What the other guys said. I have a 3M AccuSpray gun that I tried to use on a 50+ year old 2 hp compressor I drug up here with me from CA in 2019. I painted a car or two with it and a suction feed Craftsman gun that came with the compressor back in the 60's, but it would not keep up with the HVLP gun. Even though the HVLP needs only 20 psi at the gun, there wasn't enough actual compressor capacity. I believe the 3M AccuSpray needs in excess of 6 SCFM. I bought a 60 gallon 5 HP compressor after that first attempt.
I believe Tim is referring to a gun with compressor built in, or a turbine air delivery system, but he'd have to confirm that.
Bottom line, unless that 7 gal compressor has a honking big compressor on it (and appropriate HP motor), it's not going to support a HVLP gun.
