Suction is an innovative process, through which a limited amount of vacuum appears in a specific part of the devices. This process works on the theory of air removal to send water into the vacant space.

In general terms, a suction pump is a potential device to execute the dewatering process. This device uses atmospheric pressure as the primary driving force. The whole mechanism runs by lifting the piston to create a partial vacuum.

As an external force, environmental pressure pushes water to the internal cylinder of the suction pump. And the internal mechanism moves out the water with the aid of an outlet valve. Here, while running a suction device, the environmental pressure can push water to the maximum level.

Working Principle of Suction Pump

Every pumping device has a specific mechanism. And a suction pump also has a concentrated tool to create the phase of total air removal. This pumping device picks liquids and water involving suction mechanisms. It consists of an essential cylinder with a vertical surface. A piston is another significant equipment of a suction pump. The piston acts in up and down mode.

While vacuum appears in the specific part of the suction portion, the atmospheric air comes immediately to fill it. Both pumping devices and cylinders contain valves as a controlling unit to regulate the water flow.

Considerable Facts of Suction Lift For Smooth Pumping

The competent mechanism of the suction pump depends on some factors. Among these factors, the role of suction lift is a potential matter for a smooth dewatering process.

So, during the selection of a dewatering pump, users should consider specific suction lift for the applications. The following points will help to go through the essential facts on the suction lift:

❏ The concentrated mechanism of a suction pump makes the entry of water following the core suction theory. In this process, to make the water’s entrance, the atmospheric air overcomes a vertical distance. This vertical distance defines the suction lift.

❏ The suction lift span holds the space from the maximum height of the pumping fluid to the suction pump casing. The casing portion is equipped at the point of the impeller.

❏ According to physics theory, the surrounding pressure leads the pump to raise water to a fixed height. For a suction pump, this fixed height can reach up to 28 ft in the ideal conditions. This theory confirms that suction mechanisms can not pick the water more than this maximum height range.

❏ As a user, you should keep in mind some precautions to select the competent models of the suction pump. Because, in diverse applications, the pumping device has to deal with a high range of suction lifts. While you are using a self-priming pump with a centrifugal mechanism and an end-suction pump with a centrifugal feature, you will get a safe platform. This platform enhances the mechanism with proximity to the water for reducing suction lift. This functionality is termed as ‘benching down.’

❏ In cases of submersible pumps, the end part of the pump is submerged in the pumping fluid. So, experts eliminate the safety issue of suction lift for this suction pump. But they also recommend efficient horsepower based models to overcome the vertical distance of the discharged fluid.

❏ As a user, to maintain the suction lift safely, you must keep in mind the matter of altitude. In Florida, where the sea level and elevation level exist nearby, the suction lift can low. And in Denver, with higher elevation, the applications can differ from the recommended level of suction lift.

Role of NPSH For Flawless Operation of Suction Pump?

Having competent equipment is a good thing for getting the best performance. But still, so many pump users face lots of struggle to operate pumps. For those, here we are explaining the relation of NPSH with a suction pump. As per general rule, water flows from high-level pressure areas to the low-level pressure area.

The equipment of a pump uses this theory to activate the inlet operation. This part allows the entry of water for being forced by the head pressure into the internal passage of the pump.

During the placement of the pump, the user should select the top place of the mercury barometer. Even after ideal vacuum creation, at the inlet, environmental pressure regulates the lift height of water. Users can get a hint about it from the mercury barometer.

If the water weight becomes lighter than mercury, then the height of the lift can increase. But still, the external pressure of a suction pump can limit the range of operation.

And this limit depends on the critical factors of Net Positive Suction Head (NPSH). It is defined as two segments:

NPSH Available (NPSHA) – The independent range of pressure at the suction point in the pump.
NPSH Required (NPSHR) – The minimum level of required pressure at the pump’s suction point to maintain the pump’s capacity.

NPSHA is a functional feature of a suction pump and needs to be calculated for smooth operation. NPSHR is an optimum level of the functional elements of a pump, provided by a manufacturer.

Here, the users should always keep in mind that NPSHA needs to be higher than NPSHR. This calculation helps the users to operate the suction pump without a chance of cavitating.

So, the users are responsible for finding potential ways to maintain more suction-based pressure availability at higher ranges than the suction pump requirement.

All the points, which have been discussed on NPSH factors are very crucial for smooth operation. The margin between two types of Net Positive Suction Head ensures the safe performance of a suction pump.

But, many users overlook this margin during pump selection; it becomes fatal. If this margin changes or disappears, bubbles form at the inlet of the pump. And this hints severe cavitation, which leads to a sudden collapse of the pumping system. This collapse is as dangerous as permanent damage.

So, the pump operators have to maintain the positive value on the NPSH margin to prevent cavitation. The potential pump engineering follows NPSH factors to provide damage-free performances.

And if the users select the suction pump models and the required margin, they get the best returns even in specific conditions.

The competent mechanism of a suction pump depends on several important factors. So, buying the potent model of this pump is not an easy task.

WaterBug is such a portal, which discusses plenty of suction pump relevant factors. You can join this website to get the latest update of extensive pumping mechanisms.


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.

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