What is one of the most important pumps in the world for your area? Whether it be a house, a school, at work, or anywhere really. There are important pumps to think of. But one of them is the positive displacement pump.
But what is it?
This kind of pump is a constant flow machine. On the suction side, it has an expanding cavity, while the discharge side has a decreasing cavity. As the suction side expands the liquid flows into them and then flows out as the discharge side collapses. No matter the discharge pressure, it produces the same flow at a given speed (RPM).
Operating this pump against closed valves from the discharge pump is not advised since there is not shut-off head. The pressure in the discharge lines will increase until the pump bursts and/or severely damages if it continues to flow water.
What is absolutely necessary for this pump is a relief or safety valve on the discharge side. It can be internal or external. If internal, it should only be used as a safety precaution. While if it is external, it is highly recommended.
Whether it is a rotary lobe pump, progressing cavity pump, rotary gear pump, etc., this displacement pump still applies.
There are two classes: reciprocating and rotary.
Reciprocating
Usually, reciprocating pumps are plunger pumps and diaphragm pumps
Plunger pumps have cylinders with a reciprocating plunger. The head is where the suction and discharge valves are mounted. The plunger retracts in the suction stroke which causes the valves to open and allow the fluid inside. The plunger pushes the liquid in the forward stroke.
Meanwhile, the diaphragm pump has a plunger that pressures the hydraulic oil used to flex the diaphragm in the pumping cylinder. These kind of pumps is typically used when hazardous and toxic fluids are pumped.
Rotary
Rotary pumps are typically gear pumps, lobe pumps, vane pumps, progressive cavity pumps, and screw pumps.
A gear pump traps the liquid in between two identical gears and the chasing of the pump that is on the suction side that is opened between the gear teeth. While on the pressure side, when the teeth of the two gears rotate against each other, the fluid is squeezed out.
Much like the operation of the gear pump, the lobe pump has two lobes that are driven by gears that are external timing. The lobes, however, do not make any contact.
What consists of a progressive cavity pump is a metal rotor that rotates within as elastomer-lined or elastic-stator. The chambers from the suction end to discharge end are shaped when in between the rotor and stater, which makes fluid when the rotor turns progressive.
Now that you have got some information, you may want to check out your pump. And if you have anything you need to change then do not hesitate to do so! So get your positive displacement pump now!
