In order to properly size a check valve, you must determine the minimum velocity required to fully lift the disc. Then find the mean velocity of flow in the piping system and ensure it is greater than or equal to the minimum required velocity.
How do I choose a check valve?
Some of the things you may need to consider are fluid compatibility, flow characteristics, headloss, non-slam characteristics and total cost of ownership. For optimal performance, it is of course important to choose your valve respecting the characteristics of each specific installation.
What size valve should I use?
So, how do you size a control valve anyway? When sizing a control valve, the rule of thumb is to size it so that it operates somewhere between 20-80% open at maximum required flow rate and whenever possible, not much less than 20% open at the minimum required flow rate.
What are the 5 types of check valves?
Most common types of Check valves are swing, lift (piston and ball), butterfly, stop and tilting-disk.
Do check valves come in different sizes?
As simple as this logic is, check valve sizing is largely misunderstood. Check valve “sizing” refers to how much the valve’s disc opens in order to accommodate media flow through a pipe – a vital component to the system’s overall functionality.
How do you choose a cracking pressure check valve?
An inexact but informative way to test cracking pressureA simple air pressure test is an easy way to estimate the cracking pressure of a spring loaded check valve. It involves attaching a pressurized air line with a control valve and a pressure gauge to the inlet side of the check valve.
When should check valves be used?
Check valves are used in many different applications. For example they are often placed on the outlet side of a pump, to protect the pump from backflow. Centrifugal pumps, the most common type of water pumps, are not self-priming, and therefore check valves are essential for keeping water in the pipes.
How do I calculate valve size?
The basic valve sizing equation Q = Cv√∆P can be used to calculate pressure drop, flow rate, or the flow coefficient. For solutions other than water, a correction for a difference in specific gravity of the solution is necessary. This revised formula would be: Q = Cv[√∆P/Sg] with Sg = specific gravity of the liquid.
Why proper valve sizing is important?
The performance of control valves can have a dramatic effect on plant operating efficiency, overall profitability and asset life cycle costs. A correctly sized control valve can provide significant quantifiable savings as well as increase process availability, reduce process variability and reduce maintenance costs.
How do you calculate flow through a valve?
The volume flow rate for liquids can be calculated by multiplying the fluid velocity times the flow area. Thus, Cv is numerically equal to the number of U.S. gallons of water at 60°F that will flow through the valve in one minute when the pressure differential across the valve is one pound per square inch.
Should a check valve be before or after pump?
On booster pump applications, a check valve can be placed on the suction or discharge of a centrifugal pump. If an additional check valve is required, it should be placed after the pressure tank to allow the pump and discharge pipe to remain pressurized.
Does check valve reduce water pressure?
Check valves do not reduce pressure, they actually help maintain it. In the setup you describe, it might work. However you will DEFINITELY need another check valve on the outlet of the tank to prevent the high pressure flow from backwashing in through the bottom, since there is no shuttoff/float valve there.
How close should check valve be to pump?
Many well pumps have built-in check valves. Even if a pump does have a built-in check valve, we recommend that a check valve be installed in the discharge line within 25 feet of the pump and below the draw down level of the water supply.
What is the difference between check valve and stop check valve?
Stop check valves allow you to start and stop the flow in your piping system. They are different in that they allow you to regulate the flow as well. Stop check valves are basically check valves that have an override control to stop flow regardless of flow direction or pressure.
What are the three types of check valves used in hydraulics?
Hydraulic valves are subdivided into three main categories: directional control valves, pressure control valves and flow control valves. All valves operate a different function in the hydraulic system.
When would you use a swing check valve?
Swing check valves have many uses, from sewage systems and wastewater treatment to firefighting, power plants, and various household items. One of the most commonly known examples of this valve type is the swing check valve that allows water to enter a toilet’s tank while blocking the reverse flow.
