What is Priming in Pump? How Priming is done?

What is Priming in Pump?

Priming is the process of filling a pump's suction line and casing with fluid in order to create the necessary suction to start the pumping process. Priming is done to ensure that the pump is able to function properly and efficiently. Here are some reasons why priming is important:

1. Remove Air: The presence of air in the pump's suction line can cause cavitation, which can damage the pump and reduce its efficiency. Priming ensures that the suction line is filled with fluid, eliminating any air pockets.
2. Increase Efficiency: Priming the pump helps to reduce the amount of work that the pump needs to do to start moving fluid. This can improve the pump's efficiency and reduce energy costs.
3. Improve Performance: A properly primed pump will operate at its maximum performance level, providing the necessary flow rate and pressure to meet the system requirements.
4. Prevent Damage: Starting a pump without priming can cause damage to the impeller or other components, leading to costly repairs or replacements.

Priming is typically done before starting the pump or after the pump has been shut down for an extended period of time. The priming process involves filling the pump's suction line and casing with fluid and ensuring that there are no air pockets or leaks. Some pumps have automatic priming systems that can make the process easier and more efficient.

How Priming is done?

The specific process for priming a pump may vary depending on the type of pump and the specific application, but here is a general step-by-step process for priming a centrifugal pump:

Fig. 1: Centrifugal Pump

1. Check the pump: Before starting the priming process, ensure that the pump is in good working condition, with no visible damage or leaks.
2. Close discharge valve: Ensure that the pump's discharge valve is closed to prevent fluid from escaping during the priming process.
3. Fill suction line: Fill the pump's suction line with the fluid to be pumped, either by opening a valve or using a separate filling device. The fluid should be filled until the suction line and pump casing are completely filled, and no air pockets remain.
4. Vent air: Open the air vent valve located at the top of the pump casing to allow any remaining air to escape. This may take a few minutes as the air is pushed out by the fluid.
5. Close air vent: Once all air has been removed from the pump casing, close the air vent valve.
6. Open discharge valve: With the suction line and casing filled with fluid and all air removed, slowly open the pump's discharge valve.
7. Start the pump: Turn on the pump and monitor the flow and pressure to ensure that the pump is operating correctly. If the flow or pressure is not at the desired level, adjust the pump speed or discharge valve as necessary.
8. Monitor the pump: Once the pump is running, monitor it for any unusual noises, vibrations, or leaks. If any issues are detected, shut down the pump and address the issue before restarting.