Solenoid Valve Applications (Full)

Solenoid valves in air compressors

The way the solenoid valve will work in the compressor is as follows:

When the system is operating, the electric motor runs the compressor, which takes in filtered air, compresses it, sends it to the refrigerator and finally to the tank. 
During this stage, the solenoid valve is energized and closes the circuit keeping it under pressure. 




When the tank reaches the requested pressure reading, a pressure switch stops the motor and the check valve keeps the air inside the tank. 
To prevent the compressor from remaining under pressure for too long and so getting damaged, the solenoid valve is then de-energized and it allows exceeding air still in the circuit to be exhausted.  

There are three variants of solenoid valves that would be used in this application, the RD236, the RB214 and the RB203.

The RD236 and RB214 are direct acting solenoid valves whilst the RB203 is a pilot operated solenoid valve.




Here is a PDF file with a bit more detail about solenoid valves in this application: 
Solenoid Valves In Air Compressors


Solenoid valves in metering valves

The system operates as follows: first corn is ground and flour is stocked into the silos. The flour is then taken from the silos to be put into a tank and mixed with water. The mixture thus obtained is distributed to the network by a pump. 

The MV intercepts the feedstuff and regulates its distribution to the manger thanks to the elastic diaphragm. The diaphragm is operated by the pressure of air let into the upper chamber of the solenoid valve. 

As a matter of fact, when the solenoid valve (assembled on the cover of the MV) is de-energised, air flows from P to B, pressing the diaphragm and closing the MV; when it is energised air from the chamber is exhausted from B to R and the MV opens





The variant of solenoid valve that would be used in this applications is:




Here is a PDF file with a bit more detail about solenoid valves in this application: 


Solenoid valves in press safety valves

Two 3-way solenoid valves are used in this application. 

When they are de-energized (Picture 1), they close the inlet of pressurized air from P (red) and connect outlet A to the exhausts R. 
The value of pressure inside the pipes is controlled by pressure gauges CP. 
The two solenoid valves are operated at the same time by an electronic panel (Picture 2). 

The solenoid valves close their own exhausts allowing air to flow through the pipes to the piston chambers, which are pushed downwards by pressure. At this time air can flow from P to A. 

If a failure was simulated, for example by de-energizing only the valve on the right, the piston on the left would be pushed upwards by the spring because of a lack of pressure and would open the exhaust. 

Air (yellow) from P would flow towards R thus blocking the valve, which would operate again only when the system was safe. The valve would reset automatically when the stand-by position was restored. 


The variant of solenoid valve that would be used in this application is:


Here is a PDF file with a bit more detail about solenoid valves in this application: 


Solenoid valves in vibrating feeders

A circular vibrator consists of a vibrating base, a container and a separate electronic controller for setting the excursion of the vibration.
Containers can be of various shapes: cylindrical, conical, or stepped; they have a spiral guider in the internal wall that allows small parts to ascend to the linear feeder. A magnet operates a pulsating force on the container and the vibrations thus produced move the small parts forwards along a track inside the container. 

A series of traps at the end of the track select parts in a wrong position and let them fall at the centre of the container so that only properly positioned parts are ejected. A solenoid valve intercepts compressed air from the system and shoots it against the small parts to push them into the assembly machine. 
A photocell is positioned at the mouth of the feeder. 

When the container is empty, the system detects a failure, the vibrator stops, a warning light turns on and the de-energized solenoid valve interrupts the blast of air. Only the intervention of an operator can reset the process. 
The most frequent failures are due to not properly positioned parts getting stuck or the container is empty.



The type of solenoid valve that would be used in this application is:



Solenoid valves used in dentist chairs




Integrated station with all the necessary dental or ophthalmic equipment, complete with automatic chair and adjustable lamp. All automatic functions are easily run by the operator through a console. 

The chair lifting system works under the thrust of a hydraulic cylinder operated by the medium (oil). Compared to a mechanical system, the hydraulic thrust has the advantage of a “smoother” movement.




Two solenoid valves are used in this application to regulate the height of the chair. 

Oil is taken from the basin by the pump and let into the circuit at a pressure of 12-13 bar. When a button is pressed on the console, the solenoid valve is operated: it intercepts oil in the pump and sends it to the cylinder. 
The cylinder enables hydraulic energy to be turned into mechanical energy thus lifting the chair to the desired height. 

