A standard Plastic Lotion Pump usually has 6 parts.
Actuator – Made of polypropylene, also known as the pump head, its main task is to expel the contents from the lotion pump reservoir when pressed.
Closure - The entire assembly is secured to the neck of the lotion pump with the help of this assembly.
Outer Gasket - Usually made of low-density polyethylene or rubber, it helps prevent the contents from leaking out of the mouth area and is usually friction fit inside the closure.
Housing - Sometimes called the pump assembly housing, it keeps all the parts of the lotion pump in one place. The lotion pump housing also doubles as a transfer container for sending the contents from the dip tube to the actuator.
Internal Housing Components (Ball/Spring/Piston/Stem) - The internal housing components of the lotion pump depend on the individual product design and vary by manufacturer.
Dipping Tube - It is a long tube made of polypropylene that extends from the nozzle of the lotion pump to its very bottom.
How Lotion Pumps Work
Step 1 - The lotion pump functions like an air extraction device. It defies gravity and helps the contents of the tank reach the user's palm.
Step 2 - When the actuator is pressed, the piston moves, which in turn compresses the spring. It effectively allows the upwardly applied air pressure to pull the ball upwards along with the contents of the dip tube. The contents first fill the dip tube and then reach the lotion pump chamber.
Step 3 - Once the actuator is released, the spring is repositioned to its original position. The ball returns to its standby position and seals the canister, shutting off the flow of the contents so that it cannot return to the lotion pump bottle.
Step 4 - The three steps above are collectively referred to as startup. When the actuator is pressed again from its rest position, the container contents will first pass through the valve stem and then reach the actuator. Finally, the pump dispenses the liquid into the user's hand.