Abstract: A one-time use, disposable, plastic-molded locking clip is provided for retaining the depressible plunger of a dispensing pump in a fully extended position during shipment or otherwise. The clip may be snapped onto the plunger after the latter has been fully assembled, yet once installed, the snapped together portions of the clip are not readily detectable nor accessible so that the clip may not be removed without destroying the same by tearing a twist tab therefrom. The generally C-shaped jaws of the clip embrace the plunger immediately below the head thereof in order to block depression, and such jaws forceably interlock with each other into a complete loop so that the clip may be installed upon pumps devoid of structure which would assist in locking the clip in place.

Abstract: The plunger may be locked down after a full depression stroke so that the overall height of the pump assembly and the container with which it is associated can be significantly reduced. A special valve component loosely encircling the plunger and slidable with friction along the interior surface of the barrel is initially positioned during factory assembly in a closed position covering vents in the sidewall of the barrel, thereby blocking the undesirable ingress of liquid into the barrel above the piston should the container be laid on its side during shipment or other handling. Upon the first unlocking upstroke of the plunger to its extended position, a shoulder on the plunger lifts the valve to an open position so the vents can function properly to introduce ambient air into the container replacing pumped-out product.

Abstract: The plunger may be releasably locked in a fully extended condition against depression by an annular locking disc which receives the plunger and has a series of radially inwardly projecting, circumferentially spaced, plunger-engaging teeth snapped into a notch on the plunger. The teeth are slightly outwardly inclined in the direction of plunger extension, and stationary structure on the pump adjacent the plunger cooperates with the teeth to prevent them from being reversely flexed when depression of the plunger is attempted, thereby securely locking the same in its upwardly extended position. By gripping a tab on the disc and flexing it upwardly so as to reversely flex at least certain of the teeth, attempted depression of the plunger while the teeth are in that condition will release the plunger so that full depression may continue.