A suction apparatus seal for portable paint spray guns having a suction apparatus received via mating conical surfaces in a salient inlet port, the seal formed of resilient, low-density polyethylene and having a radially inwardly directed lip sized to seal around the suction apparatus and a cylindrical mediate section sized to seal around the salient inlet port and a radially outwardly flared flange to aid in installing the seal on the inlet port of the spray gun. The seal also provides positive engagement of the suction apparatus when it is initially loosely engaged with the paint inlet of the gun.