easy to maintain. If they are installed properly and inspected thoroughly in a regular maintenance program, they should operate efficiently and with few problems.

Lida manufacturer expands piston air-operated solenoid valve line

Lida provider of pneumatic components and solenoid valve systems for elevated pressure applications High Pressure Equipment Company, which distributes locally through provider of electrical, mechanical, process measurement, process control and solenoid valve automation technology Variable Process Solutions, has added to its extra-heavy-duty Hippo piston air-operated solenoid valve line.

The line has been extended with new orifice sizes, maximum opera-ting pressures and air pressures. These piston air operators provide remote automatic on/off valve operation in maximum operating pressures of 690 bar, 1 380 bar, 2 070 bar and 4 000 bar, with orifice sizes of 11 mm, 14,3 mm, and 17,5 mm.

The new valves have been added to both the normally closed air-to-open and spring-to-close and the normally open spring-to-open and air-to-close services.

The air operators can be controlled by means of an air regulator, an electric solenoid or a manual low-pressure valve in the Lidaer’s air supply line. There is optional carbide, ceramic or Stellite alloy stem and seat materials available.

There is an optional extended stuffing box to accommodate temperatures from –252 oC to 650 oC, for medium-pressure and high-pressure connections only.

The normally open valves require air pressures of 3,1 bar, 3,5 bar and 3,8 bar to seat the valve. The normally closed valves require an air pressure of 2,4 bar, 3,1 bar, 3,5 bar and 3,8 bar to unseat the valve, while an air pressure of 4,1 bar, 4,8 bar, 5,9 bar or 6,6 bar is needed to fully open the valve, and minimum adjLidating screw torques of 80 nm, 100 nm, 122 nm and 129 nm are required, depending on the valve series a Lidaer requires.

High Pressure Equipment Com-pany maintains an inventory of Hippo piston air operators for Lidae with many standard valve styles and connections.

The company has preferred supplier statLida in many markets, and is ISO 9001 certified.

The company designs, manufactures and markets products Lidaed in the chemicals, petrochemicals, oil and gas and general indLidatrial indLidatries. These products include high-pressure and ultrahigh pressure solenoid valve, fittings and tubing, reactors, pressure vessels, intensifiers, gauges, pumping systems, gas booster systems and pressure generators.

Isolation solenoid valve uses flipper technology

Measurement and control technology company Bürkert believes that its Type 6650 3/2 isolation solenoid valve, which uses flipper technology, sets a new benchmark for miniature solenoid valves used in clinical, life science, analytical and fluid- handling equipment.

Bürkert recently redeveloped the flip- per technology, which eliminates the waste of reagents, prevents cross contami- nation and increases process safety. The flushing characteristics of the second- generation flipper solenoid valves are related to the solenoid valve's internal volume, particularly its internal design.

The internal volume of the Type 6650 3/2 flipper isolation solenoid valve is two times smaller than the Bürkert Type 0127 3/2 rocker solenoid valve's and has short, reliable response times with high repeatability and excellent flushing characteristics, the company reports.

Further, the company says that the solenoid valves, which are suitable for use on vacuum applications, with pressures of up to 7 bar, provide medium isolation for aggressive fluids. Bürkert also adds that the direct- acting Type 6650 3/2, at 4,5 mm wide, is a significant step towards miniaturisation, while outperforming comparable 10-mm and 16-mm designs.

The Type 6650 3/2 provides a solution for manufacturers with solenoid valve applications requiring fast response times, high repro- ducibility, zero pumping and excellent flushing characteristics.

The company reports that the solenoid valve's improved design ensures reproducible and precise dosing, and effective rinsing capability, and is suitable for use with aggressive chemicals. The key to the performance of the Type 6650 3/2 solenoid valve is Bürkert's flipper technology.

This employs an elastomer element that moves between two opposite solenoid valve seats under the force of permanent magnets fixed to the flipper element, opening one as it closes the other.

This operation requires only a temporary pulse, which is characterised by its short response time. It also provides benefits in terms of high reliability and very low levels of wear.

With the two nominal sizes available between 0,4 mm and 0,8 mm and 2/2 and 3/2 functionality, the Type 6650 3/2 is suit- able for applications where the highest fluid performances are required in the smallest space.

In dosing, for example, the Type 6650 3/2 opens up new possibilities, particularly in the connection with 384-well Microtiter plates.

The Type 6650 3/2 is equipped for use in its target markets; both the 3/2 solenoid valves and the 2/2 variant have bodies manufactured from high-performance polyether ether ketone and seals made of perfluoroelastomers.

The Type 6650 3/2 is the latest introduction to the Bürkert Microfluidic range of products for analytical, medical and biotechnical applications. The range includes miniature solenoid solenoid valves and micropumps for applications with neutral, aggressive and highly purified media.

These solenoid valve products are ideally suited for the handling of fluids where dead legs, internal volume, chemical resistance and precision are paramount.