By pushing another button, the second valve opens. Under the effect of the overhanging weight, oil under pressure inside the cylinder is exhausted into the basin, and the chair is pushed down.



The type of solenoid valve that would be used in this application would be:



A special version of valve D263 is recommended for this application. Unlike the standard valve, it is equipped with a cone-shaped spring on the plunger, with a heavier load. 
With this option, fixed core and plunger do not stick due to the viscosity of the medium when the valve closes (i.e. when the coil is de-energized). 

The plunger is equipped with a Ruby seal to guarantee very high performances.


Solenoid valves in automatic hot drinks dispenser

Hot drinks dispensers are made to distribute coffee, tea and other hot drinks quickly and are usually placed in public areas, work offices or private facilities.



Vending machines for espresso or lyophilised coffee and soluble hot beverages. The main feature of vending machines consists in a quick distribution of coffee, tea, milk and chocolate in working places, public or private facilities (offices, factories, hospitals, schools, bars, restaurants, etc.). 

Vending machines usually consist of two supplying groups, one for coffee and one for soluble beverages. This sheet describes the operation of the group for soluble beverages, and specifically the use of vending valves with media at atmospheric pressure.



The sequence of distribution is the following: first the plastic glass is positioned, then sugar is supplied and finally, the beverage and the coffee spoon are delivered. 
When the user selects the product on an electronic push-button panel, the infusion process is activated. 
A volumetric dispenser prepares a single-dose of powder into the mixer. 

Hot water at a temperature of 90-95°C is delivered from the boiler to the mixer by a vending valve. The level of water inside the boiler is kept constant by an electronic system letting in fresh water from the water supply whenever it is necessary. 

Finally, the mixer exploits the centrifugal force to dissolve the powder in water and so obtain the beverage. After the mixing operation, the mixer stops and the beverage is delivered into the glass by gravity. 

The types of solenoid valves used in hot drinks dispensers are:





Solenoid valves in coffee-in-cartridge dispensers

Coffee-in-cartridge dispensers are used to provide coffee and other hot beverages from cartridges, these are usually semi-automatic.


Semi-automatic coffee-in-cartridge dispensers complete with hot water delivery heads are used to supply coffee and soluble beverages in a cartridge. 
The hydraulically moved coffee infusion unit automatically expels the cartridge into the specially provided container. 

The dispenser can be equipped with a support cabinet with cup dispenser, spoon and sugar drawer and product storage compartment with door. Small dimensions and easiness of use make them widely used as household appliances but also in shops, offices, associations, laboratories, hotels and wherever a constant supply is not required. 


Water contained in a tank is sucked up by a vibrating pump and then intercepted by two three-way solenoid valves. 
The former supplies the hydraulic actuator, the latter delivers water to the boiler. The boiler is always full of hot water whose temperature is adjusted by a thermostat. It is installed on the actuator stem and is equipped with a feeler pin nozzle that delivers hot water when it is pressed. 

The operation starts when the cartridge is in; the two solenoid valves open at the same time and the actuator pushes the boiler downwards against the cartridge. 
A safety valve above the second solenoid valve prevents water from flowing out before the actuator has descended completely. 

When the pressure of 9-10 bar has been reached inside the circuit (about 10 sec.), the safety valve opens, cold water flows into the boiler while water that had previously been warmed up flows out and filters through the cartridge. 

The mixture produced (coffee, tea, chocolate, cappuccino, etc.) flows through a nozzle into the cup. 
At the end of the cycle, the second solenoid valve closes and exhausts the remaining hot water under over-pressure from the third way into the collecting tank. Then the first solenoid valve closes and water under pressure inside the actuator is exhausted from the third way into the tank. 

The actuator returns into its rest position under the effect of the spring. When a different control is selected, only hot water is delivered: a two-way solenoid valve connected directly to the boiler intercepts hot water and pours it directly into the cup through a different nozzle.

The types of solenoid valves typically used in this application are:



Solenoid valves used in industrial ironing boards

Integrated industrial ironing boards for the final finishing of clothing. The appliance is equipped with iron, vacuum blow table and sleeve form board. 
Ironing boards, utility presses and spotting tables make up an ironing group for various operators. Each machine can be self-contained or connected to a steam, vacuum and compressed air set. 




The system exploits steam to ease the ironing of clothing. 
The iron is equipped with a push-button control that supplies steam on the cloth when pressed. 

