Valve jam with liquid gas

[wyz2285]

So I have been toying around the idea of using propane with solenoid valves and piston valves. However the valve jams every few shoots. The o-rings on the piston are free float and seals fine, but the piston opens very slowly, as if the o-rings are swollen.
Is it because of the cold? Any suggestion regarding the o-ring material?

[Boomerang]

Cooling things down shouldn't make orings expand, but if it gets cold enough, propane/moisture could certainly freeze on the surfaces.

Does it do the same thing if your propane canaster is vertical (top upwards) during the entire fueling process? Idea being to reduce feeding evaporating (and therefore freezing) liquids from the fill mechanics.

[Moonbogg]

Any chance of some pictures and a description of how it works?

[Anatine Duo]

propane doesn't behave with some rubbers; might be swelling the o-rings

When we switched from acetylene to propane at work we had some torch heads and regulators get fussy

[wyz2285]

So I started with a coaxial piston launcher with plans to use solenoid to trigger it. However if I fill it with propane in gas form (filling with bottle pointing upwards) it kinda makes a decent Bang. Then I filled it with the propane bottle upside down so the liquid can get in expecting more power, but the Bang was much smaller. I noticed the piston (with o-ring) gets a lot harder to move after use, I kinda have to lube it after every use.

[wyz2285]

So I started with a coaxial piston launcher with plans to use solenoid to trigger it. However if I fill it with propane in gas form (filling with bottle pointing upwards) it kinda makes a decent Bang. Then I filled it with the propane bottle upside down so the liquid can get in expecting more power, but the Bang was much smaller. I noticed the piston (with o-ring) gets a lot harder to move after use, I kinda have to lube it after every use.

[Moonbogg]

I'd use air personally for a pneumatic. Do the issues arise when using air?

[wyz2285]

No, with air is fine. However I'm just trying to learn the reason of it, plus I was hoping to use the launcher quite mobile, the portability of a propane can is interesting.

[Brian the brain]

Could it be because you can 't compess a liquid?Too much liquid in the system preventing parts from moving perhaps?

[Moonbogg]

I'm wondering if temperature could be the culprit. I imagine the propane being cold, and maybe it causes the piston housing to shrink while the piston itself has a different coefficient of thermal expansion, causing it to shrink less than the housing? If there are o-rings, they might stiffen as well due to the cold.

[wyz2285]

So I did more testing, the exhaust is too small and gas in liquid form does not flow and pilot the valve properly.
But even if I fill it will gas in gas form, the piston get stiff after not many uses, the o-ring gets really dry. Any suggestion for o-ring material? Or I should used two o-rings so some lube can be trapped in-between?

[Moonbogg]

Some pictures would help me to think..

[hectmarr]

Study the possibility of using a lubricant that enters the gas spray, similar to lubrication systems for compressed air, which is used in compressors. On the other hand, the solenoid valves that I have have a maximum and minimum operating temperature, and are for gases, and not for liquids.

[wyz2285]

I'll get some photos