Using Pressure Gauges on Oxygen Service?

I think you meant trichloroethylene/trichloroethane, the common solvents.

tri chlorotrifluoroethylene is a gas used to make plastics.

I have to give you a GA for providing a more complete answer than mine.

Hi Aman

Your gauge may also not be suitable for oxygen service if it is oil damped (ie the gauge face with the needle on it is submersed in silicon oil). Albeit that the oxygen should not normally come into contact with the silicon oil, there is still the potential to create a bomb!

FYI if the gauge IS oil filled, never situate the gauge in such a way as to point directly at anybody as, if the Bordon tube bursts, the oil cannot escape from the emergency vent hole quickly enough and this may rupture the glass face sending shards of glass into someones eyes etc!

Good luck with it!

Drew hit it on the nail head - any combustable debris left in the bourdon tube will ignite when exposed to oxygen. also seals have to be compatible with oxygen. Low pressure gauges may use mechanism that employ elastomers, so if oxygen cleaning is required those seals have to be compatible with both oxygen and the cleaning methods.

Al

If so, and the label is removed, then how do I know wheter a guage should be used on oxygen service or not.

If there is no label, don't use it in oxygen service. Personally, I wouldn't use any part (gauge, valve...) that didn't say "cleaned for oxygen service".

As i underdstand it the actual mechanism that causes the combudtible material to ignite ( and blow up the gauge ) is not fully known. Just having combustible material in a high oxygen atmosphere doesn't mean it will burn or explode. One theory is that small particles of dust in the gas cause a spark as they are driven a high speed past a corner or 'rag'. I know that gauges do blow up but i don't know if it is restricted to when they are first turned on with the sudden rush of gas or whether they just blow up in use. This may be one for the Mythbusters.

Hi Jimrat

As i understand it the actual mechanism that causes the combudtible material to ignite ( and blow up the gauge ) is not fully known.

I think that the mechanism is very well understood in that you must have EXACTLY the right proportions of oxygen to fuel vapour for there to be a chance of explosive ignition (thus limiting the likelyhood as, seldom are the proportions exactly correct).

As for the ignition side, you only have to understand the principles of a compression ignition engine!

G'Day beej50,

Yes i do understand the compression ignition effect which is why i think that the gauges may explode when they are first turned on, i.e. when the bottle valve is opened quickly.

I agree with you that the mixture has to be correct for combustion/explosion to occur making it all seem rather unlikely. Also the Joules Thomson effect would tend to indicate that the internal temperature in use would preclude compression ignition. I am sure you have also seen gauges dripping with condensate or even iced up.

If you know first or even second hand of an exploding gauge can you verify when it exploded?

During the war in Turkey, my father sent Acetylene tanks to be refilled, they came back (unknown to anybody) some filled with Oxygen (as mystery how they had not exploded already!). A colleague of my father took mone, craked the valve to see if it was full and was instantly killed as the cylinder simply exploded.

My father had to rig up a jury mechanism and a deep pit to test each cylinder, several more exploded ......

I would say that Oxygen is the single most dangerous gas that is in common usage.....

A colleague of my father took one, craked the valve to see if it was full and was instantly killed as the cylinder simply exploded.

i really do not understand how this is possible.........

If there was enough flammable gas left in the cylinder when it was filled with oxygen then there is a chance ignition will occur as the gas escapes. During my USAF Fuels technical training we were shown videos of vapors being ignited by air / fuel vapor mixtures passing through and oriface. We were instructed that static can build up due to particles in the air and cause the ignition.

Perhaps someone else can describe in detail exactly what happens to cause the static discharge or another method that could have caused ignition.

Drew

Neither did he, but do not forget, it was an acetylene cylinder, wrongly filled with Oxygen.......that should answer your query (provided you are trained in Oxy/Acet welding....or in the use of Oxygen and its dangers.....if you are not, then you may not understand the problems....

There is solid porous material (stabilization) in acetylene cylinders and a solvent is added as well (acetone or DMF - dimethylformamide) to increase solubility/capacity. There could very well have been residual C2H2/solvent in them. With O2 in there a < LEL or > UEL condition could very well have been reached. On opening the valve, friction of the escaping gas could causes a static spark, and, if the flame propagation velocity through the valve was greater than the velocity of the escaping gas mixture, BOOM!

It's too bad it didn't happen when they were being filled! No justice!

Mike

It is because the oxygen gas has group into flammable gases category. Therefore, all instruments or equipment or parts used on oxygen gas system must be explosion proof. Wrong application of instrument may lead to serious accident happen. Anywhere, most of the personnel they are not aware of it (flammable gases), therefore normally supplier will make some remarks on the instrument that not explosion proof component.

It is my understanding that high pressure oxygen and any hydrocarbons inside the pressure device would explode upon contact.