Dual Plate Check Valve Factory

Check Valves in Sewage Pumping Systems: A Guide for People Who Manage Facilities

If you go to a lift station you will see that the people who do maintenance have strong feelings about check valves. Some people really like swing check valves. Other people have taken them all out. If you ask them why they feel this way they will tell you stories about getting called to work at 2 in the morning or about water hammer that was so strong it broke pipes or about check valves that got stuck open because something like a rag got in the way. This guide is about the life experiences of choosing, installing and taking care of check valves based on what actually happens in the field not just what the specifications say.

What Is a Check Valve for a Sewage Pump?

A check valve allows flow in one direction and prevents it from flowing back. No handles, no actuators. It responds entirely to what the pump does.

During a pump cycle:

• Pump starts: pressure pushes the internal disc or flapper open
• Pump stops: pressure drops, and the valve closes by spring force, gravity, or backflow pressure

Why every discharge line needs one:

Skip it, and trouble follows. When the pump cuts off, the water column falls back down. This causes:

• Backspin that loosens impeller nuts and strains the motor
• Pipe drainage, forcing the pump to refill from scratch every cycle
• Pressure surges that crack pipes and fittings
• Wasted energy moving the same water repeatedly

Common sewage valve types:

Can a Check Valve Be Installed Vertically?

Yes, but only with certain designs. Getting this wrong means the valve never closes properly.

What works vertically:

The right way to do vertical:

Flow must move upward—inlet at bottom, outlet on top. This lets gravity assist the spring, and sediment falls through rather than packing onto the seat.

Before bolting it in:

• Check the flow arrow points up
• Leave straight pipe upstream to smooth turbulence
• Match spring tension to system pressure; too strong and the valve never opens fully, too weak and it flutters

What Are the Main Advantages of Dual Plate Check Valves?

Dual plate valves have become the default choice for new lift stations. Here is why.

Surge control:

A swing check can take half a second to close. That gives reverse flow time to accelerate, and the pressure spike can hit 20 bar in larger pipes. Dual plates close much faster—short disc travel with spring assist. Surge usually stays under 2 bar.

Weight and handling:

A 10-inch dual plate weighs about 25 kg. The equivalent swing check is around 180 kg. That difference matters in cramped stations with no overhead crane.

Cost:

Less metal means lower purchase price, cheaper freight, and easier storage.

Where dual plates struggle:

• Rags and stringy debris can wrap around spring pins
• Thick sludge may prevent full disc opening
• Very low flow causes fluttering instead of full open

Do Spring-Loaded Check Valves Require Regular Maintenance?

Yes. Springs lose tension, seats wear, and debris finds its way into every moving part.

A practical schedule:

• Visual check at least once a year
• Torque flange bolts twice a year—vibration works them loose
• Look for weeping around the body with pump off and backpressure on the line

Common failures:

Safety rule:

Before opening any valve, shut down the pump, close the isolation valve downstream, and bleed pressure. Sewage piping holds surprising pressure even when off.

What Are Common Check Valve Problems?

Slamming:

Loud thump every time the pump stops. Over time, shock loosens supports and cracks bodies. Fix: swap to fast-closing dual plates or adjust VFD to slow the pump before stopping.

Fluttering:

Rapid tapping sound. Valve never reaches full open because flow is too low. Fix: properly size the valve for actual operating flow, not peak pipe capacity.

Failing to close:

Flow continues backward after pump stops. Debris is usually holding the disc open. Pull and clean. If repeated, switch to rubber flapper with fewer places for debris to catch.

Failing to open:

Pump runs but flow is weak. Broken spring or heavy sludge jamming the mechanism. Cycle the pump a few times; if that fails, pull for service.

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