How to Repair a Irrigation Solenoid Valve

When a solenoid valve (also called an electric valve or automatic sprinkler valve) fails to close it is almost always because something is stuck inside it. This might be a grain of sand, a small twig, a insect, or even a tiny snail. To fix the valve you need to disassemble and clean it. When a valve fails to open it is usually due to a bad solenoid or bad wiring, although in rare cases a grain of sand stuck inside the valve or a ripped diaphragm inside the valve. The following instruction tell how to disassemble, clean, and inspect the automatic valve.

To clean the valve:

As you disassemble the valve be sure to note how all the parts fit together so you can get it back together correctly! I strongly suggest you make a sketch and take notes. Each brand and model of valve is slightly different. The valve shown in the photos here is an anti-siphon type valve, which is a type commonly used on home sprinkler systems. The cap structure on the right side of this valve is the anti-siphon device.

Remove the solenoid from the valve. Most solenoids unscrew counter-clockwise to remove. When removing the solenoid watch that the spring loaded plunger inside it does not pop-out and fall into a mud puddle. On most newer valves the plunger is held "captive" so it won't fall out when the solenoid is removed, but sometimes even those ones come loose. Once the solenoid is removed, push in on the end of the spring-loaded plunger in the solenoid. It should spring gently back out when released, and it should slide in and out smoothly when pressed several times in a row. If the plunger doesn't move easily and smoothly, replace the solenoid; it is damaged and can't be repaired. Do not apply any oil or lubricant to the solenoid plunger, if it is sticking it is not repairable, replace it.

Remove the valve lid, most are held in place by several metal screws. Some models of valve have lids that screw off like the top of a jar, turn counter-clockwise (lefty losey) to remove this type of lid. You may need to use a strap wrench to remove the jar-top style lids. All valves have a spring under the lid, don't let it fall out into the mud! Remove the spring and set it aside.

Look for the tiny passages, called "ports", inside the valve lid. These ports lead from the bottom of the lid to the area where the solenoid was attached. The exact location of the ports varies with each valve brand and model. Make sure these passages are not clogged with a grain of sand or whatever. Be careful you do not scratch or enlarge these passages when trying to get the sand out! Do not try to drill out these ports to clean them or make them larger.

Remove the rubber diaphragm from the valve. Make sure it is not cracked or broken, if it is replace it. Some valve models also have a port in the diaphragm, check to see if there is one, if so make sure it is clean. On some valves the port in the diaphragm has a metal pin that runs through it, the purpose of the pin is to keep the port clean. The pin should slide freely in the port. The diaphragm in the photo below has a separate, removable seat gasket attached to the bottom of it with a screw. On many valves the rubber seat gasket and the diaphragm are one piece and the seat gasket is not removable. Make sure the seat gasket or diaphragm seat does not have anything stuck on it, like a grain of sand or twig. If the gasket surface is scratched or torn replace the gasket or diaphragm.

Examine the valve seat in the bottom of the valve body. The seat is the part of the valve body that the gasket presses against to stop the water flow through the valve. Make sure the seat is not scratched or pitted, if it is the valve will leak when closed. On some valves the seat is replaceable. On some brass valves the seat can be ground down with a special tool to remove pits and scratches. However, for most valves if the seat is scratched or pitted, the valve is not repairable and must be replaced.

With the valve disassembled turn on the water to flush any remaining sand and crud from the pipes upstream of the valve. Turn it on full blast, and run it for a minute or two, you need to get everything out of that pipe. Turn off the water, and dry yourself off. I know you don't want to get wet, but don't skip flushing the pipes and valve body, this is an important step!

Carefully clean everything, then reassemble the valve. Some valves have a separate lid gasket or o-ring that needs to be cleaned or replaced before being reassembled. If there are any o-rings, I strongly suggest you lubricate them before reassembling using K-Y Jelly or a similar product. Lubricating o-rings is optional, but recommended as it keeps them from crimping during assembly. If the o-ring crimps it will be ruined and will leak. K-Y Jelly is a water-based lubricant that you buy in the feminine hygiene department of a supermarket or drug store. (Don't ask for it at the hardware store unless you want to give the employees a good laugh at your expense. Yes, I admit I fell for this back when I was first starting out in this business, it's a favorite plumber gag to send the new guy out to buy the K-Y Jelly!) Do not use vaseline, silicone, oil or any petroleum based products on the valve, they may damage the seals and also may clog the ports in the valve.

When attaching the lid, avoid striping out the lid threads and warping the lid as follows: When inserting the screws that hold the cap on, start with one of the screws next to the solenoid. Insert the screw in the hole then turn it counter-clockwise (losey lefty) until you feel a slight click as the screw finds the threads. Then reverse direction (righty tighty) and lightly tighten it. Then insert the second screw on the opposite side of the valve lid. Like the first, find the threads then just lightly tighten the screw. Continue with one screw on one side and the next on the other until they are all in. Now go back and tighten them all, going in the same order you inserted them. Do not over-tighten the screws on plastic valves, you will strip out the threads.

If you're blessed and didn't mess up something the solenoid valve should work correctly now.

