[Peter Matteson]

Originally Posted by ayeckley

I believe you are correct. McMaster-Carr 8088K14 seems to be the best fit for this application. They seem to be intended for water as the working fluid, but usually air is acceptable as well (a call to McMaster should verify this). Unfortunately, the miniature nylon relief valves are only rated to 10psi and are not truly "adjustable".

It's not clear (to me, at least) from the rule change if a backpressure regulator such as 99045K11 would be legal or not.

I was thinking more along the lines of http://www.grainger.com/Grainger/items/6D915?Pid=search

It's smaller and lighter than what you were looking at.

I'm not sure about the back pressure regulator's legality or if you would want to use it. The p/n you list will constanly bleed air keeping your compressor running constantly. I would just use a second regulator and adjust the pressure down.