Most lotion pumps have two different pumping methods. The first is called capillary action, which allows the lotion to travel up the neck of the bottle without any leaks. The second method is known as air compression, which pushes the lotion through the nozzle from the bottom up into the container. Both pumping methods work great, but each has its pros and cons. Which one you choose depends on what kind of liquid you are attempting to fill and how large the bottle is.
The two main types of lotion pump available are rotary screw pumps. Rotary screw pumps use a metal spring that turns when a small amount of lotion is poured into the bottle. When the lotion is completely dispensed, the metal spring flips over and fits against the side of the bottle. The piston moves up and down using the oil or grease that was previously pumped into the bottle. Because the piston moves using metal coils, there is a danger of the piston poking itself into your eye if the lid is improperly closed. This is easily prevented by ensuring that the cap is secured and the cap is properly attached.
Larger pumps also use other kinds of pumps for lubricating the moving parts. One type is known as dip tube pumps. This type of pump uses a metal tube with a hole in the middle. Inside the tube is oil or grease that is compressed and moved up to the top of the hole in the tube. A small pump, usually around the same size as a lipstick applicator bottle, forces the lubricant up the tube toward the top of the hole so that the lubricant can spread out over the entire tube area.
A third kind of lotion pump is known as foam dispenser pump. This is a little different from the other two because it is not a cap-and-stack mechanism. Instead, an actuator is a cone-like object that holds a small amount of liquid in its tip. When the tip of the actuator tip is squeezed, the liquid travels through the cone area and the tip then squeezes the liquid back into the reservoir.
Finally, there are some actuator-type pumps that are made using a material called polystyrene (PPS). This material is similar to Styrofoam, which is often made into cups and bowls. The only difference between the two is that PPS is much harder than Styrofoam and so it does not yield as much to gravity as the former does. Because of this, the volume of the dispensed liquid remains more constant as it travels through the actuator instead of being randomly distributed in different areas inside the reservoir.