Pump Loses Prime When Turned off: Understanding the Causes and Solutions

A pump can lose prime when turned off due to an air leak in the suction side or a clogged impeller. This issue can cause the pump to struggle during startup, resulting in damage to the motor or a loss of efficiency.

Pumps are a vital tool for many industries, including water supply and wastewater treatment. However, these machines can encounter problems, such as losing prime when turned off. If a pump loses prime when turned off, it may struggle to start up again and cause damage to the machine. In this article, we will discuss the causes of a pump losing prime when turned off and how to solve the issue to ensure the pump’s efficiency. Understanding the causes of this problem can help operators prevent damage to the pump and avoid expensive repairs.

Pump Loses Prime When Turned off: Understanding the Causes and Solutions

Credit: empirepumpinc.com

The Importance Of Prime In Pumps

Pumps are an essential component in many industrial, commercial and household applications. They are used for conveying liquids from one place to another. The perfect functioning of a pump depends on a key factor called prime. Prime is the process of removing all the air present inside a pump and filling it with liquid before starting the pumping process.

In this section, we will discuss the importance of prime in pumps, the definition of priming, and the effects of losing prime in pumps.

Definition Of Priming

Priming is the process of removing all the air inside the pump and filling it with the liquid before starting the pumping process. Priming is necessary for the pump to function correctly. During the priming process, all the air present inside the pump and suction pipeline is evacuated.

This creates a partial vacuum inside the pump, which draws the liquid into the pump. Once the liquid fills the pump and suction pipeline, it creates a continuous flow of the liquid through the pump.

Importance Of Priming In Pumps

Prime is essential for the optimal functioning of the pump.

Primed pumps offer several advantages, including:

  • Improved performance and efficiency
  • Reduced power consumption
  • Extended life span of pump components
  • Easy operations

Primed pumps are vital in water-based applications, such as firefighting, irrigation, and municipal water supply. In such applications, an interruption in the pump’s flow can cause serious consequences like property damage and loss of lives.

Effects Of Losing Prime In Pumps

Losing prime in a pump means the air enters the pump casing while the pump is not in operation.

  • Reduced flow rate
  • Increased energy consumption
  • Damage to impellers, seals, and bearings
  • Diminished pump efficiency
  • Increased maintenance and repair costs

It is crucial to prevent losing the prime in pumps. Common causes for losing prime include leaky mechanical seals, faulty valves, worn check valves, and blocked suction lines. Therefore, proper maintenance and inspection of the pump and pipeline are necessary to prevent loss of prime and pump failure.

The prime is a crucial aspect of the pump’s optimal functioning. It ensures that pumps operate efficiently and effectively. In the absence of prime, pumps can cause considerable harm, resulting in increased repair and maintenance costs. Proper maintenance and inspection of the pump and pipeline are necessary to prevent loss of prime and pump failure.

Causes Of Pump Loss Of Prime

Pump loss of prime is a common problem encountered in pump applications. When a pump loses its prime, it can no longer perform efficiently and effectively, leading to unwanted downtime and costly repairs. In this blog post, we’ll discuss the causes of pump loss of prime and what you can do to mitigate them.

Air Leakage In Suction Lines

One of the primary causes of pump loss of prime is air leakage in suction lines. Air can enter the pump system through leaks in the suction pipe or fittings, causing the pump to lose its prime.

  • Loose or damaged suction fittings
  • Cracks or holes in suction pipes
  • Inadequate joint tightness

Vaporization Of Liquid

Another common cause of pump loss of prime is the vaporization of liquid. Pumps rely on the liquid they’re pumping to maintain their prime. When the liquid vaporizes due to high temperatures or low pressure, the pump loses prime.

  • High operating temperatures
  • Low inlet pressure
  • Inadequate npsh (net positive suction head)

Clogged Suction Strainer

Pumps also lose prime when the suction strainer becomes clogged. The strainer is responsible for filtering out solid particles in the liquid being pumped. When the strainer becomes clogged, the pump’s ability to pull liquid is compromised, leading to a loss of prime.

  • Debris in the liquid being pumped
  • Buildup of sediment in the strainer
  • Inadequate strainer maintenance

An Inadequate Level Of Liquid Stored In The Tank

Another cause of pump loss of prime is an inadequate level of liquid stored in the tank. Pumps require a certain amount of liquid to maintain their prime. When the liquid level in the tank falls below a certain point, the pump loses its prime.

  • Incorrect pump sizing
  • Inadequate tank capacity
  • Unforeseen demands on the liquid inside the tank

Mechanical Failure Or Wear And Tear Of Parts

Lastly, pumps can lose prime due to mechanical failure or wear and tear of parts. Pumps are complex machines with many moving parts that can become damaged or worn over time.

  • Worn impellers
  • Damaged seals
  • Bearing failures

By understanding the causes of pump loss of prime, you can take the necessary steps to mitigate them. Regular maintenance, including checking for any leaks, ensuring an adequate liquid level, and replacing worn or damaged parts, can help prevent pumps from losing their prime.

Why My Water Pump Loses Prime All The Time

Solutions To Pump Loss Of Prime

Possible blog post section:

Pump loss of prime: solutions to get your pumping system running effectively again

Do you experience difficulties restarting your pump after it is turned off? This problem is commonly known as pump loss of prime, which occurs when air gets into the suction line and prevents the pump from generating suction. Without suction, the pump cannot move the liquid, and your pumping system will not operate efficiently.

Inspection Of Suction Lines And Connections

The first step in resolving pump loss of prime is to inspect the suction line and its connections for any signs of damage or wear that may allow air to enter the system.

