Case Studies

Pumps are only as good as they are efficient. Various issues can lead to inefficiencies. It’s important to identify and resolve issues quickly so your pumps can get back to work.

Allied Pumps is sharing some best practices on how to self-identify and correct pumping problems.

Common symptoms and what may be causing them

Abnormal flow

If the flow is abnormal, this is a definite sign of a problem. Is the decrease visible? Is the pump taking more time to do the same job? Its sluggish operation may be due to a collapsed suction hose lining. Other root causes could be a leaking gasket, a plugged suction line, or a damaged impeller or wear plate.

To pinpoint the culprit, measure the discharge pressure and suction vacuum. Compare, if available, to the initial readings taken at installation. Look for any high abnormal readings. A higher than normal discharge could indicate a clogged discharge line, a closed valve or an obstruction. It is good practice to install gauges approximately two to four pipe diameters from the pump.

Noisy pumps

The most common noise is that of that of rocks in a can. This could indicate cavitation, which may be due to a suction lift being too high, a too long suction hose, plugged or collapsed lining, a blocked strainer or some combination of all of these.

Failing bearings can also cause extreme noise. When considering a noise, categorize it as mechanical or hydraulic. Run the pump for a few moments without water. If the noise is gone, it’s mechanical. Gauge reading will direct you the problem side of the system if it’s a hydraulic noise.

Frequent clogging

If a pump’s suction check valve is clogged, the strainer may be the wrong size or the face clearance could be too wide. The strainer may be stuck in mud, plugging the suction side.

Overheating

This is almost always the result of restriction of the flow of liquid into or out of the pump. It could also be improper impeller clearance which may be slowing re-priming. There could be other issues related to circulation. If the pump is hot, do not open. Wait until it cools.

Air Leaks

To check for air leaks, use a vacuum gauge to test the suction line, fittings and pipe plugs seal. It should be airtight. Use pipe dope to seal gauge threads and pipe plugs.

If a vacuum gauge falls off after shutdown, atmospheric pressure is entering the suction pipe causing the pump to lose its static lift.

Fix this by replacing the suction flap valve if worn. Check for air leaks if the product returns to the sump. Replace leaky seals and badly worn hoses, if necessary.

PUMP PROBLEM CHECKLIST

The problem may be due to issues with the pump. You’ll need to investigate these areas.

• Check the volute casing, impeller vanes, wear plate or wear rings and attaching hardware. Complete a shut-off test to determine internal wear. Start the pump, and at full flow, close a discharge valve. Record the suction and discharge readings.
• Check the impeller clearance. If the clearance is off, components can wear due to rubbing.
• Check the seal. Sand or other materials can break the seal. If the integrity is compromised then replace the seal.
• Check the bearings. Worn bearings cause a wobble. This leads to noise and overheating. It could eventually freeze so check and replace.
• Check the engine or motor. Is the motor receiving enough power? This can be a serious issue and should be rectified with service or maintenance.
• Check air release devices, valves, check valves and shock control devices for proper operation. Older lines could be rusted. This can lead to friction and reduced flow. Replace lines that show signs of deterioration.

Efficient pump operation is critical to your system. Regular maintenance and tests will keep pumps running longer.

If you have any questions about pump issues, feel free to contact us.