The solenoid valve installed on the ironing board controls the steam produced by an electric boiler and sends it to the iron when the push button control is operated. 
The solenoid valve is fitted with a flow regulator (screw or knob) that enables the operator to regulate quantity and pressure of steam to be applied on the garment being ironed.


There are three solenoid valve variants that would be used in this application:


A solenoid valve capable to withstand many cycles every day is needed for this application. 

The three types we recommend are all compatible with the requested application but have different features. 
Valve D260 has a very large orifice (6 mm) but the maximum pressure is 5 bar - 150° C. Valve D267 has an orifice of 3 mm or lower but can reach 180° C -10 bar; the standard seal is Rulon and the coil is class H, therefore it is suitable for exacting industrial applications.  


Solenoid valves in car washing systems

Self-service car washing systems are an innovation in the car washing field; they are self-service washing areas for cleaning vehicles like scooters, motorcycles, camper vans, caravans, small boats and all-terrain vehicles that cannot be cleaned in traditional car washing systems with brushes. 

The system delivers high-pressure water mixed with wax, detergent and car washing foam through a lance and a brush.



The user selects a cleaning cycle on the control panel and cleans the vehicle using two basic tools: a lance and a brush. 
While the vehicle is being rubbed, the brush pours liquid detergent to remove dirt. During the shampooing cycle, two solenoid valves let cold and hot water into the circuit. 

Three more solenoid valves inside the circuit intercept liquid detergent, foam and wax respectively and mix them with water. 
An electromechanical pump sucks up the mixture by depression and lets it back into the circuit at 80 bar. Before reaching the brush, the liquid is further mixed with air. 

The lance is a washing gun shooting either water or shampoo under pressure, according to the selected cleaning cycle. 
Usually, water used for rinsing is softened and osmotic, a treatment that prevents white limescale from staining the vehicle. 



The solenoid valve used in this application is:


The recommended valve is solid. In this application, it carries out various functions. The body is Nickel coated so as to protect brass against corrosion when detergents flow through it. 


Solenoid valves used in dryers

In their typical application, air dryers are used to remove the condensate in compressed air installations. 

Compressed air produced by compressors contains a large quantity of steam that can condensate and provoke important damages in the equipment utilizing it. 

In the most common applications about 70% of water is eliminated by the final cooler, whereas for the remaining 30% only an air dryer is effective. 
The diagram below shows a typical installation of an air dryer in an industrial system for air treatment: (1) Air Compressor; (2) Cooler;(3) Separator; (4) Tank; (5) By-pass Valve; (6) Dryer. 



Inside an air-to-air exchanger, compressed air going into the system is precooled by dried compressed air coming from an evaporator; then it enters the evaporator where it is cooled down to Dew Point by the evaporating frigorific medium (freon). 

The condensate produced during the cooling process is set apart and drained; before leaving the system, compressed air is heated in the air-to-air exchanger mentioned above. 

The refrigerating circuit produces cold needed to cool compressed air to Dew Point (2°C-3°C). Cold produced by the refrigerating system adjusts to the temperature and flow rate changes of compressed air thanks to a by-pass valve with “hot gas”. 

The valve prevents the temperature in the evaporator from going down and consequently the condensate from freezing. 
The level of condensate in the tank is controlled by a level sensor connected to the control panel. 

The control panel operates a solenoid valve so that only the condensate produced is drained. 
So are useless and expensive losses of compressed air avoided. A warning light notifies problems in the exhaust system.




The solenoid valve used in this application is:



The recommended valve combines small dimensions and performances suitable for use with compressed air (0-15 Bar). 
Since this is a direct acting valve with a rather small orifice (2,2 mm) it should be fitted with a filter to prevent condensate from clogging the valve. 

Important: The use of a timer operated solenoid valve competes with a more refined and much more expensive system based on a zero loss timed electronic drain with no waste of compressed air.


Solenoid valves in electronic mixers


Equipment for supplying water without hand contact. By moving the hands in the infrared area of taps or approaching shower and urinal systems, water will flow. 
The use of electronic mixers is compulsory in places requiring special precautions, such as hospitals and public places. 

Furthermore, this application will get a reduction of consumptions due to the fact that the water supply stops automatically a few seconds after use.


The system is based on an optical sensor (photocell) producing an infrared beam of light. 

