Valves play very crucial roles in mechanical engineering. The various types of valves available serve a similar purpose but each have their own operating mechanism. A valve is a device that controls the flow of liquids, gases, and slurries. This control is achieved by a moveable element that restricts, partially obstructs, or opens a passageway using the valve.
This post will discuss the difference between two return valves of interest: a check valve and a non-return valve. These are two vital valves that are frequently utilized in some highly important applications.
A non-return valve allows liquids to flow in just one direction. As the name implies, the primary function of a non-return valve is to keep the fluid flow in just one order. When the fluid in the line reverses direction and begins to flow back the way it came, a check valve stops or prevents the backflow by allowing flow in one direction. Check valves are generally intended for use in high-pressure situations.
Understanding Check Valves
Check valves are ubiquitous in their applications in that they are found in almost every industrial application, where they act as one-way or non-return valves. Check valves are designed to be simple devices. They aid in the execution of an important role in fluid control. Check valves prevent reversal flows, resulting in less damage and more efficient operations.
The phenomenon can result in a water hammer when reverse water flow occurs. High-pressure surges often follow this phenomenon in pipework, valves, and pumps. It could cause significant damage or rupture of the system, as well as the piping. The system may not always fail immediately; the reverse flow of water may cause a prolonged buildup of fatigue and the repetitive impact of the water hammer, which may eventually result in a loss of system integrity.
Properties and Application
Check valves are two-port valves and therefore have two openings: one for fluid to enter and the other for fluid to exit. Check valves feature only one inlet and one outlet. They are powered by a pressure difference. When the upstream pressure exceeds a specified threshold, the check valve opens automatically without further action. The minimum operating pressure is an important feature shared by all check valves, known as the cracking pressure.
Check valves are utilized in a variety of pumping and fluid flow applications. Examples include chemical processing, pulp and paper, food processing, water and wastewater treatment, industrial, marine, mining, pumps, pipelines, power generation, and HVAC. These are just a few of the many uses for check valves.
Understanding Non-Return Valve
Non-return valves are critical because they function in a unique style. They are an essential feature that helps in a typical retention system to prevent the return of water or reflux due to pressure loss or a reduction in the supply and flow of water. This contributes to improved thermostatic tapware safety and precision.
Non-return valves are unidirectional, which means that water can only flow in one direction. They open due to the force of the liquid going in one direction and close due to the action of gravity attempting to return the water in the opposite direction (counter-flow). The spring’s motion aids in closing the valve.
A non-return valve, in essence, enables fluid flow in just one direction. The valve is designed and installed to ensure that fluid running through the pipe flows in the correct direction, particularly when pressure circumstances create reversed flow. When fluid flows through the non-return valve, an acceptable pressure drop occurs in the system. Typically, the valve’s design takes this into account when creating the device.
Properties and applications
They are two-port valves with two openings in the body; one is for fluid to go in, and the other for fluid to leave. Non-return valves are typical of different types. Common variants include the
- Spring-loaded
- Swing
- Clapper
- Swing check valves.
- Flap check valves
- Duckbill
- Dual Disc check valves
- Tilted Disc check valves
- Silent check
- Ball
Non-return valves are used in many different applications. Non-return valves, for example, are widely used in mixing loops in heating and cooling systems to assure appropriate functioning, as well as in domestic water systems to avoid backflow.
Check Valve and a Non-Return Valve: What is the Difference?
We’ve determined that both valves are necessary and serve similar tasks. In a nutshell, the design of a non-return valve permits it to prevent the backflow or reverse flow of a medium or fluid while also protecting the pump from damage caused by surge pressures caused by water hammer when the pump is shut off.
The check valve, often known as a one-way valve, permits fluid to flow through it only in one direction.
Factors to Consider when Choosing between a Non-Return Valve and a Check Valve
Type of Fluid
The type of fluid being conveyed through the system is one of the most significant factors to consider.
A check valve, for example, may be adequate to prevent backflow, provided the fluid is clean and non-toxic. However, a non-return valve may be necessary to ensure the water supply remains safe if the fluid is contaminated or potentially harmful.
Size of Valve and Pipe
Another essential factor to consider is the size of the valve and the pipe it will be installed in.
Check valves are usually more suitable for smaller pipes and lower flow rates, whereas for larger pipes and higher flow rates, check valves may be required. Choosing a valve that is appropriately sized for the specific application is essential to ensure optimal performance and safety.
Reliability and Maintenance
Reliability and maintenance requirements are also essential when choosing between check and return valves.
Check valves have fewer moving parts and are generally easier to install and maintain than non-return valves, which can be more complex and require more specialized tools or expertise to repair.
Cost
In general, check valves are less expensive than non-return valves. Still, it’s important to remember that the long-term costs of maintenance, repairs, and potential damage from backflow may outweigh the initial savings.
Additionally, the overall efficiency of the valve is essential to consider, as this can impact the plumbing system’s energy consumption and operating costs.
