What Is A PCP Pump?

What Is A PCP Pump?

Last updated on June 4th, 2021

A PCP pump is a type of positive displacement pump. Breaking down the acronym, PCP means progressive cavity pump, but it also has other names like progg cavity pump, eccentric screw pump, or just plain cavity pump. It is important to know these different terms for progressive cavity pumps as PCP can often mean other types of pumps, as the acronym PCP is used very often in the pump industry.

All these words that we have gathered mean the same thing though, and that is that the pump transfers fluid, and it does so by using a sequence of small fixed shaped cavities that turns as the pump’s rotor turns. 

Imagine a screw being drilled. The screw’s ridges help the process of getting the metal in the material you are screwing, by grabbing the material and using the ridges to help cement it in that area. With progressive cavity pumps, the screw is the liquid, the ridges the pump, and the material is the area which you are trying to remove water from or put water in.

But the process is the same. Of course, this explanation is a simple one and if you want to know more about how progressive cavity pumps actually work, we will be diving into that now.

How do Progressive Cavity Pumps Work?

As we said before, progressive cavity pumps are a type of positive displacement pump, which means that the PCP has a suction feature that is connected to an elongated case. Inside this casing is a rotor, or a “worm” rotor. This rotor is shaped like a helix,  meaning it twists. This creates empty spaces in the casing which can be filled with liquid.

As the rotor moves, a temporary seal is created holding that water into the empty space. The rotor then continues to move, and in doing so pushes the fluid it has sealed up through the pump. With each turn, the pump picks up more liquid, seals it, and moves it through the pump until the sealed material reaches the discharge port. 

What is a progressive cavity pump used for?

Progressive cavity pumps are normally installed in places where a high flow of liquid or a high flow pressure needs to be changed to a smooth or lower pressure flow.

In plain terms, you could use these types of pumps to remove water from your garden after a flood, or in less dramatic circumstances, you can remove or return water to a hot tub when you are ready to clean it. And the same goes for pools, ponds, aquariums, or any body of water that you need to move to or away from. 

An example of a progressive cavity pump is the SumpMarine Water Transfer Pump. It is designed for household use and can be used to empty out or fill up pools, fish tanks, and similar sized home items. It can also be used to pump water from your hose pipe, giving you more pressure than a non progressive cavity pump would give. 

How do I start up my Progressive Cavity Pump?

The first thing you should do is put the progressive cavity pump’s suction into the liquid. This is because you should never run a progressive cavity pump without water. Even a few seconds in a dry condition can damage the equipment. Once you are sure the suction section of the device is in the water, you should open up the vents and values.

Lastly, you want to make sure that the direction you want the fluid to go in has been set correctly. This would be easy enough, as you should be able to do this by switching the pump motor. If you’re not sure how to do this, it should be clear in your progressive cavity pump’s manual. Once you have done those steps, the progressive cavity pump can be ready to use. 

What is the difference between a 3 stage and 4 stage PCP hand pump?

A PCP hand pump is different from the PCP pumps we have been talking about. In this situation, PCP stands for Pre-Charged Pneumatics and it means that the pump is ready to go when you pull the trigger. Pre-Charged Pneumatics are often used in airguns and you can see this from the word “Pneumatic” which means air powered.

The Pre-Charged Pneumatics use air instead of water and are completely different from cavity pumps in purpose. Their job is to create bursts of high pressure to fire the pellet gun or even a scuba tank.

Three stage and four stage pumps are very similar. The real difference between them is to do with their PSI rating, or pounds per square inch. This tells you how much the pump can be compressed. On average a four stage pump will have a higher pounds per square inch rating because it has an additional stage in the pumping process.

The 3 stage compressor, on the other hand, tends to be simpler machines and needs less volume of air to be compressed. This makes them cheaper to buy, cost less to use, and easier to operate.

Most manufacturers limit the pressure a stage can have. This is so that the pump can stay at its optimal pressure level, so the more stages you have the more pressure can be used and the faster you can pump.  All in all, you should buy the Pre-Charged Pneumatic that the air gun or scuba set suggests, as it would have figured out the appropriate PSI rating needed.