What Does Priming A Pump Mean

By Bella Sungkawa | Published: | Engineering | 2 min read

Short Answer

Priming a pump is the procedure of removing air from the pump and its suction line and filling it with liquid so that the pump can create the necessary suction to move fluid. It is essential for many types of pumps, especially those that are not self‑priming, and is commonly performed in plumbing, irrigation, and industrial applications.

Complete Explanation

Priming a pump refers to the process of eliminating air from the pump housing and suction line and replacing it with the liquid that the pump is intended to move. By filling these spaces with fluid, the pump can generate the required vacuum to draw additional liquid into the system. Without proper priming, many pumps cannot develop sufficient suction, leading to loss of performance, overheating, or damage such as cavitation.

  • Definition:
    Priming is the act of filling a pump’s inlet and internal cavities with liquid to enable normal operation.
  • Purpose:
    It removes air pockets that would otherwise prevent the pump from creating adequate suction.
  • Typical Methods:
    Manual filling, using a priming bulb or hand pump, employing a self‑priming pump design, or installing a foot valve to retain liquid in the suction line.
  • Applicable Pump Types:
    Non‑self‑priming centrifugal pumps, positive‑displacement pumps, and some axial‑flow pumps require priming, whereas many self‑priming centrifugal pumps are designed to draw in air‑filled suction lines automatically.
  • Importance in Operation:
    Proper priming prevents cavitation, reduces wear, improves efficiency, and extends the service life of the pump.

Common Misconceptions

Myth

Priming is only necessary when a pump is first installed.

Fact

Pumps may lose their prime after shutdown, air intrusion, or leakage and must be re‑primed before restarting.

Myth

All pumps can self‑prime without user intervention.

Fact

Only pumps specifically designed as self‑priming can operate with air in the suction line; most centrifugal pumps require manual priming.

FAQ

Why can't a non‑self‑priming pump start with air in the suction line?

Non‑self‑priming pumps rely on the presence of liquid at the inlet to generate the necessary pressure differential. Air compresses easily, preventing the pump from building the vacuum needed to draw fluid.

How often should a pump be primed?

A pump should be primed whenever it is shut down for a period that allows air to enter the suction line, after maintenance, or if a loss of prime is suspected due to reduced flow or unusual noises.

Can a foot valve eliminate the need for manual priming?

A foot valve can retain liquid in the suction line when the pump stops, reducing the frequency of manual priming, but it does not replace priming if air has entered the system.

References

  1. Murray, D. G. (2010). *Hydraulic Machinery and Systems*. McGraw‑Hill.
  2. American Petroleum Institute. (2021). *API Standard 610 – Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries*.
  3. Cameron, J. (2015). *Pump Handbook* (4th ed.). Elsevier.
  4. U.S. Environmental Protection Agency. (2019). *Water Treatment Technology Manual*.
  5. Miller, R. W. (2018). *Principles of Fluid Mechanics* (7th ed.). Wiley.

Related Terms

Pump Cavitation
The formation of vapor bubbles in a liquid near a pump impeller due to low pressure, which can cause damage when the bubbles collapse.
Suction Lift
The vertical distance a pump must lift liquid from the source to the pump inlet, influencing priming requirements.
Check Valve
A valve that allows fluid flow in one direction, often used to retain liquid in the suction line and aid priming.

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