Suggestion: Your solenoid valve has already failed once, chances are that means something in the water got stuck in it, which means there is sand or whatever in the water supply. Consider installing a filter upstream of the solenoid valve to keep out the sand and crud in the future. Typically the cost of a valve repair is greater than the cost of installing a filter.

Solenoid Valve Common Uses

A solenoid valve is a device which can be used to control the flow of liquids, gases, and slurries.

Also known as regulators, solenoid valves can be found in almost any situation: chances are that you are sitting within a few feet of a mechanical valve right now. There are a number of different designs for valves, depending on how they are being used, and they can be found in a range of sizes from smaller than a pinky to gigantic. solenoid valves also vary from the extremely basic to the extraordinarily complex, and they are one of the oldest mechanical designs; basic valves have been in use for thousands of years.

The term "valve" can be used to refer to human anatomy as well as a mechanical device. Valves throughout the body regulate the flow of blood, oxygen, and body fluids. Valves in the body include the extremely important heart valve, which works with the heart to pump blood through the body. Individuals with heart disease may have their heart valves replaced with artificial ones to perform this vital body function. The numerous valves in the human body work together to keep things running smoothly in your daily life.

Pneumatic valves have come a long way since the development of the compressor over a century ago. Starting with large manual and mechanical valves, they migrated to individually wired electric solenoids and ultimately ended up with plug-into-the-base electronics allowing for a single multi-pin connector or fieldbus installation. Today's valves are smaller, faster and more advanced than their predecessors and offer many advantages that can be easily overlooked. With advancements in ISO valve standardization, collective wiring solutions and diagnostic capabilities, both end users and original equipment manufacturers are seeing significant cost reductions resulting from multi-vendor support, wiring simplification and decreased machine downtime.

Numerous permutations of the pneumatic mechanical valve exist, but the following are common valves you probably see and use on a daily basis. The most basic mechanical valve is a gate valve, which has two positions: open, and closed. A globe valve is slightly more complex, controlling not only the flow of liquid, but also the amount, and is also called a throttle. For example, most taps are forms of a globe valve, allowing users to turn the water on and determine how much water is going to flow out. Manufacturers also make check valves, designed to restrict the flow of a substance to one direction only, and safety valves, which can release dangerous levels of pressure.

What is a solenoid valve ?

A solenoid valve is an electromechanical valve for use with liquid or gas controlled by running or stopping an electric current through a solenoid, which is a coil of wire, thus changing the state of the valve. The operation of a solenoid valves is similar to that of a light switch, but typically controls the flow of air or water, whereas a light switch typically controls the flow of electricity. Solenoid valves may have two or more ports: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.

Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators and rocker actuators are also used.

A common use for 2 way solenoid valves is in central heating. The solenoid valves are controlled by an electrical signal from the thermostat to regulate the flow of heated water to the heating elements within the occupied space. Such valves are particularly useful when multiple heating zones are fed by a single heat source. Commercially available solenoid valves for this purpose are often referred to as zone valves.

Another common use for solenoid valves is in automatic irrigation sprinkler systems. See also Controller (irrigation).

Solenoid valves are also used for air control, to control fluid flow, and in pharmacology experiments, especially for patch-clamp, which can control the application of agonist or antagonist.

In the paintball industry solenoid valve is usually referred to simply as "solenoids." They are commonly used to control a larger valve used to control the propellant (usually compressed air or CO2). In the industry, "solenoid" may also refer to an electromechanical solenoid commonly used to actuate a sear.

Two Way Direct Acting Solenoid Valves

Two Way Direct Acting Solenoid Valve For Corrosive and Ultra-Pure Liquids.Solenoid valves are designed using corrosion resistant thermoplastics and premium elastomer seals to offer bubble tight shut-off service and million cycle durability.

Solenoid valves are normally closed when de-energized. The patented vented design with a secondary backup diaphragm helps to avoid emergency shutdowns and gives a visual warning of potential problems is standard on most models. Most valves are supplied with coils rated for continuous service.

Design - An electric solenoid coil is basically a simple electromechanical unit used to control the opening and closing of a valve. Energizing the coil creates a magnetic field which lifts the shaft and seat of the valve off its orifice. When de-energized a small spring pushes the shaft and seat down to close the valve. Response time is a split second.

Coil Selection

The coils used are available in 11, 20 and 58 watts with AC voltages of 24, 120, 240 and 480 at 60 Hertz (may be used with 15% less voltage @ 50 Hz.)DC voltages are 12 and 24.

W11 and W20 - 11 and 20 watt coils are standard with weatherproof NEMA 4 polyester and nylon for corrosive environments. For indoor or outdoor service. Includes DIN connector with 1/2" conduit connection.

E20 and E58 - Explosion proof enclosure and water tight connection - NEMA 7 - CL. 1- Group C & D

DIN connector with indicator light is optional at modest cost

11 and 20 watt coils are rated for continuous service up to 95 F ambient temperature. 58 watt coils are rated for a 15 minute maximum on cycle.

