Hitachi EC-12 air compressor

[737182]

I have a Hitachi air compressor that builds pressure up to 120 psi or so. The compressor shuts off and the safety valve starts dumping pressure and it doesn't shut off until the compressor kicks back in. It just started doing this recently. Do I need to replace the safety valve or is it it something else? Any suggestions much appreciated!

[Tinkerdave]

yes that sounds like your safety valve. On compressors that shut of at 127 psi the safety valve should blow at about 145-155 psi.