Check valves are the one-way gates that only let water flow in one direction. Condensate pumps and sump pumps both use a check valve for backflow protection.
So, that’s the main job of a check valve. But you may be curious about ins and out of a check valve e.g what is a check valve, what are the types, how does it work.
You are welcome. This article will clarify every single confusion of a check valve you’re used to having, so, stay with us!
Okay, now see what we’ve kept for you.
What is a Check Valve?
As we said above, this valve is a one-way valve in which the flow can freely run one way. It has another name; Non-return valve/NRV. The valve will open by the pressure of the fluid passing through a pipeline.
But the flow will be going forward. If there’s any reversal flow, the valve will be closed automatically. So, these valves count on the line fluid to open and close.
How’s the structure of a check valve?
It will help you to recognize the parts of a check valve. A check valve consists of:
- Body
- Cover plate
- Disc
- Body seats
- Hinge
- Hinge pin
- Nut
- Cotter pin
- Stud bolts
- Gasket
- Washer
What are the types of check valves?
There are 8 available check valves in the market. The list is here:
1. Swing check valve
This one is available in 2 designs; straight body and y-patterned. The disk is apart from the body using a hinge pin and seals against the seat that is integral to the body.
You can install this type in both horizontal and vertical positions. But it’s not a good fit for vibrant flow. Because of the long disk travel and inertia of the disk, it’s closure response is a bit slow.
2. Tilting Disk check valve
This type fits between two flanges and offers a compact installation for large diameter applications.
As a swing check valve, it also can be installed both horizontally and vertically. But unlike a swing one, it’s suitable for vibrant flow and it offers you a quick closure response.
3. Wafer type check valve
The low-weight character of the wafer type check valve offers a simple space-saving installation between the companion flanges. It has short face-to-face dimensions.
This is mainly for those cases where a low-pressure loss is essential. It means, this valve’s opening and closing will occur at a low-pressure difference over the valve disc.
If you want, you may know about when your pool pump loses pressure.
This type of check valve is popular enough for the compact design and comparably low cost.
4. Disc check valve
Low operating pressure is common between the disc and the wafer type check valves. It’s designed to be sandwiched between flanges.
It allows being installed in any position even in vertical pipelines where the fluids flow downwards.
5. Piston check valve
This type is dedicated to protecting pumps or similar equipment and allows the flow only in one direction.
You may know about how do pool pumps work which will help you to understand the pump better.
A piston check valve is designed with globe valve bodies which produce an increased drop pressure in the pipeline. It provides a quick closure as well as a tight seal.
6. Ball check valve
The ball check valve works well in both water and wastewater applications. It operates simply and mainly used in small pumps in lower head systems. Remember, the ball check valve has a high tendency to slam for the ball’s high inertia long stroke.
For this, as safety practice, you have to add an optional roll-bar to the piping system.
7. Dual plate wafer check valve
The most efficient and versatile design is this one. It’s also termed as a silent check valve or a butterfly check valve. Hence, two spring-loaded plates are hinged on a central hinge pin.
Whenever the flow decreases, the plates close by action of torsion spring before flow reverses happen. It’s pocket saving to install and to maintain.
8. Non-slam check valve
A problem that you face using the swing check valve can be minimized by a Non-slam one. Make sense?
Listen, swing check valves close abruptly due to gravity and cause pressure surge that results in shock waves. This high pressure is not good for the piping system.
So, these are the types of check valves. You can choose one of them which fits well for you.
Frequently asked questions
We will answer some frequently asked questions and hope that you will find yours too.
Q-1: Do I need a check valve from the pump to the pressure tank?
Ans: It depends on your well. I mean, whether it has any check valve or not. But if it doesn’t have one then it’s beneficial to use a check valve between the pump and pressure tank.
Q-2: Do check valves have trouble with hot water lines?
Ans: Yes, check valves and backflow preventers can create problems with hot water lines due to thermal expansion. In some cases, this can cause the relief valve to open intermittently.
Q-3: What’s cracking pressure for a check valve?
Ans: When the valve begins to open, the cracking pressure is when there becomes a constant flow, no that pressure when it first opens.
Q-4: Is it a must to inspect the backflow prevention assembly?
Ans: Yes, you have to test it at least annually. It will help you to ensure that the device is functioning properly.
Clear now? These questions are the most asked about a check valve, so we picked them.
Conclusion
In the end, we can say that we are totally clear about a check valve, can’t we? Actually, a check valve’s function is not hard to know.
You are now ready to purchase a check valve. Because ‘what is a check valve’ is not a hard question for you. Moreover, you now know the types and structure of a check valve too.
So, are we successful to make your confusions as clear as water? We hope that it’s a yes!