In a building’s sewage discharge system, the check valve is a critical component for ensuring both safety and efficiency. A sewage lifting unit is primarily used to collect domestic or industrial wastewater generated inside the building—often containing feces, toilet paper, kitchen waste, and other debris—and pump it to the municipal pipeline. Due to the complex composition of wastewater, the absence of a check valve could allow discharged sewage to flow back into the collection tank, reducing drainage efficiency and potentially causing the pump to run in reverse, which may damage the motor.

Therefore, a reliable and durable check valve is installed at the outlet of every sewage lifting unit. This not only prevents wastewater backflow but also extends the service life of the pumping equipment.

Common Types of Sewage Check Valves

In modern sewage lifting systems, the two most commonly used check valve types are the flap check valve and the ball check valve.

1. Flap Check Valve

The flap check valve is the most widely used entry-level configuration in sewage lifting units.

• Structural Features: The flap consists of an iron core coated with rubber, with sealing achieved by the rubber pressing tightly against the valve base.

• Advantages: Simple structure, low manufacturing cost, and often made from engineering plastics, it can meet most basic sewage discharge requirements.

• Disadvantages: The sealing surface is fixed, so any debris left behind can significantly reduce sealing performance; during repeated opening and closing of the sealing plate, it is prone to water hammer impact, which can shorten its service life.

2. Ball Check Valve

The ball check valve is considered the top-performing choice in sewage treatment and is the standard configuration for high-end sewage lifting pumps (such as brands like HOMA).

• Self-cleaning Capability: Under the flow of water, the ball continuously rolls inside the valve chamber, effectively removing debris from the sealing surface during rolling to ensure long-term stable sealing performance.

• Uniform Stress Distribution: The ball’s robust structure allows for even force distribution, making it resistant to damage; even with prolonged use, wear on the ball surface is evenly distributed without compromising the seal.

• High Flow Capacity: Offers large flow passages and low resistance, making it especially suitable for sewage and industrial wastewater pipes containing suspended solids.

• Quiet Closing: Closes without causing water hammer, effectively protecting the sealing surface and extending valve lifespan.

• Excellent Durability: The ball core is usually made of a hollow iron ball coated with rubber, providing elasticity and vibration absorption, which further enhances operational stability.

• Strong Sealing Performance: Features a narrow sealing surface with high sealing pressure, maintaining excellent check valve function even in complex sewage environments.

Overall, the ball check valve not only reduces maintenance frequency but also significantly enhances the reliability and service life of sewage pumping systems. Therefore, it is the preferred choice for high-end and long-term sewage lifting projects.

Conclusion

In sewage lifting systems, the choice of check valve directly affects the operational efficiency and lifespan of the equipment. The flap check valve is suitable for cost-sensitive applications and relatively simple environments, while the ball check valve, with its excellent self-cleaning capability, strong sealing performance, and durability, has become the preferred solution for high-performance sewage systems.

Common Questions & Answers (Q&A)

Q1: Which is more suitable for sewage systems, flap check valves or ball check valves?
A: For sewage systems with high impurity content and long-term operation, ball check valves are more suitable. If the budget is limited and the sewage environment is relatively simple, flap check valves can meet the requirements.

Q2: Why are ball check valves more durable?
A: Because the ball continuously rolls evenly during operation, it self-cleans the sealing surface, and wear is evenly distributed, preventing fixed wear points and thereby extending the valve’s lifespan.

Q3: Do suspended solids in sewage affect the performance of check valves?
A: Flap check valves may be affected by suspended solids, but ball check valves have larger flow passages, lower flow resistance, and excellent self-cleaning capabilities, making them highly suitable for sewage containing suspended solids.