[Paul Ewing]

OK, I got back home and checked my notes. According to Kimberly and GTT, at full blast the Cheetah uses about 22 CFH (10.4 LPM) at high pressures and 25 CFH (11.8 LPM) at low pressure. This means that it should do fair on two 5 LPM concentrators that are producing good purity at 8 to 10 PSI. I hardly ever run my Cheetah at full blast even doing work with 18mm boro rod.

So if you are not able to get an oxidizing flame, it probably means you are not getting good purity out of the concentrators or their PSI is real low. I just looked online and it looks like the Invacare Mobilaire V only puts out 5 PSI while the DeVilbiss puts out 8.5 PSI. I see two problems with this. One the 5 PSI is probably too low to work with the Cheetah well. Two and more probably, the DeVilbiss is overpowering the Mobilaire and back pressuring it. This would mean that it isn't contributing anything to the LPM flow and may damage the Mobilaire if done for long.

You might want to see what the brand of the 8 LPM concentrator is and look up the specs on it. IF it does in the 8-9 PSI range, it might be a good match for the DeVilbiss. You could dial back the LPMs on each to 4 and 7 or maybe a bit lower to increase the oxygen purity and be set for soft glass and fair size boro work.

We have a 5 LPM and 7 LPM setup that Angelique uses on her minor. I might try hooking the Cheetah up to that and seeing how it does. Probably won't be till tomorrow at the earliest though.