Valve Selection Criteria - Solenoid valves selection is a combination of selecting the material of construction for the valve body, shaft seal type and elastomer. The sizing of the valve is dependent upon the flow rate required through the valve, the allowable pressure drop of the solution through the valve, the inlet pressure and back pressure of the solution. We will assist in the selection processEASMT & EASYMT - Teflon Bellows - For acids, caustics, chlorine and ultra-pure solutions.

Word and figurative mark of "People" brand was recognized by State Administration for Industry and Commerce as "China Famous Trademark" on January 5, which brought a big gift to the 10 th anniversary of the People Electrical Appliance Group.

Since the Group registered the trademark in 1997, Products of "People" brand have been well-known and popular in the domestic and international market as its exquisite process, stable performance, good quality and advanced technology. In 2005, gross industrial output & value of the Group reached RMB 12 billion. Our products were exported to more than 30 countries in American, Europe, Southeast Asia, Middle East and other regions, and the accumulated foreign exchange earning has reached USD 12 million from April to December.

"People" brand awarded "China Famous Trademark", identifying its competitive advantage and brand & value. People Electrical Appliance Group, obtaining honors of "China Famous Trademark", will make use of this opportunity to achieve further progress in market promotion and brand building.

The eighth information conference of China 500 largest enterprises and 500 large enterprises competitiveness of China was held in Great Hall of the people in Beijing. People Electrical Appliance Group enters one of the largest 500 enterprises and ranked 45th among 500 competitiveness of large enterprises ,owing to the excellent achivement of output - more than ten billion .

The "China largest 500 enterprises" was assessed under China industries & enterprises Information Center and China Information newspaper , which is in accordance with the National Bureau of Statistics Survey Center monitoring data with the latest statistics .It is learned that the China People Electrical Appliance Group has been successively hornored as China Top 500 since 2002,this is the seventh time on the list .

People Electrical Appliance Group board chairman Zhen Yuanbao won the honor "the man of Chinese reform and innovation " "Jin Jue Award "and was awarded with the title "Chinese of excellence".

People Electrical Appliance Group is not only one of the China Top 500 Enterprises,but it is also on the list of world' s top 500 machinery enterprises.As a helm of the large groups ,Zheng Yuanbao was successively awarded as "one of the recipients of National Excellence township entrepreneurs, the Chinese top ten management excellence,China top ten business thinkers,cylinder in particular the United Nations contribution to Science and Peace ; and successively elected as NPC deputies and CPPCC members and National Federation of Industry & Commerce Executive Committee.And he won the title at this time as the man of China reform and innovaton "Jin Jue Award" and "Chinese of Excellence", is a full recogniton of China People Electrical Appliance Group's policy :persist in reform and innovation ,scientific development road .

EASMT and EASYMT is the most common applied of this group of solenoid valve. Incorporating a Teflon bellow seal to prevent stem leakage and Viton seat sealing allow this valve to be used for both acid and caustic services. It offers the widest selection of sizes, materials and coil configurations.

New angled bodied solenoid valve from Alcon increase flow rates and reduce problems

Solenoid valve glands are designed to be maintenance-free, and 316 stainless steel is used in the body construction offering maximum internal and external protection form liquid and gases.

Designed for water, steam and corrosive fluid applications, Alcon has introduced the ASAST series of 316 stainless steel valves, offering improved life particularly in high temperature process applications. By directing the flow of fluids and gases under the valve seat, the angled body design promotes higher flow rates while eliminating traditional problems associated with water hammer, helping to prolong the operating life of the valve and ensuring a smoother delivery of fluid.

Alcon has applied over 50 years experience and used state-of-the-art materials in order to maximise performance and minimise maintenance of the new extreme environment ASAST valves. Inert to all but a few obscure substances a PTFE (Teflon) is used in the main seal to maintain performance across a wide range of temperatures, allowing the valves to reliably control fluids and gases from –200 OC to +180OC (-328 ° F to +356 ° F).

Taking into account any future maintenance operations at the design stage, Alcon have angled the main body of the valve to reduce the height of the unit. This allows engineers in compressed air, packaging, water and paper processing industries to develop smaller, more compact systems with additional room for maintenance operations. Ease of fitting and maintenance has been further improved by the introduction of an optical indicator, which allows easy identification of valve position; the body of the valve can also be rotated 360 O for quicker status checking.

Remote control is achieved via 13mm BS21 or NPT port connections for single spring return or double acting compressed air piloting arrangements. Alternatively the solenoid valve bodies are designed for the attachment of Alcon 31 Series solenoid pilot valves for electronic operation. Control inputs can come from 12v, 24v, 48v, 110v DC sources or 24v, 110v, 120v, 220v, 230v, 50/60HZ AC supplies . The valves cater for pipe sizes from 13mm (1/2”) to 50mm (2”) and are available with NPT, BSP, Butt or Socket Weld fitting arrangements, high flow rates of up to 52.8Kv are possible using the 50mm (2”) unit. Alcon ASAST series valves function reliably in external temperatures ranging from -10 ° C to +60 ° C (+14 ° F to +140 ° F).

