How to Prime an Industrial Pump

Posted: 7/3/2014

Priming industrial pumps is essential to using your pump for its intended applications and to maintain the equipment. Priming is the process of removing air from the pump and suction line to permit atmospheric pressure and flooding pressure to cause liquid to flow into the pump. Without priming, pumps will cease to function and break down.
There are several classifications of industrial pumps on the market that have their own priming procedures. Here, we will explain the best practices for priming each pumping system so you can maintain the integrity and safety of your equipment.

1. A March centrifugal pump with flooded suction.

Centrifugal pumps work on the scientific principle of centrifugal force, where water is propelled through a mechanism. The system is a pump with an impeller attached to a rotating column inside a shaft. These are connected to both an intake and discharge connection. The impeller creates pressure in the liquid inside the shaft, "throwing" the water from the impeller out through the discharge.

A flooded suction in a centrifugal pump is where liquid originates. The liquid is held at a level above the suction port of the pump, and allows liquid to arrive at the pump through gravity. Below is an example:

1) Centrifugal- Pump -with –Flooded- Suction

In order to operate this pump, liquid must already be within the flooded suction. If liquid is present at the acceptable levels, the pump is primed and ready for use.
If there is air in the system, the pump may suffer from air lock and liquid (either partially or totally) will not leave the pump.


To remove air from the system, install a bleeder valve, or a coupling may be opened on the discharge side to the atmosphere to air to escape. Below is an example of a bleeder valve:

2) Centrifugal -Pump -Bleeder-Valve-March-Pumps 

Liquid should already be in the pump when the coupling is opened. If the liquid is corrosive or and dangerous, great care should be taken when opening the coupling to not have any liquid contact the operator. It is normal to have a little liquid leave the coupling when opened.

2. A centrifugal pump without flooded suction.

This type of pump priming requires that the suction line between the tank and the pump be filled with liquid.

In order to accomplish this, the suction pipe in the tank must be below the liquid in the tank. There must be a check valve as close to the start of the suction pipe in the tank as possible. After the pump is used, unless the tank is emptied, there should be liquid in the suction pipeline. Often the suction pipe is filled by using a t connection. Below are examples of correct and incorrect mechanisms.

3) Proper-Centrifugal-Pump Installation-March-Pumps


3. A centrifugal pump with a priming reservoir chamber without flooded suction.

To properly prime this pump, the priming reservoir, placed in front of the pump, should be filled before each use. For the 750 priming chamber, the pump should be no more than 10 feet away the source of the liquid. Other priming reservoir chambers may be placed further away. Always be sure to check with the manufacturer.

The chamber should be checked after every use to ensure it is full of liquid, as the liquid may back siphon out of the chamber. A check valve can be installed to help monitor. This may also increase your friction losses. If it is not, there is a cap on top of the chamber which can be taken off and liquid can be poured in that opening.

4) Self-priming-Reservoir -750-System –March- Pumps

4. A self-priming centrifugal pump without flooded suction.

In order to prime this pump, the priming chamber should be filled by unscrewing the cap on top.

5) Self-priming-centrifugal-pump –No-Flooded-Suction –March-Pumps

The self-priming 7 should be used no more than 12 feet away from the source of the liquid. Normally, the liquid does not back siphon out from the chamber. However, it is still encouraged to check the chamber to ensure it is filled with capacity before each use.

If it is not filled completely, the pump may not be able to suck up any more liquid, and then is dependent on the distance away from the source of liquid.

By following these instructions and staying within the manufacturer's specs, you can expect to have a longer lifetime from your pump equipment. If you have any other concerns, be sure to contact us right away. We're happy to help!

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