Nitrox stick solenoid

[Blue Abyss]

I am in the process of building a Nitrox stick for my little 2.5 cfm Bauer compressor.
A number of different sources recommend putting a solenoid valve on the O2 feed into the Nitrox stick. This does sound like a smart idea but I have yet to see anyone actually recommend what sort of valve would be best to use and how to wire it up.
Please give me some ideas what I should be looking for (also where to find one) and how it might be integrated in to the system.

BB

 

[oxyhacker]

Gas or electric?

The main reason for a solenoid is for use with electric motors without magnetic starters, since they can stop then restart by themselves during power interruptions, and may fill up with O2 in between with bad results when they restart. So if your compressor is gas, or has magnetic starter, a solenoid is not terribly necessary.

The problem is, O2 safe solenoid valves are hard to find, and you really don't want to use one not approved for O2 in a situation like this, since a number of possible failures could let the pressure rise once the valve closed, to the point where the pressure could build up high enough to have the potential for trouble.

One way around this is to use just any random solenoid, but a three-way, and locate it downstream of th orifice/needle valve, so it dumps the O2 when the power stops, rather than blocking flow. This way, it can never see more than slightly above ambient pressure, which greatly lessens the chance of bad things happening.

 

[flounderer]

Just in case you decide to go that route, here is an O2 clean solenoid valve we use in the aquaculture industry.

http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/8489/cid/2039

Pat