Troubleshooting a Sewer Bypass Startup

When startup fails, check these four common culprits before you check anything else.

You’ve done all the necessary planning for your sewer bypass and checked and rechecked every component as you installed it — and now the system won’t start.

“In spite of best efforts, there are times when some issues can arise,” said Neil Ripley, Region Product Development Manager at United Rentals.

Ripley recommends looking at these four potential trouble spots to eliminate the most common culprits.

Volute drain valve open/priming system valve closed

There’s a lot of sophisticated planning that goes into the automatic priming system on a centrifugal pump, but when something goes wrong, the culprit may be simple: Someone left the drain valve open or the priming system valve closed.

“This is the first question we ask when we get a call about priming issues. If there’s one thing I’ve noticed throughout my career, it’s that valves have a way of magically opening or closing themselves,” said Ripley.

A gasket leak or faulty suction hose/pipe

Look for the easy fixes first. The answer could be as simples as a $5 gasket that’s cut or missing inside the suction hose.

“Do a quick check to make sure all gaskets are present and in good condition,” Ripley advised. “Also, look for any physical damage such as holes or creases. Everything might have been good on installation but something may have happened as it sat during the night before startup.”

A faulty or obstructed check valve

If the check valve is open just a little bit, there is potential for an air leak. The check valve is a hard rubber flapper that has a lip seal around its circumference, and over time it can wear out. If check valves do not make a positive seal, you will have an air leak.

“If you get to this point in your troubleshooting, inspect the valve and if it appears good, apply a thick coat of a petroleum jelly around the lip seal of the flapper. Push it down firmly to seat it and try the startup again,” Ripley suggested.

The suction lift exceeds maximum limit

“The suction lift can be tricky and depends on several factors,” said Ripley . If you are working out of a manhole or wetwell, vault or other structure that is deeper than 28 feet, make sure you measure the vertical distance between the level of the water and the centerline of the pump.

Water levels fluctuate in sewer systems, and if the depth is greater than 28 feet, the pump will not prime. It’s possible the water level increased just when you were trying to start up your system. If you’re using a trailer-mounted pump, there’s a quick remedy that might make the difference: Remove the wheels, which gets the pump lower to the ground.

Planning and execution of a sewer bypass can be a large and costly undertaking and you should always consult with an expert regarding the specific circumstances, applicable rules and regulations related to your site and to your situation.

To learn more about United Rentals sewer bypass solutions, contact the United Rentals Fluid Solutions Group.

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