When the beam is interrupted by the presence of a body the sensor sends an electric impulse to the control unit, which electrically operates the two solenoid valves. 

The valves are connected to the hydraulic system and deliver hot and cold water. Thanks to a mixer, the water temperature is properly regulated.




The solenoid valve used in this application is:



A remarkable flow rate is needed for this application. 
Therefore the choice of a pilot operated solenoid valve in place of a direct acting valve is justified by a very large nominal diameter (13 mm). 

In addition, the recommended valve undergoes a Niploy coating process to withstand outdoor deterioration caused by the atmosphere in places like urinals. 


Solenoid valves in floor washing machines

Household appliance for automatically cleaning floors, suitable for industrial use. The cleaning system consists of a rotating brush rubbing the floor. 
The appliance is equipped with a tank containing water and detergent, which are released on the brush when the operator presses a button.



The solenoid valve allows water and detergent to flow from the tank to the rotating brush. The valve max working pressure is close to zero because fluids contained in the tank are at atmospheric pressure.
 The solenoid valve is electrically operated by a button on the machine console.




The solenoid valves used in this application are:



Water is not under pressure, therefore, a 2/2 way direct acting vending valve is suitable for this application. 

The valves proposed above have a simple construction and a very large nominal diameter, (11mm) for the brass construction and (13 mm) for the plastic construction. Since the valve can be exposed to strokes while being used, a brass body is to be preferred. 

The brass body is the female GAS connection, whereas the polysulphone body has a hose tail connection (inlet 17.5 mm fitted with 3/8”, outlet 16.5 mm). 

While developing the project it is important to make sure that the valve is not exposed to stresses. Some customers like the 45° inclination of the outlet of the plastic body, which eliminates an angle. 
In addition, the plastic version has an exhaust hose tail used in applications with beverages, which needs to be capped in this application.

Solenoid valves in foam makers 


Foam markers are used to bound the ground to be processed by farm machines. They are fit to weeding machines, manure spreaders and sewing machines to prevent some areas from overlapping or not being treated. 

The system mixes a foaming agent with air, thus generating bubbles of white foam that fall to the ground at regular intervals marking areas that have already been processed.




The compressor sends compressed air to the tank containing the foaming agent, which passes to the dispenser under the effect of pressure. 

A battery of solenoid valves (two for the foaming agent and two for air) located on the dispenser is operated by an electrical control and allows medium and air under pressure to pass through their pipes. 
Foam bubbles are generated at the end of the process when air mixed with the foaming agent is ejected through the nozzles.




the types of solenoid valves used in this application are:



The three valves proposed are all suitable for this application. The best compromise, however, is type 248 because: 
- of its smaller overall dimensions and greater solidity as compared to type B297 
- the power of series 8 coils is between series 2 and series 7


Solenoid valves in hydro saunas

Space designed for body treatment. 

It combines all the functions of the bath and shower areas in a single structure: hydromassage, hydroshower, lymph drainage, plantar massage and steam sauna can be set by a control panel. 

The panel is installed inside the cabin and allows the user to choose among various combinations of functions, adjusting also temperature and time. 

Besides being equipped with accessories like stereo radio, telephone and clock, multifunction showers possess safety and hygiene systems like automatic disinfection and drain system.




The solenoid valve connected to the exhaust carries out the automatic function of the drain system: at the end of each program, the control panel operates the solenoid valve, which lets out the water inside the bath. 

The outflow is followed by an automatic cleaning that removes any stagnation or deposits of water in the system, thus preventing limestone from forming.




The type of solenoid valve used in this application is:


The solenoid valve recommended for this application is a vending valve because the exhaust is not under pressure.


Solenoid valves used in a kit for sewing machines

Equipment used for weed killing. It is fit to sowing machines led by farm tractors and distributes liquids on the ground during the sowing process.




The liquid from the tank is certrifugated by the electropump and sprayed on the ground by a blade spreader positioned at the back of the machine, with a 120° inclination. 

The solenoid valves and the electropump are operated by an electronic control in three different stages. In the first stage, the electropump is operated. 
The solenoid valves letting the liquid into the spinning electropump (starting working stage) are then operated. 

The third stage anticipates the closing of the first solenoid valve and allows the electropump to drain the liquid remaining at the end of the process.




The solenoid valve used in this application is:



This application requires a steady delivery of liquid under pressure (5 bar). If a pilot operated solenoid valve was used in this application, the weedkilling liquids would clog the nozzle of the diaphragm. 

