What Are Positive Displacement Pumps?
There are two basic types of positive displacement pumps that are used today. They are the rotary and reciprocating electric positive displacement pumps. Both of these serve similar functions but work in different ways.
Rotary Positive Displacement Pumps
A rotary displacement pump works by using rotation. This creates suction or a vacuum that draws the fluid out of the hoses. This saves the need for having to do this manually which can leave fluids behind in the hose or pipe that may be missed. The rotation of the pump is very efficient as the vacuum created by the positive displacement vacuum pump is very effective at also removing air from the lines that may not be wanted and in some cases which can be damaging to the hose or pipe that it can be trapped in. Remember to regularly use vacuum pump oil to prevent friction in these types of pumps.
One issue with this type of pump is the clearance that is needed in order to get the rotary blades working properly. If there is too much room between the outside edge of the hose or pipe and the pump, it can leave room for the air or liquid to become trapped inside instead of vacuuming it out. This can also corrode the pipe or hose to the point where it is no longer effective for the job it was intended. Hook and claw positive displacement vacuum pumps are becoming more popular in industries thanks to the wide range of applications they can be used for.
The easiest type of rotary pump is the gear pump which has sprockets that fit into each other to create the rotation. They turn in opposite directions in order to create the vacuum which traps air and fluids. Screw pumps offer more complexities in their operation. These consist of two screws that have opposing threads which rotate in different directions. Moving vane pumps are the third and final type of rotary positive displacement pumps. These also have two parts that work in opposite directions in order to create the vacuum that is needed to clear the hose or pipe of air and fluids. Some of these pumps even come with a suction pressure control feature. An example of a rotary pump would be a rotary oil pump which is used to lubricate machinery.
Reciprocating Positive Displacement Pumps
This type of positive displacement pump uses a tapered cylinder that creates suction when the rotors are turned inside the pipe or hose. The liquid and air are pulled into the chamber that is created by the conical shape of the cylinders. This means less air or fluid is going to be trapped in the hose or pipe than if using the rotary pumps. These also go by the names piston or diaphragm pumps which are the same type of pump.
These are the most common types of positive displacement pumps on the market. They each have their own unique uses for clearing pipes and hoses of fluid and air. It is important to choose the right pump for the job when deciding to purchase a pump of this type. Make sure that all of the parts of the pump are in working order before using it as this can create issues down the road. These issues can be fluid still left in the hose or pipe or even air where there should not be any.