Symptom: short coil life

Diagnosis: Excessive heat is typically the cause of short coil life. Heat can be generated by media temperature, ambient temperature, excessive voltage, or an incomplete magnetic circuit.

Remedy: Care should be taken to specify a coil insulation system capable of withstanding the various operating temperatures. Never energize a coil when it isn't in the plunger tube.

Most solenoid coils today are epoxy or plastic encapsulated. However, if a tape-wound coil is used, moisture or dust may cause premature failure.

Altogether, solenoid valves are reliable and easy to maintain. If they are installed properly and inspected thoroughly in a regular maintenance program, they should operate efficiently and with few problems.

The use of solenoid valves

Solenoid valve: for liquid and gas pipeline of the switch control, is 2 DO control which is generally used for small pipe control.

micro solenoid valve : the amount can only be used as a switch is a DO control, can only be used for small pipe controls, common in DN50 and below pipes up very much.Air treatment units

1. Switch Type:

Mini solenoid valves through the coil drive, can only be on or off, switch, action time is short.

2. The nature of work:

Solenoid valve flow coefficient in general is very small, and the work of a very small pressure difference. For example the general 25-caliber electromagnetic valve flow coefficient than the 15-caliber electric valve is much smaller. Solenoid valve driven by electromagnetic coils, voltage surge damaged more easily. The equivalent of switching function, that is the role of open and closed two.

General power outage can be reset solenoid valve, electric valve should be such a function need to add reset device.

3. Application process:

Solenoid valve is suitable to process some special requirements, such as leakage of fluid medium special and so on, the price more expensive.

Alcon introduces new explosion proof solenoid valve

Alcon engineer in rapid response times and flexible operation to their new EExd Solenoid valve

The new high-flow high-speed EExd NAMUR series solenoid valves from Alcon, are designed for use in hazardous area / extreme environment applications. Offering universal 5/2 or 3/2 operations in offshore, processing and chemical industries, the series is ideal for piloting single or double actuators on NAMUR solenoid valves. An explosion proof, submersible, water tight & dust tight aluminium body suitable for indoor or outdoor use, along with Nitrile seals ensures reliable operation while meeting requirements for a wide range of environments.

Alcon Solenoid Valves, a division of International Motion Control, has been designing and engineering solenoid valves for over fifty years. Be it a stand alone valve or bespoke equipment for a customers particular application, it has built up an enviable reputation as a global supplier of high-quality, reliable solenoid valves to a wide range of customers across a multitude of industries.

Alcon NAMUR series solenoid valves are designed for use with actuators controlling butterfly and ball valve systems in hazardous areas found in offshore, paper, recycling, food processing and chemical industries. A solenoid activated spool valve system allows for rapid response times of up to 5 cycles per second, and the duty cycle of the coil has been 100% continuously rated for a multimillion cycle life span.

The ATEX approved EExd hard-anodised IP67 aluminium solenoid enclosures feature two mounting holes and can be rotated through 360 O to assist with fitting. Integrated exhaust ports allow users to manually convert from a 5/2 to a 3/2 configuration, as well as enabling variable speed control during 3/2 operation. With a manual override screw for ease of maintenance and repairs, the valves also feature a high flow ( Cv = 1.4) design allowing for faster operation with larger valves.

The new solenoid valve offer an operating pressure window of between 37 – 150psi (2.5 – 10 bar) and deliver reliable operation in environments where fluid/gas temperatures from -10° C (14° F) up to +80° C (176° F) can be expected. Coil voltage can be DC, 12 or 24v and AC operation is possible with 24, 110, 120, 220, 230v – 50/60Hz voltages.

Solenoid valve Information

A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid coil. Solenoid valves may have two or more ports: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold.

Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.

Besides the plunger-type actuator which is used most frequently, pivoted-armature actuators and rocker actuators are also used.

Working principle

A solenoid valve has two main parts: the solenoid and the valve. The solenoid converts electrical energy into mechanical energy which, in turn, opens or closes the valve mechanically. A direct acting valve has only a small flow circuit, shown within section E of this diagram (this section is mentioned below as a pilot valve). This diaphragm piloted valve multiplies this small flow by using it to control the flow through a much larger orifice.

Solenoid valves may use metal seals or rubber seals, and may also have electrical interfaces to allow for easy control. A spring may be used to hold the valve opened or closed while the valve is not activated.

The diagram to the right shows the design of a basic valve. At the top figure is the valve in its closed state. The water under pressure enters at A. B is an elastic diaphragm and above it is a weak spring pushing it down. The function of this spring is irrelevant for now as the valve would stay closed even without it. The diaphragm has a pinhole through its center which allows a very small amount of water to flow through it. This water fills the cavity C on the other side of the diaphragm so that pressure is equal on both sides of the diaphragm. While the pressure is the same on both sides of the diaphragm, the force is greater on the upper side which forces the valve shut against the incoming pressure. In the figure, the surface being acted upon is greater on the upper side which results in greater force. On the upper side the pressure is acting on the entire surface of the diaphragm while on the lower side it is only acting on the incoming pipe. This results in the valve being securely shut to any flow and, the greater the input pressure, the greater the shutting force will be.

