Among the models of competent pumps, a self-priming pump is a device, executes both air and water-based mechanisms to start the pump. For getting a required fluid, the specific technology of this device mixes water and air.

And until the device becomes wholly primed, it creates this mixed fluid for operation. A self-priming pump makes its air passages clean before starting the pumping.

General Facts of Self-priming Pump

Self-priming Pumps Run Dry or Not?

To start operation, a self-priming pump needs fluid in the casing. It can not run dry anyway. Dry running of this device causes severe damage to the mechanical seal. And this kind of damage leads to a complete pumping system failure. So, without completing the simple step of fluid circulation, the mechanism does not allow the pump to be started.

And this self-priming mechanism executes a few steps to start the pump. First, inside the pump’s casing, you need to fill fluid. Then the pump’s mechanism mixes water and air to the suction line.

The forced exhausting of air makes a low-pressure space inside the impeller. At the moment, atmospheric pressure forces the liquid towards the suction line to fill the low-pressure area. After the air’s final movement, inside the suction line, the self-priming pump starts to operate healthily.

If you plan to install this pump, always remember only the initial filling of fluid, can move out the air of the suction line.

Is a Foot Valve Necessary For the Operation of Self-priming Pump?

In the ordinary conditions of operation, a self-priming pump does not need the foot valve’s equipment. But the conditions of frequent activities within a short time based on self-priming requires a foot valve. The primary purpose of the foot-valve installation is to maintain a standard quantity of water in the pump’s passage.

Are Positive Displacement Pumps Run On Self-prime Mechanism?

The purpose of applications and potential equipment defines the matter of the self-priming mechanism for a pump. As per general concepts, a positive displacement pump works as a self-priming pump.

For instance, the diaphragm pumps run on-air operation follows the mechanism of a self-priming pump. Because the action of air for the operation of a diaphragm pump creates pressure contrast in the chamber. As a result, this whole mechanism draws the fluid into the chamber of suction.

Working Principles of a Self-priming Pump

The actions depend on the innovative technology, lying on the equipment of a self-priming pump. The casing of this potent device consists of two passages – larger and smaller.

These two make a spiral scrolling segment and a cavity holder at the end of a discharging point in the cylindrical spout. These features act to execute the entire mechanism of a self-priming pump following the below functions:

Circulation Flow

In the spiral scrolling segment, the discharged water of passage – A, comes back to the impeller through the B-C passage during self-priming. It acts as an initial self-priming process. After completing this process once, the discharge of water in the passage is repeated.

Bubbles Removal

The repetition of water circulation through the passage mixes air and water in the middle segment. Then mixed fluid becomes intensified in the crucial vortex D inside the impeller. And finally discharges it into passage A of the self-priming pump.

Separation of Water and Air

During flowing from passage A towards discharging nozzle B, the air-water mixed fluid faces a cyclonic force. And in this entire phase, these two factors become separate automatically by the centrifugal force.

And then, the water follows the re-circulation process in passage B – C. Now, after separation air reaches the cavity holder E. Then, after compression, it is discharged from the self-priming pump.

Specific Applications of A Self-priming Pump

To operate the extreme conditions, a self-priming pump is a great choice. In different industries, this pump plays individual roles. In the chemical industries, this pump operates a mixture of air and liquid.

It also works as a draining pump to extract fluid from sealed tanks. In the food industries, it executes the concentrated process of sugar refining. In mining industries, it removes seawater.

In paper industries, a self-priming pump operates the flow of black water and white water. In the electric power-plant, it involves its potent mechanism into various water treatment.

Competent Features of a Self-priming Pump

A competent model of self-priming pump incorporates few functional features, which make it different from other regular pumps. Those are the following :

Outstanding Self-priming Mechanism

The innovative mechanism of a self-priming pump makes it accessible worldwide. So, a potent model of this pump features the comprehensive arrangement of air-water separation. And this capability can create a maximum vacuum of 6 to 9m water column. Potential vacuum creation reflects the potent power of self-priming.

Potential Air Suction

Pumping the best model of a self-priming pump separates a large amount of air from the passage. And it also discharges a large amount of water. Suppose, suction becomes a crucial matter for competent pumping, then the potent mechanism of this device keeps the fluctuation of suction conditions stable.

In these circumstances, the standard model of a self-priming pump discharges water through constant pumping. While the suction condition becomes permanent, the concentrated mechanism also restores ordinary suction conditions.

Less Dependency on NPSH

Sometimes while suction conditions fluctuate and cavitation increases, a competent model of self-priming pump keeps the pumping operation active. The changes in so many factors such as temperature, water level, suction side vacuum level can cause the suction fluctuation.

But, a reliable mechanism of a self-priming pump does not need an entry of NPSH. It applies the incredible power of self-priming and enables the equipment to stabilize the whole pumping mechanism. For having this outstanding functionality, the experts recommend this pump to extract fluid from the sealed tanks.

Broad Selection Range of Materials

Having a wide selection range of models, the mechanism of a self-priming pump reflects standard robustness. Different models of this pump feature sturdy material like SCS, FC for the best performance on diverse applications. Few models of this pump are also available with corrosion-resistant material.

Comprehensive Construction Methodology

The incredible technology of a self-priming pump emerges as standard methods for size-based equipment. For medium and large pumping devices, it features close impellers, and for the small pumping devices, it uses semi-open impellers. The impellers work as ideal blades to improve the efficiency level.

Thus, specific materials and specific equipment empower the internal mechanism of a self-priming pump. And the internationally recognized method of construction provides premium models in all sizes.

Before purchasing a self-priming pump, you can go through the recommendations available in the related videos and portals. WaterBug is such an informational portal, where you will get further topics on the reliable mechanisms of this pump.

Best of luck!


Mike Brown has done Masters in Hydrology and Water Management. He loves coffee and likes to lecture people on climate change. He plays PUBG when he is not working.

Write A Comment