Dual Plate vs. Swing Check Valve

Check valves are automatic valves designed to open in the presence of forward flow and close when encountering reverse flow. Various types of check valves exist, such as swing check valves, lift check valves, and dual plate check valves. Their primary purpose is to safeguard mechanical equipment in a piping system by preventing fluid from reversing its direction.

 

Check valves are automatic valves designed to open in the presence of forward flow and close when encountering reverse flow.

Various types of check valves exist, such as swing check valves, lift check valves, and dual plate check valves.

Their primary purpose is to safeguard mechanical equipment in a piping system by preventing fluid from reversing its direction.

 

In addition to protecting against reverse flow, check valves also play a crucial role in halting significant backflow in the event of a pipe break and preventing flow towards lower pressure areas.

Typically, these valves do not require manual operation; instead, they operate automatically based on fluid flow or flow reversal.

In the case of a swing check valve, the closure member swings around a hinge mounted in the seat.

Illustrated in Figure 1 is a swing check valve where the disk moves away from the seat due to the force of the water, keeping the valve open.

Figure 1 is a swing check valve

 

A swing check valve is a cost-effective option, but it is susceptible to a high slamming effect. While slamming is a common issue with check valves, there is limited published information on preventing and predicting its occurrence.

Check valve slam occurs when the pump stops, and the forward flow reverses, moving back toward the pump before the check valve can fully close.

Closing the valve to stop the reverse flow results in slamming and water hammering. Contrary to the belief that the noise is due to the disk impacting the seat, we posit that it is related to the rapid reverse flow.

 

Furthermore, we propose that not only the return flow but also the weight of the disk contributes to slamming, hammering, and shutoff characteristics of the valve.

Research aimed at understanding the slamming and closing characteristics of check valves has characterized check valve slam as a two-step process.

The first step involves the flow reversing after pump stoppage, possibly moving backward through the check valve before full closure.

The second step occurs when the closure member abruptly stops the reverse flow.

 

The recommendation was made that a check valve should either close swiftly before the onset of reverse flow or close gradually once reverse flow has commenced.

To achieve rapid closure, it was proposed that one method is to aid the motion of the valve disk with a spring [8].

In this regard, dual plate check valves employ a spring to facilitate the closure of the valve disk.

Consequently, dual plate check valves are favored over swing check valves due to their lower susceptibility to slamming effects.

 

Moreover, a dual plate check valve can be crafted to be more space-efficient compared to a swing check valve, especially in a wafer (flangeless) design.

Figure 2 illustrates the contrasting closing actions of dual plate and swing check valves.

The slamming effect is significantly reduced in a dual plate check valve as compared to a swing check valve, primarily because the closure is aided by the force of springs rather than relying solely on the weight of the valve disks.

Additionally, the distribution of disk weight in a dual plate check valve occurs between two parts, further contributing to its lowered slamming effect in comparison to a swing check valve.

Figure 2, Image Source：Jonloo

The advantages of a dual plate check valve over a swing check valve extend beyond space efficiency and a reduced slamming rate.

When considering the total cost, encompassing initial cost, maintenance expenses, and energy consumption, a dual plate check valve proves to be more cost-effective than a swing check valve.

Research indicates that the swing check valve is nearly twice as expensive.

Furthermore, the swing check valve experiences higher pressure drop, leading to increased energy costs.

Additionally, the relatively weak connection of the disk in a swing check valve to the body raises the likelihood of disk dismantling during operation, contributing to higher maintenance costs.

 

Faq

Q: What factors should be prioritized when choosing a valve?

A: Prioritize factors such as flow rate, pressure conditions, and media compatibility based on your specific system requirements.

Q: Are Dual Plate Valves suitable for high-pressure applications?

A: Yes, Dual Plate Valves are often used in high-pressure applications due to their quick closure and low-pressure drop characteristics.

Q: How often should Swing Check Valves be inspected for maintenance?

A: Swing Check Valves should be inspected periodically, with frequency depending on the specific conditions and flow rates in your system.

Q: Can Dual Plate Valves be customized for specific industrial needs?

A: Yes, Dual Plate Valves can be customized to meet the specific requirements of different industries, providing versatility in application.

Q: What is the average lifespan of both valve types?

A: The lifespan of Dual Plate and Swing Check Valves depends on factors such as maintenance, operating conditions, and the specific environment, making it essential to follow recommended maintenance schedules.