Thursday, February 16, 2012

Studio Design - Oxygen Systems


Here is another thing you really need to know when building your own studio.

Oil and Oxygen are a bad combination. Don't mix oil and oxygen. Ever.

Don't oil your oxygen fittings. Don't lubricate anything with oil around pure oxygen. Do not oil your fittings. Don't store oil near oxygen. Got that - tattoo it on your soul - no oil and oxygen.

I say this because I have known it for so long that I assume everyone knows it, but apparently not. Welders know it - they were taught it when they took the welding course.

Here's another tip - not all gas fitters are welders.


Ok - let's move on to more positive information. I was recently involved in a studio move and re-design (hence the paucity of posts lately!). One of the criteria was to streamline the look and function of the studio by moving the oxygen tanks outside of the actual flameworking studio.

In the past, a single oxygen tank fed a pair of torches - so when the oxygen ran low, you needed to stop two torchers and swap out a tank - which meant - for the six stations that were there, you needed three tanks in use, and at least three in reserve, and probably three empty for pick up, for a total of nine tanks in rotation. That's a lot of storage, and lease fees, and you still  have students running out of oxygen mid-bead if you don't watch the gauges.

We wanted a better solution.

What we planned, therefore, was a manifold to hook up multiple tanks in another room, and a pipe to run into the room, and to near each workstation, and hoses to make the final jump to the torch. One system, mulitiple tanks - no running out of oxygen.

What kind of pipe to use? We were concerned with two things - one being the material that the pipe is made of, and the other was the size - diameter.

What the pipe was made of was significant in that we should have no undue reactions or corrosion from the oxygen, and size in that it be large enough that there is still sufficient pressure at the end of the run. Size does matter. ;-)

A long run of hose or pipe will reduce flow just through friction - and if you don't believe that - replace your garden hoses with 3/4 inch hose and see what a difference it makes when you water the lawn. I had already noticed a very large difference just in the varying hose lengths that we were using. (Tip - don't have your hoses longer than they really need to be.)

We went with "Black Iron" pipe - because that was what was being run for the Natural Gas that was also being piped into the room. The Natural Gas comes from the city pipes, but is not at sufficient pressure to run 6 torches, let alone 8 or 12 - and so it runs through a booster - which is fairly noisy - and we wanted that out of the room too. While I personally prefer Propane for working glass - sometime Natural Gas is just easier. And you never run out.

But what we didn't realize was that Black Iron pipe - and for that matter, pretty much all pipe unless specified otherwise - comes with a light coating of oil to prevent corrosion. Remember what I said about oil and oxygen?

The pipefitter did a brilliant job running the pipe, setting it up and installing it - very neat and well planned - built the manifold, valves, etc. Assembled it all with a sealant known as "dope." Remember what I said about not all gas fitters are welders?

Dope - pipe sealant - is a non-hardening paste that ensures a gas/air tight seal and says on the container "NOT FOR USE WITH OXYGEN SYSTEMS." It contains oils to keep it flexible and prevent it from drying out and hardening and no longer being an effective sealant.

Fortunately - the gas fitter went ahead and hooked up the lines to the torches and used rather a lot of dope to seal the fittings. And when we saw this - his rather generous use of dope on the B fittings (which don't need dope - more on that in another post) - got us thinking about the dope, and then saying - wait - if he didn't know that - then what else didn't he know? ... It got us to look much closer - realize that the entire system had been sealed with the dope, and ... this was a problem.

In the end - we had to have the oxygen line disassembled, the dope cleaned off the fittings, reassembled using orange Teflon tape (rated for oxygen) - and then flushed with a hot water and TSP (Tri-Sodium Phosphate) solution, then flushed with clean water - then blown out with air to dry out the lines. The TSP flush is the procedure to remove the oil coating from the pipe. (As the pipe was already in place, we set up a barrel with the hot TSP solution and a hose attached to a transfer pump (an inline pump, like a waterbed pump works) - and a hose from the other end running back to the barrel. The solution was pumped through several times, then again with the clear water flushes. Not really a big deal.)

So - lessons learned.

  • Oil and Oxygen do not co-exist
  • Not everyone knows this
  • Assume that the pipes have an oil coating and have it cleaned
  • Ensure that the joins are sealed with teflon tape (Orange - rated for oxygen.)
The system is now oil free, safe, and working beautifully.

If we were doing it again, we think we would opt for a brazed copper pipe for the oxygen (all the useful information showed up after the choice had been made!) - but we would still have it cleaned to remove oils.

The good news is that the diameter of pipe we chose is brilliant - and we have great oxygen pressure and no variation in pressure/flame as torches are turned on and off.

I'll get you some pictures of the system and set up in case you need ideas for your own system. 

(The whole thing is a tad embarrassing - wish we had all the right data at the beginning of the project! But I publish it so that you don't make the same mistakes.) 

1 comment:

  1. Thank you for this tremendous information. I may be in a position in the next couple months to set up a real torch and this is being bookmarked, saved and dedicated to memory. Just in case, I'm taking a pen and paper and writing it down too. I know oil and O2 don't mix and I know there is such a thing as gas teflon tape, but I didn't know how to clean oil out of pipe (seems stupid, really) or what was involved in setting up. Thanks!