Therefore a 2-way direct acting solenoid valve is recommended. The type suggested above has a 4 mm main orifice (the largest orifice that can be used to satisfy the requested performances). 
The Viton seal is suitable for controlling weedkilling liquids (pesticides, herbicides, fungicides, insecticides). 
The supply of the farm tractor cab makes it necessary to use the valve with a 12V DC coil. 


Solenoid valves used in media perparators

Automatic equipment for preparing Agar, a sterile nutritive soil used to grow bacteria. 

Agar is used in microbiological analyses of drugs, cosmetics and food. Food contamination by pathogenic micro-organisms is one of the major problems faced by the food industry. Biochemical analyses detect contaminations in a short time. 

Samples of products to be analysed are filtered and distributed on Petri plates containing nutritive soil favouring the reproduction of bacteria. 

When the reproduction does not take place at the scheduled times, the product can be marketed.



The media preparator carries out various operations: mixing, warming, sterilizing, cooling, are done in a single container, where thermolabile substances are also added. 

Two solenoid valves are used in the sterilization circuit, operated by a head control panel. With the first solenoid valve, cold water is taken from the water system and let into the system. 

When Agar has been dosed on the plates for growing bacteria, water that has warmed up during treatment is exhausted through the second solenoid valve.




The type of solenoid valve used in this application is:



The type of solenoid valve recommended for this application is quite robust and has a 5.5 mm main orifice. 

This large orifice ensures an extremely high flow rate with a performance of 3.5 bar, more than enough to manage the pressure of water from the water system, usually delivered between 2 and 3 bar. 


Solenoid valves used in thermoconvector ovens - steam

A professionally mixed oven is a triple oven combining forced convection and steam cooking. 

Steam is generated instantly in the pre-cooking chamber; uniformity of cooking is favoured by the forced ventilation and the slight overpressure obtained in the airtight chamber. 
In the combined mode the quality of cooking is improved by the automatic control of the quantity of steam let into the chamber. 

The control panel guarantees precise working temperatures and allows to check the temperature of the product by a core drill



The steam circuit includes a steam generator overheating water taken from the supply system. 

Water is then let into the cooking chamber in the form of steam. The function of the solenoid valve is to exhaust the tank collecting the condensation. 
When the oven is on, the solenoid valve is energized by the electronic panel and closes the exhaust hermetically. 

At the end of the cooking cycle the oven is turned off and the solenoid valve de-energized. It opens the exhaust from the tank so that condensate accumulated during cooking is drained off.




The types of solenoid valves used in this application are:



For this application, we recommend a normally open direct acting solenoid valve because it works only when the oven is on. 

Since the solenoid valve remains energized most of the day, a robust model and a class H coil are requested. The latter is designed to better resist heat generated by the electric power. 

The flow rate is unimportant because the maximum capacity of the collecting tank is 1 litre and the pressure is close to zero.


Solenoid valves in thermoelectric heaters 

Thermoelectric heaters combine the principles of fireplaces, boilers and heaters. 

As a matter of fact, they are a heating source for the whole house through the radiators placed in the various rooms and produce hot water for sanitary fixtures like modern boilers. In addition, they can barbecue, bake, grill and roast at the same time.




The system exploits heat generated by the combustion of wood or gas to warm water and distribute it to the various household fixtures. 

Two solenoid valves are connected to the hydraulic system of sanitary water. With the former cold water is taken from the water supply and let into the circuit of the thermoelectric heater. 

Water flowing close to the smoke exhaust warms up and is controlled by the second solenoid valve to be distributed to the sanitary fixtures (bathrooms, kitchen) in the house.




The type of solenoid valve used in this application is:



A remarkable flow rate is needed for this application and therefore the choice of a pilot operated solenoid valve rather than a direct acting solenoid valve is justified by the very large passage. 

The recommended valve is a standard type for use with water with an NBR seal. 


Solenoid valves used in water meters

Water meters are electromechanical appliances allowing the supply of a predefined quantity of water to an equipment placed below. 

Applications are various; the most important is in the food industry. In ovens for baking bread or pasta, water meters are used to supply the exact quantity of water when the dough is kneaded. 

Water meters are equipped with analogue or digital readers.




The water meter has the function to measure the quantity of a liquid flowing through it. 