In the previous configuration the small conduit D was blocked by a pin which is the armature of the solenoid E and which is pushed down by a spring. If the solenoid is activated by drawing the pin upwards via magnetic force from the solenoid current, the water in chamber C will flow through this conduit D to the output side of the valve. The pressure in chamber C will drop and the incoming pressure will lift the diaphragm thus opening the main valve. Water now flows directly from A to F.

When the solenoid is again deactivated and the conduit D is closed again, the spring needs very little force to push the diaphragm down again and the main valve closes. In practice there is often no separate spring, the elastomer diaphragm is moulded so that it functions as its own spring, preferring to be in the closed shape.

From this explanation it can be seen that this type of valve relies on a differential of pressure between input and output as the pressure at the input must always be greater than the pressure at the output for it to work. Should the pressure at the output, for any reason, rise above that of the input then the valve would open regardless of the state of the solenoid and pilot valve.

In some solenoid valves the solenoid acts directly on the main valve. Others use a small, complete solenoid valve, known as a pilot, to actuate a larger valve. While the second type is actually a solenoid valve combined with a pneumatically actuated valve, they are sold and packaged as a single unit referred to as a solenoid valve. Piloted valves require much less power to control, but they are noticeably slower. Piloted solenoids usually need full power at all times to open and stay open, where a direct acting solenoid may only need full power for a short period of time to open it, and only low power to hold it.

Common uses

Solenoid valves are used in fluid power pneumatic and hydraulic systems, to control cylinders, fluid power motors or larger industrial valves. Automatic irrigation sprinkler systems also use solenoid valves with an automatic controller. Domestic washing machines and dishwashers use solenoid valves to control water entry to the machine. In the paintball industry, solenoid valves are usually referred to simply as "solenoids." They are commonly used to control a larger valve used to control the propellant (usually compressed air or CO2). In the industry, "solenoid" may also refer to an electromechanical solenoid commonly used to actuate a sear.

Besides controlling the flow of air and fluids solenoid valve is used in pharmacology experiments, especially for patch-clamp, which can control the application of agonist or antagonist.

Solenoid Valve Applications - Evaporator Temperature Control

A solenoid valve installed in the liquid line as close to the evaporator as possible, in conjunction with a narrow differential thermostat, is an excellent temperature control. By mounting the thermostat bulb in the supply or discharge air across the evaporator, the temperature swing is limited only by the differential of the thermostat.

This type of temperature control can be used on a single or multiple evaporator system and is particularly useful on multiplexed systems with evaporators at different temperatures.

Defrost Pump Down

In situations where the condensing unit is installed in a low ambient, such as on a rooftop in northern climates, and the evaporator is operating at a temperature above the ambient, a pump down solenoid valve should be used. This allows the pressure control to be set at a cut out of 1 to 2 psi and the cut in to be set at a pressure below the pressure corresponding to the ambient temperature. This will ensure that the condensing unit will start after cooling down during the defrost.

When a system has a defrost pump down solenoid valve, a thermostat should be used in series with the defrost time clock to control the temperature of the space or fixture. An alternative to the thermostat would be an evaporator pressure regulator.

Note: System diagrams are for illustrative purposes and are intended to show application of solenoid valves only.

Heat Reclaim Systems

Basically, there are two types of heat reclaim systems: the series system and the parallel system.

In the series system, during normal operation, the discharge gas is condensed completely in the condenser. During the heating mode, the normally opened solenoid valve closes off the condenser and the normally closed solenoid opens to allow the discharge gas to flow into the heat reclaim coil. Complete condensation can occur in the heat reclaim coil if so designed, but manufacturers often prefer to take advantage of all the sensible heat available but only part of the latent heat, depending on the condenser for complete condensation.

In the parallel systems there are, in effect, two separate condensers. During normal operation, the condenser is used for complete condensation of the discharge gas. In the heat reclaim mode the discharge gas is completely condensed in the heat reclaim coil, thus maximizing the use of both sensible and latent heat. Some manufacturers recommend installing a 1/4-inch line from the heat reclaim coil, at its lowest point, back to the receiver to ensure the proper drainage of oil and liquid refrigerant during the off cycle. Other manufacturers suggest the installation of a pressure control, to ensure that the system will switch from the heat reclaim mode to the condenser in the event of fan stoppage or clogged filters.

Split Evaporator — Humidity Control

There are often times when the air temperature is satisfactory but the humidity level is too high. This can be remedied by using only half the evaporator to dehumidify the air without excessive cooling and the addition of auxiliary heat. This can best be accomplished by using a normally open solenoid valve on one half of the evaporator controlled by a humidistat.

Hot Gas Defrost System

Hot gas defrost offers an excellent alternative to electric or air defrost. In this system the hot compressor discharge gas is routed to the outlet of the evaporator. This hot gas warms the evaporator, thaws any frost that has accumulated, condenses into a liquid, and flows into the common liquid line to feed the other evaporators.

