Hey
Please follow this link for catalogue http://www.swagelok....N/MS-01-141.pdf
I think they are not compliant with regards to hydrocarbon service. They are ok for chemical injection systems (methanol / CI /PPD).
Check out the catalogue an d see what you think.
cheers
To clarify, the issue is that the valves are not capacity certified so that they do not comply with the ASME BPVC and you won't find them listed in NB-18 over at the National Board of BPVI:
http://www.nationalb....aspx?pageID=64
where orifice diameters and coefficients are documented. When doing a rating or final design relief calc, this is the data source I refer to rather than any other basis.
So, if you use one of these non-code compliant relief valves then you need to understand the limitations of what you've got. API STD 520 Part 1 (referring to the 9th ed at 5.9) has a methodology for liquid relief of non-capacity certified relief valves but not gas.
All this style of relief valve are (as best as I can make out), in effect, a sprung loaded control valve. So, for sizing, the current technical data from Swagelok does not provide sufficient useful information, in my opinion. I say this because I'm dealing with the exact same issue. What I want to know is the flow characteristic or flow resistance of the valve at full lift, i.e. conditions relevant to sizing when a capacity check is involved. All Swagelok give you in their current catalogue is an orifice diameter. This is of little use without its associated orifice coefficient.
I did find some old 1994 catalogue data here:
http://50.244.15.10/...lief Valves.pdf
Unfortunately, it's for an R4 not an RL4, but it does show that at higher inlet pressures the flow rate that the valve will pass reduces. The problem with the current Swagelok data is that if you chose to extrapolate the flow curve, then you'll end up with the wrong result. Given that I've got nothing better, I'm using the quoted Cv for my work on the expectation that the key difference between the R4 and RL4 is around the installed spring. I'd be happy to get better data if anyone can offer it up.
If it helps, I also found the RL3 data sheet here:
http://50.244.15.10/...lief Valves.pdf
I'd also suggest that when working with uncertain data sources such as this, that the approach offered by API STD 520 Part 1 at 5.12 is a sensible strategy and that is to work to a relieving capacity at a reduced flow factor.