  • Check for cracks or worn-out suction hoses or pipes
  • Inspect the gaskets, nuts, and bolts that connect the suction line to the pump, as they may also loosen over time
  • Look for any debris or foreign objects that may clog the suction line and impede the flow of liquid

Fix any identified issues with the suction line and connections to ensure that they are airtight.

Check For Any Air Leaks

Air leaks can occur in various parts of the pumping system, including the suction line, pump housing, and mechanical seal.

  • Conduct a visual inspection of the system to identify any visible cracks or wear on the seals, housing, and related parts
  • Tighten any loose bolts and gaskets that may cause air leaks in the system
  • Apply a soap solution or leak detector spray to the seals and other connections and look for bubbles that indicate leaks

Once you identify air leaks, fix them by replacing any damaged parts or tightening the system’s connections.

Check The Suction Strainers

Suction strainers play a vital role in keeping debris and other contaminants from entering the pump, causing damage and blocking the flow of liquid.

Evaluate Liquid Levels In Tanks

In some cases, loss of prime may result from low liquid levels in the tank supplying the pump. Check the liquid levels in the tank and refill it to the recommended level. Regularly monitor and maintain the liquid levels in the tank to prevent pump loss of prime due to low levels.

Pump Maintenance And Part Replacement

Regular maintenance of your pump system can prevent issues such as loss of prime. Follow the manufacturer’s maintenance guidelines and replace any damaged or worn-out parts with new ones to avoid pump failure and ensure efficient operation.

Use Of Check Valves

Check valves play a critical role in preventing backflow and maintaining the pump’s prime. Ensure that you use appropriate check valves that are suited for your pump system’s specific needs. Regularly inspect and replace worn-out or damaged check valves to prevent pump loss of prime.

Pump loss of prime can be frustrating and result in significant downtime, lost productivity, and increased costs. However, you can prevent and address this issue by inspecting the suction lines and connections, checking for air leaks, inspecting and cleaning the suction strainers, evaluating liquid levels in tanks, conducting regular pump maintenance, and using check valves.

When you address these areas, your pumping system will operate efficiently, and costly downtime will be minimized.

Preventive Maintenance To Avoid Pump Loss Of Prime

Pumps are critical components in many commercial and industrial applications, making loss of prime a significant problem. It can occur when the pump is turned off, and it results in the pump losing suction. Preventive maintenance is essential to avoid such a scenario, and here, we share some maintenance tips that will help you maintain your pump effectively.

Regular Inspection

One of the best ways to prevent pump loss of prime is through regular inspection. This will ensure that you spot problems early on before they escalate.

  • Any visible signs of damage to the pump or its components
  • Unusual sounds or vibrations when the pump is in operation
  • Oil leaks or other types of fluid leaks
  • Clogged filters or strainers that could impede water flow

Check Schedules

Another effective preventive maintenance tip is to implement a regular maintenance schedule.

  • Weekly checks to ensure that your pump is in good working condition
  • Bi-annual maintenance performed by a professional service provider
  • Annual checks for worn-out parts that require replacement.

Proper Pump Use

Pumps are designed for specific purposes, so it is essential to ensure that the appropriate pump is used for a specific application. Using the wrong pump can damage it and cause loss of prime. Always refer to the manufacturer’s guidelines for optimum pump usage.

Standard Operating Procedures

Standard operating procedures ensure that your pump runs optimally and that there is less risk of loss of prime.

  • Always prime the pump before use, and never let it run dry
  • Use the recommended fluid levels and types as specified in the user manual
  • Clean and lubricate parts as required

Maintenance Tips

Maintaining your pump requires diligence and attention to detail.

  • Regularly inspect hoses and fittings for cracks, leaks, or other damage
  • Check the pump’s impeller for any signs of wear or damage
  • Keep the pump’s intake and discharge free of debris, dirt, and other materials that may cause blockages
  • Regularly test the pump’s electrical connections and ensure the wiring is in good condition.

By implementing proper maintenance procedures, you can avoid pump loss of prime and keep your pump running optimally for years to come. Remember to always refer to the manufacturer’s guidelines for optimum pump usage.

Frequently Asked Questions On Pump Loses Prime When Turned Off

What Does It Mean When A Pump Loses Its Prime?

When a pump loses its prime, it means that air has entered the system, interrupting water flow and leading to low pressure.

What Are Some Common Reasons For A Pump Losing Prime?

Some common reasons for a pump losing prime include leaks, clogs, damaged check valves, and faulty foot valves.

How Can You Prevent A Pump From Losing Its Prime?

To prevent a pump from losing its prime, regularly inspect and maintain all parts of the system, including valves, pipes, and fittings.

How Do You Fix A Pump That Has Lost Its Prime?

To fix a pump that has lost its prime, start by shutting off power to the pump and then removing any blockages or leaks. You may also need to bleed air from the system and ensure proper installation of check and foot valves.


Pump losing prime is a common issue experienced by many pump owners. However, with the right knowledge and skills, it is possible to troubleshoot and solve the problem. Remember to check the inlet conditions and ensure that there are no leaks or air leaks around the pump.

In addition, ensure that the pump is properly installed and that the impeller is in good working condition. If you encounter any difficulties in solving the problem, do not hesitate to seek the help of a professional pump expert. Overall, regular maintenance and timely inspections go a long way in preventing pump malfunction and prolonging its lifespan.

By taking good care of your pump, you can save yourself time, money, and the hassle of repairing or replacing it. Let us know your thoughts or suggestions on how to avoid pump losing prime in the comments section below.

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