Solenoid valves for Hybrid fill system

Hello,

My first posting here at the rocketry forum and I am glad to have found yet another group of kindred rocket enthusiasts.

I need some 12v or 24v solenoid valves for an N2O filling system for hybrid motors. NOS sells some but they are quite expensive and are not continuous duty.

Does anyone know of a source (new or surplus) of good, relatively inexpensive solenoid valves, 1/4" NPT size?

Thanks! GDS

Hey GDS,
I've recently began looking for the exact same thing. Have you ever found out anything? I've found cheaper solenoid valves but, I don't know enough about what requirements need to be adhered to when used with N2O. However, from what I've read, any valve that can handle compressed CO2 can also handle N2O. Please keep me posted on whatever you find.

Mark,

Could you tell me where you found the info that CO2 rated valves could handle N2O? From my knowledge of chemistry CO2 would be an inert gas while N2O would be an oxidizer.

I'd therefore be worried about using CO2 valves in this application since solenoid valves usually have one or more O-rings used as seals. If the O-rings were made out of a combustable material, say synthetic rubber, wouldn't they either degrade, burn, or explode when exposed to pressurized liquid N2O?

Ken Holloway, NAR #78336, L-1

Well, I don't have the exact site handy right now. I'll have to get it next week when I get to work. However, I found the information on a British gentleman's site who creates his own N2O systems for racing purposes. He describes how you can create an N2O system using solenoid valves that are rated for CO2. He's been doing it for years. He did mention that he had to do something special about the seals though. Can't remember the exact details. Sorry. The real question is... Who knows what are the requirements for a solenoid valve to handle pressurized N2O?

Mark,

From 22 years experience working in Nuclear procurement I'd guess that the requirements would be as follows:

1. Body and all metal parts exposed to N20 to be made out of stainless steel.

2. All valve seals and seats (soft goods) made out of teflon.

3. Lubrication using Krylox(?) or other non-oxidizing lubricant.

4. Sealed operating coil and "leak free" design to prevent accidental explosions.

The only "high volume" use for such valves that I can think of would be in oxygen supply systems. Does anyone out there have experience in the design, production, or use of oxygen supply systems in hospitals?

Ken Holloway, NAR #78336, L-1

Well, my brother designs oxygen supply systems for military aircraft contracts. I'll ask him if he knows the answer and if so, if he knows of a good supplier of valves.

Mark,

I came across someone who works for NOS and might be able to get some of the NOS solenoid valves surplus. NOS makes N2O solenoid valves for nitrous racing systems so they are already qualified. Only problem is that they have a limited duty cycle. But there are "solenoid saver" circuits that are easy to make to reduce the current demand once the valve opens. A friend of mine has used these valves successfully with such a circuit in his hybrid fueling system. If I can get a lead on this surplus supply, I'll post the information for anyone interested in acquiring some.

Regards,
George

TRA 07725
(aka GDS)

Thanks, George. I appreciate it. I've been looking at the same solenoids from NOS. Best price I've found, however, is about $75. If I only knew what the specs were for those solenoids, I could shop around for comparable solenoids. I think it's obvious that we'll pay a premium price if we get these things from "speed shop" vendors. The surplus deal sounds good, though.