Relief Valves On Cylinders

I am working on sizing the relief valves for a fleet of cylinders. The majority of the cylinders are DOT-4bw-260 cylinders. These cylinders are designed for refrigerant recovery but we use them to ship organic chemicals suspended in different solvents. I believe the relief design for these cylinders with our use is covered in DOT CFR 49 section 178.270-11. www.myregs.com/dotrspa

However if you use the simplified table given in the document to size the relief valves you just use the minimum of 12,000 SCFH . But by using the alternative calcuation that can be used for an exemption on a dedicated cylinder, you get a much higher flowrate for the design. I wonder if I am missing something here. The alternative calculation gives much higher flow rates than you get from using the API 521 calcuation Q=34500A^0.82 as well. Any thoughts on this?

I am also concered about the setting of the relief valve reccomended in DOT CFR 49 178.127-11. They reccomend a relief valve setting between 67 and 74 percent of the hydrostatic test pressure. However since these are DOT-4bw-260 cylinders they are hydrostatically tested at 2xMAWP instead of the standard 1.5xMAWP. Should I just set the relief to go off at MAWP with a max of 20% accumulation?

I am also concerned about the relief temperature. There is no design temperature for the DOT cylinders and I am worried about the temperature of the cylinder at relieving conditions. One of the solvents we use is toluene and at a vp of 215 psia the temperature is about 469F.
Does anyone know where these issues are addressed?
Is there any thing in the CGA-S1.2 document or in the CGA handbook about this?
I have been wandering around all over trying to get a handle on how to deal with relief on liquid filled cylinders with not much luck. I have been trying to contact the manufacturer but I have not been able to speak to their engineering department yet.
Thanks for any guidance you can give me.