looking for high-speed, high-temp pwm solenoid valve

[bootup]

I am looking for a high-speed, normally closed 2-way or 3-way valve to control hot water injections. It would be ideal if I could control that valve with a 0-5V or 0-12V PWM signal. The water will be introducted to the valve at about 600F and 1500psi. The valve will cycle from 1Hz-80Hz and have a maxium open time of 0.5-5ms. Each cycle will emit 0.1-1cc of water.

Try as I might, Google (and every other resource I've found) has not led me to companies that carry valves in this temperature or speed range. The closest I've come is Clean Air Power's hydraulic valves. But they won't quite run hot enough or fast enough and they're not willing to do custom work.

 

[buzzp]

Not to discourage you, but I have never seen a valve with the operation times you need. Not to say they are not made. It will interesting to see if anyone knows where such an animal exists.

 

[ALEXFV]

bootup:
You are looking for an application that solenoide cant't handle. Let me explain you:
There's no coils (not commercial) that can deal with 600 °F, because of force of magnetic field depends on temperature (among other factors), and protection needed is more than nuclear spec.
Coil reaches its own temperature, and you have to added ambiente temperature. For a pressure rating like this, on DC, you will have to use a huuuge coil, that obviously will reach very high temperature.
On the other hand, open time for almost all brand is more that 30 msec. You haven't include diameter, so is difficult to provide you a good answer.

Besides, solenoid valves can be cicled by around 2-3 times per second as maximum due to heting, friction and time for magnetic induction.

As per buzzp: I haven't seen nothing like you are looking for.

It seems for me that you saw something like a fan cutting the flow. This is not an application for solenoid valves.

 

[bootup]

The Clean Air Power valve is close in speed (5ms open time) and a little further in temperature (300F). It seems with a slightly more robust solenoid and better insulation, it's within reach.

 

[ALEXFV]

Bootup:

You are right, but take care that you are talking about valves for FLUID POWER (pneumatic) application, not for FLUID CONTROL (W.O.G.S. for example) application...these are two quite different fields.

All people with experience on solenoid valves keeps in minds the two distinctions.

Seal's friction for temperaure so high as 600°F will demand a huuuuuuge coil. For these kind of parameters, you need to use grafoil seal as minimmum, and as large as I know, it doesn't exist solenoid valves with grafoil seals.
If you don't trust on this forum, please check catalogue of ASCO (

http://www,ascovalve.com)

for nuclear products...
There's a section of GET LITERATURE, and you can download basic principles of selection an engineering on coils for solenoid valves.

These are the most insulated valves in world, and they can't reach cycle neither pressure rating you are looking for.

Good hunting.

 

[bootup]

Thanks for the information. This is clearly not any area where I have any experience. I did not mean to imply that I did not trust this forum, only that I found at least one valve that was "close" on a couple of parameters.

The valve I'm looking for is not for fluid control. The water will be vented into a 14psi, 200F environment. ambient around the valve will be 70F with a cool air supply.

 

[israelkk]

To my best knowledge the only way is to mechanically separate the solenoid actuator from the sealing plunger so that the high temperature will not reach the coil. Adding cooling to the solenoid will be even more desireable. This however will increase the total mass that the actuator has to move to seal or open the vent orifice. I do not know if there are such valves on the shelf that can do the job but it seams to me that a custom one can be developed. Such valves are used for hot gas pneumatic actuators in the aerospace missiles but they are usually for short missions.

Without actually making a layout of the valve, calculating the sealing force flow rate and orifice diameter and solving the magnetic and mechanical dynamic behavior it is difficult to give a definitive answer.

It will much easier to meet the lower range specs in the original post because they will require very small orifice diameter but if the valve has to be able to meet the whole range then the larger values of flow will dictate the sealing orifice diameter and as a result the coil and plunger size and mass which will affect the open and close time.

Another issue is the sealing material, plastic such as vespel may work but it is on edge of their ability therefore, I think ceramic to ceramic or metal to metal seal or ceramic to metal seal may be needed.

Last, how tight the seal should be? is a small leak allowed?
I assume it is allowed especially at the high Hz frequency where there is no much meaning for sealing ability.

 

[tigertommy]

Please take a look at

http://www.circle-seal.com/atkomatic/index.html

You might something you could use in this site.

tbtn

 

[MikeHalloran]

It doesn't sound like a valve application to me at all. At first I was thinking of driving a gear pump with a motor, and controlling the motor speed with the PWM signal.

But because of the water pressure, easily sufficient to backdrive even a crappy pump, you don't need a motor, you need a brake and a tachometer.

I.e., balance the tachometer signal (pump rpm) against the PWM, and use the error to modulate the brake.



Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[Fzob]

A long time ago I remember seeing a valve in a similar application. They used what was basically a multi ported valve that rotated. It looked like a small drum. As each port passed the opening it would allow a small amount of water to pass. The interval depended on the rotational speed.

I can't remember where it saw it or who made the valve. Sorry