Pressure relief valve blows at 80 psi. On a 150 psi valve

The over-pressure relief valve may be defective if the valve is opening before the desired tank pressure is reached. If not, then the shut-off pressure adjustment (if there is one) may be set wrong. You'll need to find out from the manufacturer exactly what static tank pressure the compressor is designed to provide and then determine if it is working correctly. If so, then the relief valve might be defective. DO NOT attempt to defeat the relief valve under any circumstances - it can result in compressor damage or a dangerous tank failure.

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The maximum pressure on most small compressors is 10 bar or 1000kpa which is about 145 psi in the old language most safety valves are set to 150 psi. I suggest you get some one to reduce the pressure switch setting. Running a compressor at elevated pressures does not give you any more air. A reasonable pressure for small compressors is 120 psi

The relief f valves are preset for something like 150 psi. I doubt you have that much water pressure. I would just replace the valve. There is NO adjustment.

More than likely a bad pressure switch or the orifice going into the switch is blocked.

Hi
your pressure switch is bad. so it isnt cutting off the compressor. the part number is N003306SV and can be obtained from Dewalt on Servicenet.
Detail

Good luck and hope this helps

From want you are describing sounds like the high pressure valves are leaking in the HP Head. there are 2 safeties on this unit . If the safety that's lifting is between the low and high pressure cylinders it's hp valves leaking. If the tank safety is lifting at 50-60 psi It should be replaced. It is a 200 psi safety.

I had the same problem. The relief valve loosened up after a couple years of use. Right around the center pin in the relief valve is a ring that has a slot in it that you can fit a small straight blade screwdriver into and tighten in a clockwise direction. This should tighten the spring on the relief valve and raise the pop-off pressure above the 150 psi setting of the cutout switch.

That is what the relief valve is set at, you need to
either increase the pressure on the relief valve or
reduce the pressure on the pressure cutout switch. Stephen

A pressure valve is not adjustable if you are trying to remove it for replacement it has standard threads. Clockwise to tighten and counter to loosing it. First though a pressure valve is the same as a relief valve it is for safety to keep from over loading you comperssor and blowing a head gasket or in extreme cases blowing up you tank. Be careful.

If you have the manual, check the compressor and normal pressure settings and ratings - 145 psi sounds high and unless you are using huge air tools. You may not need that kind of pressure. It sounds like the relief valve and motor overload are both doing their jobs to protect the system.