| 摘要 |
A dispensing pump having a unitary plunger defining a main pump chamber and functioning as a discharge valve upon accumulation of pressure causing the plunger to shift open, includes a container vent which is positively sealed against leakage therethrough even upon nudging the plunger during storage, shipment and handling of the pump. The pump includes a fixed position and a reciprocable plunger head having a discharge passage, the inside of the head and the top of the piston being complementarily contoured for expelling accumulated air from the pump chamber directly out of the discharge during priming. Otherwise, the pump chamber may be placed in communication with a vent chamber which opens into the container through the vent so that any accumulated air in the pump chamber may be vented into the container as an aid in priming. The volume beneath the plunger head may be enclosed as an air chamber so that the air therein may be vented into the container upon opening the container vent to assist in pump priming. And, the plunger is designed to effect a quick or a slow opening of the discharge passage. |