A predefined rating is set by using a knot: when it is reached, the water meter sends an electric signal to the solenoid valve placed below, which closes, thus stopping the supply of the liquid.




The type of solenoid valve used in this application is:




Solenoid valves for this application are usually pilot operated, in order to have a larger flow rate. 

When water is not taken from the water system but from a tank, the pressure is very low and therefore it is necessary to make use of pilot operated solenoid valves with assisted lift, which work with a minimum working pressure equal to zero.


Solenoid valves in exposure units

Exposure units are machines designed for the printing and silk-screening fields and used for exposing pre-sensitised aluminium plates.
The machine works on images imprinted on films and reproduced on the plate.

An operator mans this machine by laying the plate on the carpet and, after closing the glass-holding frame, pushes the start button on the control panel. 

The exposure unit is equipped with a microprocessor to carry out the complete working schedule automatically: preheating of the lamp, pre-vacuum, vacuum, selection of the lamp power, main and secondary exposure, masking, switch-off of the lamp, re-establishment of the pressure. 

The solenoid valve and the vacuum pump are responsible for the cycle of creating a vacuum inside the unit. When the pump is on the normally open solenoid valve is energized and closes the circuit keeping vacuum inside the unit. 
At the end of the exposure, the pump stops and the solenoid valve is de-energized, opening the circuit to the outside and thus restoring the atmospheric pressure inside the unit. 



The type of solenoid valve that would be used in this application:



Here is a PDF file with a bit more detail about solenoid valves in this application:
Solenoid Valves in Exposure Units


Solenoid valves in vacuum packers

Another Vacuum application that our solenoid valves have been used in is a packer.
A Vacuum packer is used to vacuum pack food in a different environment. This would be useful for supermarkets or butchers. 
Food is vacuum packed to prolong its preservation.


Foodstuffs inside plastic bags are blocked by the transparent bell. The bell is lowered and the vacuum cycle starts when a button is pressed. 
The air inside the chamber is sucked up by the pump as indicated by arrows (fig.1); vacuum is generated and the plastic bag sticks to the product; an edge of the bag is then sealed. 

When this operation is over, the atmospheric pressure in the packing chamber is restored (fig.2) and the bell is opened. 

Two solenoid valves are employed in this application for the vacuum cycle. The former allows the pump to suck up air from the chamber and keep the vacuum in the room when the sucking up operation is over. 
The latter restores the atmospheric pressure after the packaging has been sealed.

The type of solenoid valve that would be used in this application is:



Here is a PDF file with a bit more detail about solenoid valves in this application:
Solenoid Valves in Packers


Solenoid valves in refrigerant loading systems

A refrigerant loading system is used to replace refrigerant gas in refrigeration systems. 
The unit will carry out a vacuum cycle followed by a loading cycle; it automatically checks vacuum signalling even for small leaks in the system, then quickly loads the refrigerant without the risk of a mistake.


The system is designed for three NC solenoid valves: (1) for loading the refrigerant, (2) on the vacuum line, (3) in the intake line of the vacuum pump (vacuum test). In the vacuum cycle solenoid valves, 2 & 3 open and the pump takes in remnant gases from the air conditioner and lets them into a disposal container. 

Once the vacuum cycle is over, solenoid valves 2 & 3 close, the pump stops and the solenoid valve 1 opens. Now the loading cycle begins and the refrigerant flows from the cylinder into the circuit of the air conditioner under the effect of vacuum. 

Thanks to the electronic scales the system will load the exact quantity of gas that had been previously taken.

The type of solenoid valve that would be used in this application is:


Here is a PDF file with a bit more detail about solenoid valves in this application:


Solenoid valves in vacuum pumps

Vacuum pumps are devices that convey a defined volume of air from the suction to the exhaust areas, creating depression.


Electromechanical vacuum pumps usually operate on continuous duty and the requested level of vacuum is controlled by two solenoid valves positioned on the side of the vacuum. 

For example, in manufacturing semiconductors this system allows to stop the suction of air from the working chamber and divert it to a secondary way, thus keeping the requested vacuum conditions inside the chamber. 

In applications like this where the production of printed circuits requires a controlled atmosphere, an inert gas is used. 
The gas enters the chamber per decompression. Therefore the system herewith described performs a safety function as well, preventing the gas from leaking outside. 

