What changes are normally expected in the vibration spectra of a screw-type compressor when it's on-load vs. off-load?
I would say you either have a screw-type or a reciprocating (piston) type compressor but that may only be me. In either case difference on/off load can and normally are significant as far as I have seen. Olov
Sorry, I meant screw-type. I've made the correction.
I wish to know what fault frequencies you normally find and how the amplitudes vary at the different frequencies, comparing off-load vs. on-load