Tools, Sharpening and Power Machinery - Air Compressor Safety Valve Replacement

I picked up an old Craftsman 3 hp, 30 gallon, twin cylinder, oiled compressor going back to the late 1970s. It seems to be a rugged piece of machinery and and in pretty good shape. One problem though: the safety valve blows before the motor shuts down at 125 lbs. I adjusted the pressure switch back to about 120 lbs, and now the thing operates as it should. I guess the safety valve is worn and needs replacing. It is rated at 140 lbs, but the only replacements I've been able to find are either rated 125 lbs or 150 lbs. I assume that a 125 lbs valve would keep on blowing before the pressure witch has a chance to do its job at 125 lbs. The tank looks to be in good shape, but, of course, I have no idea what it looks like on the inside. Would it be safe to go with a 150 lbs safety valve, or can anyone steer me to source for 140 lbs safety valves?

Thanks.

If it's an older unit it is likely that it originally was set at a 100 psi cut-out.
It is only recently that consumer compressor units have pressures higher than 100 psi.

Most air tools are designed to operate at 100 psi and the rise in pressures IMO has been driven by marketing and not necessity.

most commercial truck type shops use 150psi and have for years, because a lot of truck tires run at 120psi., home use 100 is fine will do virtually anything you could ever need.

murphy was an optimist.

Greg,
This one has a 230 v. motor and the manual says it's 95 psi on and 125 psi off. If I understand you and Speedwrench correctly, you are both telling me to leave it the way I have it now, with the cut-off at 120 lbs, or a little lower, and the 140 psi rated safety valve blowing at around 125 psi - all that assuming the pressure gauges read accurately, which may well not be the case. Thanks for the input. The more conservative approach makes sense. That's what I'll do.

Vander,

I would suggest that at the least you replace the gauge.
This would give you a better idea of where the problem could be.