When selecting the right plumbing valve for your project, there are many types of valves to choose from. Two commonly used valves are a check valve and a non-return valve. Although they may seem similar, these valves have distinct differences. In this blog post, we’ll discuss the differences between check valves and non-return valves to help you make an informed decision.
Difference Between Check Valve and Non Return Valve
Structure
The primary difference between check and non-return valves is their structure. A check valve has a disc or ball that allows flow in one direction only. If the fluid flow tries to reverse, the disc or ball seals against the valve seat, preventing the backflow. A non-return valve, alternatively, employs a stopper to prevent backflow. It’s a mechanical valve that allows flow in one direction and closes if the flow tries to travel in the opposite direction.
Applications
Check valves and find their use in systems that require prevention of backflow of unwanted fluid, like wastewater or sewage. They are employed in water heating systems, chemical process handling, oil drilling, and many other industries. Non-return valves, on the other hand, have more widespread use. They are installed in systems requiring fluid flow only in one direction, such as irrigation, pumping, and hydraulics.
Working Mechanism
Check valves work using the ‘pressure drop’ principle, which relies on the pressure differential created by the fluid. When the valve is opened, the forward pressure from the fluid lifts the valve disc or ball, creating a passage for the fluid. When fluid flow stops and pressure reduces, the valve disc or ball closes, preventing backflow. Non-return valves, alternatively, work on the principle of weight or gravity. The stopper in a non-return valve is designed to close the valve using its weight when the fluid tries to flow back.
Maintenance
Check valves have relatively low maintenance compared to non-return valves. They are designed to last long because they’re constructed with tough materials like PVC, cast iron, or stainless steel. The valve’s ball or disc also does not experience friction while functioning, making it less prone to wear and tear. Non-return valves need more attention because their weight and gravity-driven mechanisms need regular inspection and servicing.
Design
The installation of non-return valves is a top priority in complex hydraulic systems. The non-return valves have a simple design that can be modified according to the weight and fluid pressure. Each non-return valve is designed in such a way that it exhibits minimum resistance to the fluid flow. In contrast, check valves have a limited design due to the ball or disc mechanism, which allows only a specific fluid pressure range.
Conclusion:
In conclusion, check and non-return valves serve similar yet distinct functions in plumbing systems. A check valve prevents backflow, while a non-return valve prevents flow in the reverse direction. The decision between the two valves depends on the intended use case and other relevant factors like fluid pressure, flow rate, etc. Understanding these differences will help you choose the right valve based on your plumbing requirements.
