Equipment for delivering liquid, particularly oil burners

Claim 1

A pump assembly comprising, a gear pump of the type which forms a group of expanding inlet chambers and a group of contracting outlet chambers on opposite sides thereof, said pump having a predetermined delivery pressure, inlet and outlet means for said pump, a pressure regulator having an inlet connected to said pump outlet, said regulator having a main outlet and a bypass return outlet, liquid feed means between said groups of expanding and contracting chambers in the region of greatest chamber volume, said liquid feeding means supplying said chambers in the region of greatest chamber volume with a liquid from said pressure regulator having a pressure between atmospheric pressure and said delivery pressure, a return pipe for returning liquid to a sump connected to said regulator bypass return outlet, valve means in said return pipe openable at a pressure substantially equal to said liquid pressure, conduit means on the upstream side of said valve means extending from said return pipe to said liquid feeding means, said valve means having throttle means extending from the upstream side thereof to the downstream side thereof, said throttle means presenting a greater resistance to pressurized liquid than to pressurized air.