A Better Fix for Less?

A client called this morning inquiring about current pricing for 350psi (4L-292) cryogenic liquid cylinders (VGLs) and said his customer’s are requesting them instead of the 235psi (4L-200) VGLs he has been providing. Interestingly enough, he was also requesting repairs on six of his liquid cylinders with a note to be sure and check the pressure builders.

Possibility: End users have been cranking down on the pressure builders of his liquid cylinders to try and get more flow out of them.

The rub is that the flow from a DOT 4L-200 or a 4L-292 is just almost identical (+/- 300scfh depending on the model and whether you are vaporizing liquid oxygen, nitrogen or argon). So, higher pressure will not make higher flow. What will provide extra flow is to add some downstream vaporization allowing for a doubling or more of the gas withdrawal rate.

Suggestion: Put a hang-on Vap on the liquid cylinder at a cost of around $1000 to $2000. This is:

a) a lot less expensive than purchasing six new higher pressure liquid cylinders at $2000 to $3000 each;
b) actually better since it solves the problem which the new liquid cylinders would not;
c) and keeps the existing liquid cylinders in service and generating revenue.

Granted- this is assuming that the real issue is flow. We discussed visiting with the customer first to get a better idea of their application. There are just so many more applications that run at 80 to 110psi versus over 200psi means that it is likely they really don’t need 350psi liquid cylinders.


Pay a lot less and get what you really need? Hmmm.........

Large Tip Cutting Torch Oxygen Flow

Large tip cutting torches require high oxygen flow rates to operate properly. Flow rate requirements of +/- 1000 scfh are commonly encountered. It is also common for users to try and feed these large tip torches from a single liquid cylinder that has a vaporizing flow capacity of only +/- 300 scfh. The ineffectiveness of this has been discussed in previous articles, but never shown like this new video from Victor

http://www.jenobi.com/clientsites/thermadyne/video.htm

Hit the link and it should load right up. It provides a great explanation of the challenge of running large tip torches and the benefits of having proper liquid oxygen vaporization.

By the way- The side mount vaporizers shown are manufactured by West Cryogenics, Inc. and distributed by Eddie's Welding Supply and other gas and welding distributors.

Oxygen + Fuel Cutting- Starving for Oxygen

Good news- We have unprecedented access to information.
Bad news- There is too much information.

Frustration with large tip cutting torch operations is common. Tips burn up and results just aren’t what are expected.

Enter easy-to-use gas flow guides like those published by Victor. It only took two of us who knew what we were looking for about 30 minutes to find them today online. They are probably easier to find if you are one person with less presupposed knowledge…….. or not. You can also just drop by your local welding supply and pick them up.

Anyhow- check out the flow requirement for a #8 tip and you’ll see the oxygen flow needed for a type 303M, GPM, GPN, GPP is 450 to 500 scfh. Go to a Type 1-101, 3-101 (Oxy-Acetylene) and the oxygen flow requirement is 900-1050 scfh. Back in the day when your #4 tips system was fed by oxygen gas 16- packs everything was fine. The only problems were the weight, size and cost so you go to a liquid cylinder and all is fine. That is until a #8 tip is needed and no one ever mentioned that the maximum 8-hour flow rate from a 180 liter liquid cylinder is 350 scfh +/- depending on the manufacturer.

Result- A big powerful torch that is now starving for air which is kind of like a Ferarri with a wet air filter….. all show and no go.

Solution: Additional vaporization.
New Result: More air; More cut. Maybe even a speeding ticket….

Flow vs. Pressure- Boiled Frog Syndrome

Customer Y calls in January to ask about problems with his cutting torch work. “I just don’t understand. In August, everything seemed to be working fine. Now we are extra busy and my guys just can’t seem to cut like we were. We’ve turned the pressure builders all the way up, but that just doesn’t seem to help.”

Visiting, we find that several things have changed since August. He is, in fact, a great deal busier and now has 3 to 5 torches running off a liquid cylinder where he previously had 1 or 2. They’ve moved up to larger bore cutting tips and it is colder outside. All have combined to reduce the flow of vaporized oxygen gas that he is able to get to each torch.

This is a common and often misdiagnosed problem- especially where changes have occurred gradually or where users have switched sources from high pressure oxygen cylinders to cryogenic liquid oxygen. In many cases, the attempted solution is to increase pressure by going to high pressure liquid cylinders or cranking up the pressure builder on what they have. This sometimes makes the problem even worse by overflowing available ambient vaporization.

If the real issue is inadequate flow of gaseous molecules then the solution is often as simple as adding additional vaporization downstream. Very high use applications such as feeding multiple oxygen lances or large cutting tips might require you to link multiple liquid cylinders or go to a larger tank.

- Photo provided courtesy of Oxylance, Inc.