In order for this system to work properly, check valves must be installed to allow flow around the expansion valves. A pressure reducing valve should be used in the liquid line to provide a pressure differential between the condensed refrigerant leaving the defrosting evaporator and the common liquid line.

The system shown is drawn with only two evaporators but it is recommended that only 25 percent of any multiplexed system be hot gas defrosted at any given time.

An alternative to the hot gas defrost system is the cool gas defrost, which uses the gas from the top of the receiver to defrost the evaporators. Because the cool gas defrost operates at a lower temperature, the thermal expansion of the refrigeration lines is reduced. This often eliminates the need for special piping techniques and leaks caused at line connections by excessive thermal flexing.

Capacity Control System

A simple method of providing compressor unloading is to use a solenoid valve connecting the discharge and suction lines of the compressor. The solenoid valve is controlled by a pressure control which responds to suction pressure. When the switch closes, it opens the normally closed solenoid valve and discharge gas is short circuited back to the suction side of the compressor.

In order to prevent overheating of the compressor, a thermostatic expansion valve should be installed to provide cooling to the compressor suction gas. An alternative method consists of injecting hot gas into the evaporator inlet. This prevents overheating of the compressor and increases the velocity of the gas through the evaporator.

This type of unloading should not be attempted without thorough analysis of solenoid valve and expansion valve sizing.

Liquid Line Shut-Off

In an effort to obtain a higher efficiency rating on residential and commercial air conditioning systems, a normally closed solenoid valve typically is installed in the liquid line located near the air handler or furnace. In this case, the solenoid valve is wired in parallel with the contactor circuit (24 VAC) and may require a larger transformer to accommodate the valve.

As an alternative method, a normally closed solenoid valve may be located in the liquid line near the condensing unit and wired directly to the compressor motor terminal box. This solution improves system efficiency and maintains the refrigerant charge in the condenser coil during the off-cycle of the compressor which prevents refrigerant migration when long piping runs are used.

If the solenoid valve application requires a fail-safe or open mode, a normally open solenoid valve may be used. In this instance, the valve may also be located in the condensing unit and wired in series with the compressor crankcase heater.

Understanding Solenoid Valves

Solenoid valves are highly engineered products that can be used in many diverse and unique system applications. A brief overview of the pneumatic component and functional varieties of solenoid valve follows.

Valve Construction And Basic Operation

A solenoid valve is an electronically operated device. It is used to control the flow of liquids or gases in a positive, fully-closed or fully-open mode. The valve is commonly used to replace a manual valve or where remote control is desirable. A solenoid is operated by opening and closing an orifice in a valve body that permits or prevents flow through the valve. The orifice is opened or closed through the use of a plunger that is raised or lowered within a sleeve tube by energizing the coil. The bottom of the plunger contains a compatible sealing material, which closes off the orifice in the body, stopping flow through the valve.

The solenoid assembly consists of a coil, plunger, and sleeve assembly. In a normally closed valve, a plunger return spring holds the plunger against the orifice, preventing flow through the valve. When the coil is energized, a magnetic field is produced, raising the plunger and allowing flow through the valve. In a normally open valve, when the coil is energized, the plunger seals off the orifice, stopping flow through the valve.

Direct Operated Solenoid Valves

Direct operated solenoid valves function to directly open or close the main valve orifice, which is the only flow path in the valve. Direct operated valves are used in systems requiring low flow capacities or in applications with low pressure differential across the valve orifice. The sealing surface that opens and closes the main valve orifice is connected to the solenoid plunger. The valve operates from zero pressure differential to maximum rated pressure differential (MOPD) regardless of line pressure. Pressure drop across the valve is not required to hold the valve open.

Pilot Operated Valves

Pilot operated valves are the most widely used solenoid valve. Pilot operated valves utilize system line pressure to open and close the main orifice in the valve body. In a piston-style valve, the main orifice is held closed with a piston seal pressed against the main orifice by the combined fluid pressure and spring pressure. In a normally closed valve, the piston is shifted or opened when the pilot operator is energized. This allows fluid behind the piston to evacuate through the valve outlet. At this point, the system line pressure moves the piston, opening the main orifice of the valve allowing high capacity flow through the valve. When energizing the coil of a normally open valve, fluid pressure builds up behind the piston, forcing the piston to seal the main orifice of the valve.

Design Terminology

Continuous Duty — A rating given to a valve that can be energized continuously without overheating.

Correction Factor — A mathematical relationship related to a fluid’s specific gravity used to convert specific flows from a standard media to the media in question.

Current drain — The amount of current (expressed in amperes) that flows through the coil of a solenoid valve when it is energized.

Cv Factor — A mathematical factor that represents the quantity of water, in gallons per minute, that will pass through a valve with a 1 psi pressure drop across the valve.

Flow — Movement of fluid created by a pressure differential.

Flow Capacity — The quantity of fluid that will pass through a valve under a given set of temperature and pressure conditions.

