Generator Recommendations

[Arkie]

The gen you are looking at does not have 220volt output to run the compressor at 220volts to drop the amp draw
for each leg of the output. You will have to go larger on gen size to get the 220v output on gen. Maybe go to a 5000w
gen.

Right, get a 220volt gen @ 5kw and then rewire your air compressor for 220v operation.

Just some thoughts for you to consider!

Also keep in mind (HEADS UP) that the smaller air compressors do not unload the compressor unless they make a complete cycle to their shut off air pressure. (because they unload using the pressure switch instead of a rotary mechanical unloader)
If your compressor does not unload the elec motor will stall (locked rotor) and let out the majic smoke from the gen and the elec motor)

I install a electrically operated pilot valve T 'ed into the pressure switch unloader line so as anytime electric to the compressor's electric motor is interrupted the compressor unloads. (the pilot orifice is open to the atmosphere with no electric to the motor)
Summary: A 5kw 220v gen should operate your 7.5 FLA/220v air compressor ok if you ensure that the comp always unloads. (10 amp time delay fuse in each 220 leg of the air comp will help protect your gen and compressor motor) Your comp elec motor will draw approx. 6 times the fla or 46 amps initial surge during start-up. (If the compressor electric motor stalls due to not unloading it will be locked rotor drawing at least 46 amps (+10kw) until something lets go. (majic smoke) Time delay fuses will allow initial starting of the compressor electric motor and then protect against running overloads.

Also if you get a auto idle genny, do not use the auto idle function when using the air compressor. Auto idle is not recommended when starting a electric motor because of the additional time delay in the gen coming up to speed will result in initial low voltage and high startup amps to the electric motor.

[Deere2me]

The gen you are looking at does not have 220volt output to run the compressor at 220volts to drop the amp draw
for each leg of the output. You will have to go larger on gen size to get the 220v output on gen. Maybe go to a 5000w
gen.

Right, get a 220volt gen @ 5kw and then rewire your air compressor for 220v operation.

Just some thoughts for you to consider!

Also keep in mind (HEADS UP) that the smaller air compressors do not unload the compressor unless they make a complete cycle to their shut off air pressure. (because they unload using the pressure switch instead of a rotary mechanical unloader)
If your compressor does not unload the elec motor will stall (locked rotor) and let out the majic smoke from the gen and the elec motor)

I install a electrically operated pilot valve T 'ed into the pressure switch unloader line so as anytime electric to the compressor's electric motor is interrupted the compressor unloads. (the pilot orifice is open to the atmosphere with no electric to the motor)
Summary: A 5kw 220v gen should operate your 7.5 FLA/220v air compressor ok if you ensure that the comp always unloads. (10 amp time delay fuse in each 220 leg of the air comp will help protect your gen and compressor motor) Your comp elec motor will draw approx. 6 times the fla or 46 amps initial surge during start-up. (If the compressor electric motor stalls due to not unloading it will be locked rotor drawing at least 46 amps (+10kw) until something lets go. (majic smoke) Time delay fuses will allow initial starting of the compressor electric motor and then protect against running overloads.

Also if you get a auto idle genny, do not use the auto idle function when using the air compressor. Auto idle is not recommended when starting a electric motor because of the additional time delay in the gen coming up to speed will result in initial low voltage and high startup amps to the electric motor.

Have you not heard of a combination check valve and unloader valve ? I'm thinkin' more small compressors use them rather than the PS type!

[Arkie]

Your question:
Have you not heard of a combination check valve and unloader valve ? I'm thinkin' more small compressors use them rather than the PS type!

Yes they are also termed Genie valves.

I've tried the genie valves. Never could get any long term reliable service life from them and had to keep a EXACT spare valve handy to keep the compressor at ready and would end up going to the Pressure switch type unloaders with the electric relay solenoid pilot valve connected to the load side of the pressure switch. The genie valve also needs to be sized wihin the cfm rating of the compressor.
If I see a cpmpressor with a bad genie valve I tell the guy what wrong with his comp and tell him to replace it himself, because I don't want my name attached to the repair. (a new genie valve going to fail again if the compressor lasts very long or is used very much)
You are correct in that they Genie type unloaders seem to be used mostly on the smaller and usually cheaper made compressors probably the factory thinking that the compressor will let go before the valve fails. (and their warranty is expired)