Adjustable pressure relief valve?

[ayeckley]

In Team Update #5, rule <R72> was updated to mandate the use of an additional relief valve when solenoid valves with "maximum pressure ratings" less than 125psi(g) are used. Interesting that they didn't specify a relieving capacity (presumably they intend that it should be greater than the compressor max flow rate).

The bigger issue at-hand however is: where to find reasonably priced, properly sized, adjustable pressure relief valves? SMC doesn't appear to have anything other than residual pressure relief valves (which aren't the type of relief valves the GDC is referring to). I didn't find anything made by Festo either. Parker has some marginal candidates in their instrumentation product line, but they are still a bit too large and expensive. So far the best option looks like something from Swagelok, but they will still be relatively expensive.

Anyone found a better option yet?