What is Cv value of valve?

What is Cv value? The valve flow coefficient according to the JIS standard, represents the flow capacity in US gallons/minute of 60° F pure water when it is flowing through the valve with a pressure difference of 1 psi at the specified travel (operation range).

How do you calculate valve Cv?

Cv by definition is the number of gallons per minute (GPM) a valve will flow with a 1 psi pressure drop across the valve. For example a valve with a Cv of 10 will flow 10 GPM with a 1 psi pressure drop. The formula used to select the valve Cv with the specified differential pressure is: Cv=GPM/((SQ RT(∆P)).

What is Cv unit?

In the U.S. system of units, the Cv coefficient is the number of U.S. gallons per minute of water that will pass through a given orifice area at a pressure drop of 1 PSI. An orifice or valve passage which has a Cv coefficient of 1.00 will pass 1 GPM of water (specific gravity 1.0) with a pressure drop of 1 PSI.

How do you calculate the flow coefficient of 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.

Is a higher or lower CV better?

The higher the coefficient of variation, the greater the level of dispersion around the mean. It is generally expressed as a percentage. The lower the value of the coefficient of variation, the more precise the estimate.

What is a good CV value?

Basically CV<10 is very good, 10-20 is good, 20-30 is acceptable, and CV>30 is not acceptable.

What is rated Cv and calculated Cv?

Thus, rated Cv is Cv attained at full open position. In my opinion, calculated Cv is a Cv value calculated at particular conditions (P1, P2, flow rate, specific gravity etc.). Conditions can give you min Cv, max Cv or a Cv value somewhere between those two. So when selecting a valve min and max Cv are of importance.

What is a good Cv value?

Is valve CV dimensionless?

CV: The Flow Coefficient, CV, is a dimensionless value that relates to a valve’s flow capacity. Its most basic form is Q=Flow rate and ∆P=pressure drop across the valve.

What is CV in air flow?

Cv — the coefficient of flow — is one standard for expressing the flow capacity of devices used in a pneumatic system. Many manufacturers around the world have adopted Cv as the standard value to express the flow capacity of their components.

What is Cv in air flow?

How do you calculate valve CV?

Cv by definition is the number of gallons per minute (GPM) a valve will flow with a 1 psi pressure drop across the valve. For example a valve with a Cv of 10 will flow 10 GPM with a 1 psi pressure drop. The formula used to select the valve Cv with the specified differential pressure is: Cv=GPM/((SQ RT(∆P)).

What control valve CV means and how to calculate it?

When sizing a control valve, the most common approach is to calculate the flow coefficient, Cv which is a measure of the capacity of the valve body and trim. A valve Cv can be described as the number of gallons per minute (GPM) at 60oF (15.5oC) that will pass through a valve with an associated pressure drop of 1 psi.

What does CV rating mean on a water valve?

CV stands for the “coefficient of flow” of a valve, and is further defined as the flow rate in gallons of 60°F water that will pass through a valve in one minute at one-pound pressure drop. A CV of 1 then, means that one gallon of water passed through a valve in 1 minute at 1 pound DP.

Is valve CV important for ON/OFF control?

Cv is not normally a concern for on/off valves, but there might be applications for which you would have to consider specifying the required flow through an on/off valve: 1) Liquid dump valves. They are normally fitted in service where liquid level buildup is very slow (e.g. in certain KO Drum services).