The types of solenoid valves that would be used in this application are:



Here is a PDF file with a bit more detail about solenoid valves in this application:

Solenoid Valves in Vacuum Pumps


Process Solenoid valves

Solenoid valves are simple and effective electrically operated valves to control liquid, gas or steam.  Solenoid valves have many uses, from controlling compressed air to operate pneumatic equipment, controlling high-pressure oil to operate hydraulic equipment.  
A solenoid valve that controls the actual media would generally be considered a process valve.
A solenoid valve can be used in a wide range of environments to control a multitude of media.The important consideration is that the correct solenoid valve must be selected.
Ambient temperatures can range from sub-zero conditions such as in a refrigeration unit to desert-like conditions. We must consider the pressure parameters, the media temperature ranges, the frequency of operation, they may even be used in a highly explosive environment like a flour mill or an environment containing combustible gasses. Selecting the right valve for the application requires a great level of skill and experience.

In order to select the correct solenoid valve for an application, we would need to collect all the technical data, such as the media, the pressure, the differential pressure, the temperature, the voltage available, the environment, the frequency of operation. 
All of these factors would affect which solenoid valve is selected.

The basic principals of a solenoid valve.
The principal of a solenoid valve uses a copper wound coil over an armature housing a fixed core and a moving core. When the coil is electrically energised the moving core is attracted to the fixed core. 



When a coil is energised, the armature is attracted to the fixed core, the spring is compressed and the valve is opened allowing flow. Lifting the armature to the fixed core consumes more power than holding the armature, this is referred to as the inrush and holding power. The inrush is the power required to lift the armature and the holding is the power required to hold the armature in place. 

The armature is made of a specific grade of stainless steel,1.4105 EN (AISI 430F). This grade of steel is magnetic and also suitably erosion resistant. 

A solenoid valve should be selected if any of the following conditions are met:
  • There is a media without dirt particles.
  • The flow volumes are at a moderate rate.
  • There is an average differential pressure.
  • The operation is running at a high speed.
  • The media's viscosity is not higher than 21 cST (3°E).
V-Flow supply three variations of process solenoid valves:
  • A direct acting solenoid valve
  • A pilot operated solenoid valve
  • A pilot operated solenoid valve with assisted lift
*(NC = Normally closed, NO = Normally open)
**(2/2 way = valve has two connections, only two positions open or closed. 3/2 way = valve has three connections and 2 passage flows.)

A direct acting solenoid valve
*(NC or NO)
**(2/2 or 3/2 way)

A direct acting solenoid valve uses a coil and armature centred on the valve. The seal is mechanically connected to the armature. The seal can be produced from a wide range of materials and selected depending on application, this means that the seal can be manufactured to withstand certain pressures, temperatures or chemical attributes. The armature is made of stainless steel grade 1.4105 EN 10088 (AISI 430F). There is a spring which holds the armature in its de-energised state.
The valve can be either NC and NO. An NC variant means the valves original position is closed, the armature is sealing the valve. When the coil is electrically energised, overcoming the force of the spring, the valve is opened. When the armature, and seal, are lifted away from the orifice, the media will begin to flow through the valve. The armature will be held in position by the magnetic force. 
When the coil is de-energised, the armature is released from the fixed core and will return to its original position. When the armature re-seats, the seal will close the valve.
The direct acting solenoid valve does not require differential pressure to function as it is operated purely by the coil power.

A direct acting solenoid valve has an average response time of 5÷25 ms.

Another variation of this valve would be a 3/2-way direct acting solenoid valve. This functions in a very similar way to the 2/2 valve. One variation implements an exhaust through the fixed core. There is a seal on both the top and bottom of the plunger, this will allow flow to or from the body seat or exhaust seat depending on the configuration. 

