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DOT cylinder Relief valve expert

DOT cylinder Relief valve expert

DOT cylinder Relief valve expert

I am looking for someone to do some sizing on relief valves for Department of Transportation (DOT) cylinders.  I have looked at all the DOT paperwork and I am baffled at what I need to do to be covered.  I want to turn it over to an expert. But where do you find this guy?

Any suggestions other than just "Google" are welcome.


RE: DOT cylinder Relief valve expert


As usual, you've quickly boiled down your problem to the hard-core, practical realities of the application.  I strongly agree with your deduction that when dealing with the Department of Transportation regulations, one should rely on an expert who's been there and back.  Fortunately, my experience with DOT cylinders has involved existing relieving devices already in place - and sanctioned by the DOT.

I would recommend that you contact an agency that works day-in-and-day-out with the DOT: the Compressed Gas Association.  I'm willing to bet they know who the guy(s) that have previously sized the many relieving devices are - and where they are at presently.

The CGA is cognizant of the many hazards involved in transporting chemicals across State lines and they can appreciate the technical, engineering problems involved.  I would expect a more technical and practical response from them than from a bureaucratic organization like the DOT.  Nothing against the DOT; they're trying to do their job.  But the CGA has to confront the actual applications every day.  They stand a chance of helping you identify the person(s) you need.

Good Luck.

RE: DOT cylinder Relief valve expert

For cylinders that will be in transportation DOT references the standards produced by the Compressed Gas Association. For cylinders less than 1000 lbs. water capacity apply the requirements of CGA S-1.1, Pressure Relief Device Standards - Part 1 - Cylinders for Compressed Gases. If the cylinder water capacity if > 1000 lbs., CGA S-1.2 would be applicable.

If you provide a little more detail I may be able to help you. Or you may download the standards for a nominal fee at www.cganet.com

RE: DOT cylinder Relief valve expert

I have the CGA standards.  The real problem is that the materials are flammable liquids, not gases or even liquified gases.  They are shipped in cylinders instead of drums because we add an air sensative chemical to the solvent (less than 10%) and have to keep nitrogen on top of the mixture to keep it inert.  
That is where the problems come in.  We are not exactly in any catagory of the DOT regulations and CGA is really only interested in gases.  Hopefully they know of someone with more experience who can help deal with this.


RE: DOT cylinder Relief valve expert


Just an afterthought, in the form of a question:

If you have the opportunity and do, indeed, contact the CGA for help on this, could you keep us informed as to the results?  I'm very interest in the response and help you obtain on such a practical and useful application.  I'm not interested in finding out the specifics on the name(s) of experts, how to do it, etc.  I mainly would like to know if this professional society is up to helping out engineers in their pursuit of resolving problems - like we are (except we do it for free).  Are they pro-active in trying to help out on this problem?  Your opinion, on the results obtained, would be very useful to others on this forum - especially those that contribute to the CGA as members through their company.

Art Montemayor

RE: DOT cylinder Relief valve expert

Is CGA helpful?  We noted a change in the formula for gaseous storage vessels that would result in a substantially larger relief device.  In September, 2003, we asked them:

"I have a technical question regarding the minimum required flow capacity equation for uninsulated containers for nonliquefied gases.  

We have sized many relief valves using the equation from CGA S-1.3-1980 in section 5.3.2 Qa=0.029Wc.  (Wc is water capacity in gallons).  Since the equation has changed in CGA S-1.3-1995 in section 5.3.1. to Qa = 0.00035PWc (P is relief pressure), does the CGA recommend that the relief devices be resized accordingly?"

We're still trying to get an answer.


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