Is it possible to store air compressor filled without damage from water?
Pressure tanks are usually steel, steel is somewhat flexible, it stretches a bit when filled, if the tank is left full it can shorten the life of the tank, I used to have a small scuba shop and did tank inspections as required annually, with hydrostatic testing every 5 years , the recommended pressure for long term storage for all tanks was 500 psi this is for tanks that range from 2200-3500 psi working pressure. I once purchased 4 steel tanks that had been sitting for close to 15 years at 3300 psi they were 3000 psi tanks, I dumped the air and had them hydrostaticly tested in fact all 4 tanks passed by enough to get the + rating that allowed them to get the 10% over fill. After that I did not pay much attention to that guide line but did tell my students the guideline and my experience so Can it be left full sure it may shorten the life of the tank , just make sure to blow the water out of the tank prior to letting it sit full of air.