Pilot operated solenoid valve
*(NC or NO)
*(2/2 way)

A pilot operated solenoid valve is similar in operation to a direct acting solenoid valve, however the pilot operated solenoid valve is acting upon a pilot orifice rather than the main orifice.  The solenoid here has no direct impact upon the main orifice, rather than lifting and replacing the seal, like with a direct acting solenoid, a pilot operated will seal a pilot orifice to keep the inlet pressure from escaping into the outlet.
This type of solenoid valve requires a differential pressure from inlet to outlet. This is because the diaphragm is sealed with the inlet pressure. There is a spring acting on the main diaphragm however the pressure from the inlet will be the main factor in keeping the valve sealed. When the coil is energised the armature is again pulled to the fixed core, releasing the seal from the valve. The pressure which was trapped above the diaphragm will now be able to escape through the pilot orifice and into the outlet. As the pressure comes into the outlet it will push upwards against the main seal and this will cause the valve to open, allowing flow.
When the coil is de-energised, the pilot orifice will become sealed again, this will stop the pressure flowing through and will trap it above the main diaphragm once again. When this happens, the seal will be pushed back onto the seat, closing the valve.
The reason this valve can work is because of the differential pressure from the inlet and outlet. Without this differential pressure, the valve would not be able to function. This means, for example, that a pilot operated solenoid valve would not be able to work in a boiler system where the pressure is consistent throughout the entire system. This valve would be suitable for operations in mains water. Mains water is pressurised between 4-6 BAR, it also does not contain any particles. This valve offers excellent flow rates for this application.
As mentioned before the pilot operated solenoid valve requires a differential pressure range to function. The minimum amount of pressure must be between 0.3 and 1 BAR, depending on the size of the valve. The orifice of the valve is small and so any particles in the media could damage or disrupt the operation of the valve. So only media without any particles can run through this valve.
Pilot operated solenoid valves are available in both NC and NO configurations. This enables the valve to be used in a multitude of different applications providing the specifications and environment is correct.

This valve has an average response time of 50÷500 ms.




Pilot operated solenoid valve with assisted lift
*(NC)
**(2/2 Way)


A pilot operated solenoid valve with assisted lift is a combination of both the direct acting solenoid valve and the pilot operated solenoid valve.
The pilot operated solenoid valve with assisted lift has the armature, which is mechanically connected to the diaphragm, and coil centred on the valve. When the media is running at low pressure the valve will be operated by the coil, raising the diaphragm by energising the coil and lifting the armature to the fixed core. When the pressure flowing through the valve is at an optimal rate, the pressure will assist in lifting the diaphragm.
This means that the valve will only be capable of full flow at high pressures.
Pilot operated solenoid valves with assisted lift can operate with no pressure differential, because of the use of the solenoid on the main diaphragm, however, they are not available in a normally open configuration.
A typical application of a pilot operated solenoid valve with assisted lift would be within a diesel fuel supply. Generally, diesel fuel is supplied from a header tank, meaning that the fuel may not be at a sufficient pressure to operate a standard pilot operated valve. This is where an assisted lift pilot operated solenoid valve should be used. It is recommended that Viton seals should be used for this application.

This valve could also be used in a low-pressure water system, or a system where pressures fluctuate and may drop to zero. Or a system where back pressure can increase resulting in a very low-pressure differential across the valve. As mentioned before this valve does not require a pressure differential to operate.

The average response time of this valve is 50÷500 ms.  

Optional features that can be added to V-Flow Solutions solenoid valves:


Manual override:
Normally closed direct acting and pilot operated solenoid valves can be supplied with a manual override which allows the valves to be opened independent of electrical current.

How this works:
A small CAM will be built into the valve, below the armature. When the CAM is rotated, it lifts the armature, opening the valve.

Waterhammer control:
Pilot operated solenoid valves can be supplied with a system that has the ability to regulate the closing speed of the diaphragm in order to control waterhammer.

(Waterhammer is caused by an increase in flow pressure through a previously empty valve).

The anti waterhammer device is a needle valve incorporated into the valve body. By rotating the needle valve clockwise the needle valve restricts the orifice reducing the flow rate, thus slowing the closing speed of the diaphragm.

Benefits of V-Flow Solutions solenoid valves:


Robust construction for industrial applications Featuring stainless steel orifice on most models.
High reliability
Long life
Stainless steel operators with low residual magnetism according to:
1.4105 EN 10088 (AISI 430F)
Corrosion resistant
High performance
High-quality seal materials
NBR, FKM, EPDM, PTFE, Sigodur (Filled PTFE), Ruby, Kalrez.
High compatibility with a wide range of media
Fully interchangeable coils with a wide range of AC and DC voltages.
High flexibility with reduced stock
Coil orientation possible through 360°
Simple and quick installation
Coils tested 100% in compliance with the current EC directives.
Compliance with RoHS directive and to relevant international standards upon request.
Development and realisation of special projects
Customer tailored solutions

















----------------------------

Comments

Popular Posts