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One of the stations at Mount Horeb wastewater treatment plant in Wisconsin, US, had a clogged pipe that was threatening to spill raw sewage in to people’s homes.

The problem was caused by a cushion swing check valve at a lift station that kept slamming and clogging.

The particular check valves were allowing sewage to build up on top of the disc, restricting the effectiveness of the valve and causing it to slam.

Sewage would build up on the disc, pushing it further down in to the flow and creating head loss, clogging and constant slamming.

The cushion swing check valves used had a non-metallic insert for the seal.

Every time a piece of plastic, wood or any other solid would tap or chip the cork, the seal would begin to weep.

The wastewater treatment plant processes 600 gallons per day and they could not afford to have the valves out of commission.

To solve the problem, the manufacturer of the cushion swing check valves suggested that the valve should be removed from the line, shipped back to them to be repaired and then shipped back to the customer to be reinstalled.

This could have lead to downtime of over a month as the station would have been left with only one pump at the lift station and no back-up cover if pump failure was encountered.

Instead of waiting, the plant staff repaired the valves on their own in an attempt to decrease downtime.

This involved completely removing the valve from the line, removing the shaft, repairing it then reassembling it, which took four hours.

Deciding it was time for a change, the staff found out about the Valmatic Swing Flex Check Valve, which was specifically designed to combat the problem they were facing with their cushion swing check valves.

The contour of the Swing Flex’s body allows 100 per cent flow area to minimise head loss.

The Swing Flex’s disc design and domed access port allows the flow of sewage to self-flush any potential clogs before they form.

As the disc is the only moving part, there are no internal components to get in the way.

According to plant staff, the Valmatics Swing Flex Check Valve was easy to install.

It is designed with an angled seat that causes a 35deg disc stroke, less than half of a traditional weight and lever check valve.

The valve has short disc stroke and memory flex action to reduce closing time of the valve and minimise the flow reversal to prevent any water hammer.

The staff at the plant stated that once the valve was closed from the force main they could not hear a sound from the valve, not even when it was shutting.

Following the success of the Valmatic Swing Flex Check Valve on one of the two pump lines in the lift station, the plant decided to replace the remaining cushion swing check valve with the Valmatic Swing Flex Check Valve.

It took less than one hour to remove the previous valve, install the Valmatic Swing Flex Check Valve and test it for flange tightness.

MGA Controls

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