Centrifugal pumps, are among the most versatile and used in many industries to move fluids. If they suddenly fail, you don’t need us to inform you how seriously the production process can be affected.

While it’s easy to continue operations despite little glitches in pump performance—after all, demand and pressure to speed up production can be high—monitor your water pumps closely and pay attention to any indications of problems. Common problems you may encounter can lead to pump failure if left unattended. So, what is the most common problem of centrifugal pumps?

Signs that Your Centrifugal Pump is About to Fail

Your Pump Won’t Start

OK, so this sign is pretty obvious. An electrical fault may be the cause. Check first for any disconnected or loose wiring. A circuit breaker or blown fuse is also an easy fix. However, a failed motor might necessitate replacement.

Failure to start might indicate a physical blockage if the fault is not electrical. The pump must be stripped to remove anything lodged in the impeller preventing it from rotating.

Reduced Fluid Flow

Several conditions can cause reduced flow through the centrifugal pump:

Wrong impeller rotation. This happens if the motor is wired improperly and the rotation of the impeller is reversed. If the impeller backs off the shaft, this can seriously damage the pump components.

Clogged suction, discharge line, or impeller. Any debris clogging the pump inlet or discharge must be cleared out, and the pump should be stripped to take debris off the impeller.

Worn impeller, wear plate, or wear ring. The pump’s hydraulic capacity is reduced if any of these internal components are worn. Component wear makes clearances open up, leading to greater fluid circulation inside the pump and reduced flow.

Sometimes, the problem might be easy to fix when caused by something more obvious, such as an open bypass valve.  However, worn impellers and other parts require repair or replacement.

Leaking

Any leakage from the pump, however small, spells trouble. Excessive or abnormal temperature, pressure, or corrosion can loosen the mechanical joints and seals.

Pump repairs may involve tightening any loose fasteners around the joint. In other instances, gaskets may need to be replaced. The mechanical seal must be replaced if the pump leaks at the shaft.

Rumbling or Rattling Noises

These noises in centrifugal pumps are often accompanied by vibration and are most frequently a sign of cavitation. Cavitation causes intense shockwaves inside the pump, significantly damaging the impeller and pump housing.

Any sign of cavitation should be addressed immediately to prevent substantial damage to the pump. Excessive vibration will result in premature failure of the mechanical seal and bearings.

What Is the Most Common Problem of Centrifugal Pumps?

One of the most common problems with centrifugal pumps is a reduced or lower-than-expected liquid flow. Low flow means more downtime for the crew, costing money and putting deadlines at risk. Low water flow is often less about your water pump and has more to do with the situation. Below are a few things to review to troubleshoot centrifugal pump issues involving low water flow.

1. Pump Too Far From The Liquid Source

The greater the distance a pump pulls the water, the lower the flow rate. If you move too far away from the liquid source, then more energy is used for ‘sucking’ the liquid and less for releasing, which slows down the flow rate. Typically, pumps should be within 20 feet of the liquid source. Depending on the typography and how high the pump is relative to the liquid, the flow may be reduced at even shorter distances. Your pump has individual specifications, so be sure you read the specs and operate within them.

2. Level of water

There are no limits to how far down you can draw the water in a bore, given that, by definition, a submersible pump is designed to be submerged in water. However, there is a certain point at which the pump’s performance is affected, and the pump itself becomes damaged.

If your pump stops and starts frequently due to low water levels, it may reduce its lifespan and damage it. Knowing the maximum number of times your pump should be started daily based on its diameter is crucial for preventing motor failure. Another thing that can help is monitoring the incoming power supply since a reduced voltage supply results in an increased amperage draw, which will mean a higher operating temperature.

3. Reduction In Supply Line Diameter

Your pump is designed to operate with a certain diameter input line. In some cases, we have seen people attach a smaller than recommended hose or line (using reduction couplings). Depending on the intake line you use, it is also possible that the line crimps or is “sucked in” on itself.

There are a few things to check. The intake line should be the recommended size and at least the same size as the discharge line. Walk the intake line from the source to the pump and ensure no kinks. Use a rigid intake line, sometimes called a non-collapsible hose, if possible.

4. Intake Line Obstruction

Anything that impedes the water’s flow into the line will cause a reduction in the flow rate. Debris blockage is a common problem with murky water; it can be hard to see the intake hose. However, operators should check to ensure no debris is blocking the intake. The blockage usually happens at the filter as it does its job to prevent damage to the water pump. Remove the debris and reposition the hose to start pumping again.

The intake filter or screen can be the culprit, even without debris. While you must ensure the filter is fine enough to prevent damaging solids from entering the pump, too fine a filter for the water pump will restrict the flow right as the water enters the intake. Be sure the filter is proper for the pump.

5. Unchecked changes in pumping conditions

A well-maintained pump will typically give many years of good service; however, should the pump application change, it will almost certainly result in an altered pumping condition. This may cause the pump to try and operate at a less-than-optimal point and could result in reduced flow, pressure changes, and often complete failure. If a bore pump operator is not using a pressure gauge, changes like these can often go unnoticed until significant deterioration has occurred.

Setting up a pressure gauge for your pump can be very useful when determining if a change in the application has occurred. Monitoring your bore pump’s power supply, flow, and operational elements can make a big difference when troubleshooting problems.

6. Iron Contamination

Iron oxidation and iron bacteria are two main factors damaging water pumps. These contaminants clog and corrode the pump’s parts when they accumulate, eventually leading to complete system failure. If you see red-tinted sludge or threads in your pump system, it is likely a sign of iron contamination.

So, cleaning and disinfecting the system is an effective method for getting rid of iron bacteria, and using a liquid solution can help flush out any buildups of iron deposits. In addition, an in-line filter can assist with capturing and constraining these impurities.

7. Improperly Connected Motor

Water pumps like centrifugal pumps are made to operate with the impeller going in one direction. The pump will not operate properly if it goes in the opposite direction. This can occur if the electrical connections to the electric motor must be established correctly. Review the electric motor setup and user instructions to ensure correct connections.

Low flow is an issue whether you are dewatering a job site, irrigating a field, or applying your water pump for any other purpose. In some cases, like a firefighting pump, it can be a life-or-death matter. One way to minimize onsite issues is to regularly check all your equipment, replace worn parts, and perform maintenance as needed. But when confronted with low flow rates, follow the above steps, and you’ll be able to get your water pump back in action and your crew back to work.

8. Motor failure

The most common reason for pump failure is motor failure. This happens when the motor itself overheats, most commonly due to inadequate cooling from the water passing the exterior of the motor. To be balanced and sustainable, a pump output delivery needs to match the groundwater inflow. If the minimum velocity level for adequate cooling (0.15m/s) does not occur, then the motor will overheat and fail.

If you have low-level flow protection and notice your unit frequently starting and stopping, this could be due to reduced groundwater inflow. It is well worth investigating to prevent a motor failure.

Do you want to learn more about the most common problems affecting centrifugal pumps? Please reach out to us today!