high speed, high pressure air valves 1

[morg]

Hello,

I need an electrically controlled valve or method to move 250 cubic inches of compressed air at 4000 psi in 10 milliseconds or less. Off to On to Off again. In 0.010 Seconds. Is it possible? Are there air valves of that speed? Alternate methods? Longevity - 10 million cycles. If this is not possible, where is the trade-off? speed, volume, or pressure? Thanks for any help.

Morg

 

[vpl]

You might take a look at the answers to this post:

thread408-246102

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[morg]

Thank you,

Yes, of course I had read that earlier post. I am putting together an engine for use in environments that cannot stand fuel combustion. I have plenty of compressed air to achieve the torque required. I just need to be able to inject the correct amount at the correct time. I also need the flexibility to change the time to fire and the duration.

Thanks

 

[israelkk]

Did you try to calculate the orifice needed? it is huge.
Is this a 250 cubic in vessel that you are trying to purge to the atmosphere? or a line that you want to open and close and pass to where? to the atmosphere? What is the downstream pressure?

 

[rconner]

While of course not claiming any relevance to your application, it is interesting that at least nitrogen (and whatever else with maybe some nasty smell!) can be generated quite quickly with some pressure at least in auto "air bags" e.g. as explained at

http://auto.howstuffworks.com/airbag1.htm

etc.

 

[morg]

OK
Here are the new specs. We are going from 4000 psi to 2000 psi on the output. I need 0.003 cubic Ft/30 mS. Time to open and close is 0.030 Seconds. Repeatable.

Anyone?

Thanks
Morg

 

[iainuts]

Hi morg. Doesn't sound like an off the shelf valve to me, primarily because of size and pressure. There are quite a few aerospace valve manufacturers that make similar valves though, and may already have something that can fit your application or perhaps be modified to do so. I'd suggest checking Thomasnet

http://www.thomasnet.com/products/aerospace-valves-95983086-1.html

I'd start with Marotta, Valcor, and ITT

http://www.marotta.com/

http://www.valcor.com/

http://www.ittaerospace.com/scripts/products/index.asp?p=valves

or just Google "aerospace solenoid valve"

http://www.google.com/search?hl=en&q=aerospace+solenoid+valves&aq=f&oq=&aqi=

 

[morg]

Thank you iainuts. I will.

Morg

 

[israelkk]

morg

It is a big change from your original post.
How many valves you need?
Has it to comply with a specific code (Commercial, Aerospace, Military?
How many life cycles?
Voltage supply value?
Maximum current available?
Internal and external leakage?
Valve maximum dimensions (Length, diameter)?
Where are you located?

 

[morg]

israelkk

I need approximately 16 immediately for testing, then more.
industrial use.
10 million if possible.
12 - 24VDC
50 A
dont know leakage, prefer none.
dimensions - 8" cube
Kentucky

Firing frequency in use 3 - 30 times per second

Morg

 

[israelkk]

I am a little confused with the 0.003 ft^3 per 0.03sec flow rate. Usually when the flow rate is given as a volumetric flow it means volume at standard atmospheric pressure and temperature (STP). If this is the case you are asking for very low flow rate of ~0.125 grams of air per sec. This means a miniature valve. If this is not the case you should specify a mass flow rate.

 

[morg]

OK Israelkk,

Mass flow is 0.005 lbs/Second. However, that mass flow is integrated over one second. The reality is 0.00015 lbs/0.03 Seconds per valve fire time. Or the valve fires 33.3 times per second for 0.03 seconds per fire. The total mass flow is the 0.005 lbs/second mentioned above.

Sorry for the confusion. I am not accustomed to this discipline.

Morg

 

[israelkk]

To my calculations the orifice diameter needed to allow the flow rate of 0.005 lb/sec from 4000 psi upstream pressure of 2000psi down stream pressure is approximately 0.06 to 0.1 mm. This is a very small diameter. For example, an existing commercial valve , that I designed and developed for a company in Israel, has a 0.3 mm dia. orifice. The valve working pressure is for upto 5000psi (20000 psi burst pressure for commercial use). The valve diameter is 40 mm and the length <100 mm.

This valve can be adapted to your need.

This valve was custom designed for a specific commercial machine which is sold all over the world, therefore, you need to take into account some NRE to change the orifice and design an adaptor to you system.

Please note that with such small orifice the supplied air may need to be very clean and probably dry (few ppms of water and hydrocarbons) to avoid freezing across the orifice when the air expands from 4000psi to 2000psi.

As I understand your compamy is based in Kentucky USA

http://israelkk.googlepages.com/home

 

[morg]

israelkk

What is off-on-off time of your valves? What is the largest orifice for that speed and pressure?

Morg

 

[israelkk]

With your current requirements for valve ON time of 30 msec this valve is much faster than that as far as I recall it is less than 10 msec. However, by easily changing the coil resistance (at the expense of higher current) and/or raising the supply voltage the ON time can be much shorter. The current orifice is 0.3 mm dia.

The valve is designed such that the pressure creates the sealing force. The current valve is working under 5000psi on one side and 14.7psi on the other side. In your case it is 4000psi and 2000psi. Therefore, the sealing force is smaller with your system. To keep the same leakage value (very very small - bubble tight), the orifice need to be smaller than 0.3 mm but much larger than what you need according to your previous posts.

One more remark, you mentioned "the valve fires 33.3 times per second for 0.03 seconds per fire" this means that the whole cycle is 33.3 msec therefor, it includes the ON time plus the OFF time. If we assume they are equal than the valve haS to open in ~16 msec.

Are you using PWM to control the flow?




There is no point getting into details because your exact requirements are not yet clear. For example, How exact the 0.005 lb/sec need to be? How will you operate the valve. How accurate the 4000 and 2000 psi are? and more. How much need to the OFF time of the valve and more?

If you decide to proceed with the manufacturing company they can adapt the coil, orifice, voltage, etc. to your need and probably to larger orifice and flow rates mentioned in your previous posts as long as it doesn't require major change to the valve.

They can custom design a whole new valve too but it will cost you more.

 

[morg]

Israelkk

If I can get one with an orifice .3mm right away, I'll take it. Tell me how.

Morg

 

[israelkk]

Use the end of the following link to send me an E-mail and I will give you the contact E-mail of the manufacturing company.

http://israelkk.googlepages.com/home