After a little bit of work and a lot of dialogue with different people in the compressed gas industry, the following position has been taken by Catalina Cylinders.
HM-220 has come full circle on the pressure relief device (PRD) requirements for oxygen cylinders. As currently written in 49 CFR 173.301(f)(3), ” For a specification 3, 3A, 3AA, 3AL, 3AX, 3AXX, 3B, 3BN, or 3T cylinders filled with gases in other than Division 2.2, beginning with the first requalification due after December 31, 2003, the burst pressure of a CG-1, CG-4, or CG-5 pressure relief device must be at test pressure with a tolerance of plus zero to minus 10%.”, compressed oxygen cylinders are excluded from this requirement since they are identified in the table in section 172.101(columns 3) as a division 2.2 gas. Current specification references were attained on-line at www.myregs.com/dotrspa/.
Catalina interprets this as:
New medical oxygen cylinders with the service pressures of 2015 psi and 2216 psi can be (and will be) equipped with the same CGA 870 or CGA 540 valves with the same PRD rated at 3360 psi +/- 10%. There is no requirement for valves with different rated PRDs to be used on 2015 psi and 2216 psi cylinders. This is the same as it was before HM-220 began.
Old 2216 psi medical oxygen cylinders (i.e the M6, M4, M2, M60, M90 and M122) in service with the (old) 3360 psi +/-10% rated PRDs will not have to have their PRDs changed out at the next requalification.
In preparation for what appeared to be an inevitable rule change, the +0 -10% rating of the pressure relief devices, Catalina Cylinders did procure and insert some valves in M2, M4, and M6 cylinders with pressure relief device rated at 3693 psi +0 -10%.These PRD’s are in compliance with the specification written either way, with either the +/-10% or +0 -10% tolerance on the PRDs, and are acceptable as is and will not have to be changed out at any time in the service life of the cylinders.
If you have any questions, please do not hesitate in contacting Catalina Cylinders.