Flap valve hdpe pressure line mount



Read More: "Introduction To HDPE Flap Valves"


Flap Valves WA-PWK models are HDPE material units, with 316L stainless hardware for any metallic requirement.

HDPE is resistant to most chemicals and is not subject to corrosion.


Flap Valves for pump pressure lines are used when large volumes of storm water need to be pumped out of containment structures. Flap valves prevent back flow through the pipe into the discharge lines.

WA-PWK Flap Valves are installed at pressure piping outfalls. Opening to allow pumping outflows and closing on pump shutdown to prevent flood water back flows.

WA-PWK flap valve units are equipped with venting valves for pump stop and run operations. The vent protects the flap door from drain back pressures.

Flap Valve Pump outfall Sketch drawing

PDF data pressure pipe outfall


Request email quote or call Westatlantic 1-902 455-4455

Pump Operating



The function of the air vent is not obvious during the time the pump is in operation. It only becomes clear when the pump stops.  


Pump Stops



As the pump stops, the flow reverses. In the very short time span between the pump stopping and the flap valve closing, the flow returning into the pipe can result in high pressures.


The vent prevents a vacuum formation by allowing air to enter the pipe through the air vent. As a result the valve closes slowly and in a controlled manner.

Pump Starts to Operate


When the pump starts up it compresses the air remaining in the pipe.

The compressed air leaves the pipe through the air vent.

The size of the vent pipe is approximately 10% to 15% of the flap valve bore.


Small flap valves up to 400 mm diameter are equipped with a threaded opening.

With larger diameters pipes the air vent will be equipped with a flange connection.

Contact us: Westatlantic Tech Corp, 902 455 4455

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