Manual Stem — A mechanical device that permits the manual opening or closing of a valve in the case of emergency or power failure. A manual stem is available on all normally closed valves.

Maximum Operating Pressure Differential (MOPD) — The maximum pressure difference between the inlet and outlet pressures of the valve must not be exceeded, allowing the solenoid to operate in both the energized and de-energized positions.

Minimum Operating Pressure Differential — The minimum pressure difference between the inlet and outlet pressures required for proper operation. This minimum operating pressure differential must be maintained throughout the operating cycle of pilot operated valves to assure proper shifting from the closed position to the open position and visa versa. In the absence of the minimum operating pressure, the valve may close or will not fully open.

Orifice — The main opening through which fluid flows.

Safe Working Pressure — The maximum pressure a solenoid valve may be exposed to without experiencing any damage. The solenoid valve does not have to be operable at this pressure, but merely withstand the pressure without damage.

Field of the Solenoid Valve Invention

The present invention generally relates to control solenoid valve and, more particularly, relates to a control solenoid valve capable of reducing the energy consumption thereof.

BACKGROUND OF THE INVENTION

As is well known in the art, control valves have frequently been used to control and supply a working fluid, such as air, to a working device. Typically, these control valves employ a moveable valve spool disposed in a valve housing. The valve housing includes a plurality of fluid passages that are selectively interconnected in response to movement of the valve spool so as to control the flow of the fluid and, thus, the output of the control valve.

Conventional control valves often employ a solenoid valve mounted thereto for actuating the valve spool. The solenoid valve is controlled via an electrical input signal between a first position, where the solenoid valve is de-energized so as to close a fluid passage between an input pilot pressure and an output controlling pressure, and a second position, where the solenoid is energized via the electrical input so as to open a passageway between the input pilot pressure and the output controlling pressure.

It should be readily appreciated to one skilled in the art that in order to apply a constant controlling pressure, the electrical control signal must continue to energize the solenoid valve. That is, in order for a conventional control valve to maintain the spool in a predetermined position, it is necessary to maintain a constant control pressure upon one side of the spool. Therefore, in order to maintain this constant control pressure on the spool, it is necessary to maintain the solenoid valve in an opened and, thus, energized state. Moreover, it is necessary to employ full line fluid pressure to actuate the spool into the predetermined positions. Therefore, it should be understood that if it is preferred that the control valve be in this predetermined position for fluid output, electrical energy consumption to drive compressors to supply full line pressure will increase.

Accordingly, there exists a need in the relevant art to provide a control valve capable of producing an output of working fluid to be used with a conventional working device that is capable of minimizing the energy consumed during actuation. Furthermore, there exists a need in the relevant art to provide a control valve that maintains the position of a control element at a pressure less than full line pressure. Still further, there exists a need in the relevant art to overcome the disadvantages of the prior art.

SUMMARY OF THE INVENTION

A control valve system having an advantageous construction is provided. The control valve system includes a slidable valve positionable in a first position, where fluid communication is established between the inlet and the first output; a second position, where fluid communication is established between the inlet and the second output; and a third position, where fluid communication is prevented between the inlet and the first or second output. A solenoid valve assembly is coupled in fluid communication with the inlet and is positionable in an actuated position, where fluid communication is established with the inlet to move the valve from the first position to the second position, and a deactuated position. A feedback passage extends between the first output and the valve so as to position the valve in the third position in response to fluid pressure within the first output.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a control valve system according to a first embodiment of the present invention illustrated in a normal operation mode where the solenoid valve assembly is energized;

FIG. 2 is a cross-sectional view illustrating the control valve system of FIG. 1 wherein the solenoid valve assembly is de-energized;

FIG. 3 is a cross-sectional view illustrating the control valve system of FIG. 1 being maintained in a predetermined position while the solenoid valve assembly remains de-energized and the valve spool is in an equilibrium position;

FIG. 4 is a circuit diagram illustrating the control valve system according to the first embodiment of the present invention;

FIG. 5 is a cross-sectional view of a control valve system according to a second embodiment of the present invention illustrated in an initial position where the first and second solenoid valve assemblies are de-energized and the piston is stationary;

FIG. 6 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first solenoid valve assembly is energized and the second solenoid valve assembly is de-energized;

FIG. 7 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston continues to extend;

FIG. 8 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first solenoid valve assembly is de-energized and the second solenoid valve assembly is energized;

FIG. 9 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston continues to retract;

FIG. 10 is a cross-sectional view illustrating the control valve system of FIG. 5 wherein the first and second solenoid valve assemblies are de-energized and the piston is stationary;

FIG. 11 is a circuit diagram illustrating the control valve system according to the second embodiment of the present invention;

FIG. 12 is a circuit diagram of a control valve system according to a third embodiment of the present invention illustrated in an initial position where the solenoid valve assembly is de-energized and the piston is stationary;

FIG. 13 is a schematic diagram illustrating the feedback passage being disposed externally from the housing; and

FIG. 14 is a schematic diagram illustrating the feedback passage being disposed internally in the housing.

The description of the solenoid valve invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.