air compressor pressure relief valve

[Dave Fritz]

What is the size of wrench needed to remove a pressure relief valve on an air compressor. A 9/16 is a little loose and no metric I have is any closer. People tell me they use an adjustable wrench. I can't believe they're not a standard size.

[Bill Dufour]

Not 17/32? Measure it with your calipers.
Bill D

[lowell holmes]

https://search.yahoo.com/search?fr=mcafee&type=E211US739G0&p=crescent+wrench+picture

[Myles Moran]

When I replaced the drain valves on my compressor, i couldn't get a wrench that'd fit and let me turn hard enough to loosen them - the valve wanted to deform instead. I used a pair of channel locks to remove the valve (and beat it up in the process) - some self locking pliers or a pipe wrench would do the job just fine here. The 9/16 was good enough to get the new valves in and tight enough to not leak.

[Bert McMahan]

I can't recommend the Knipex pliers-wrench enough for this kind of thing. They are every bit as good as everyone says they are.

[Myles Moran]

I can't recommend the Knipex pliers-wrench enough for this kind of thing. They are every bit as good as everyone says they are.

Yea, there isn't much that the pliers wrench or the cobras can't handle. 10" is a great go to size.

[Bill Dufour]

Steam locomotives have three pressure relief valves. Set like 5 psi apart. That way you know if the two lower pressure ones are set too high.. They should blow in order from low to high.
Bill D

[Carl Beckett]

I have even used a pipe wrench for such a thing (buggers up the flats but it isnt anything that goes on/off very often)

[Ole Anderson]

A small pipe wrench is invaluable. The harder you turn it, the tighter the grip becomes. I even have one only 6" long. And I have one 24" long, and several in between. You can only clamp a set of vice grips so tight.