What is the Cv calculation of a control valve?
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 and KV in control valve?
The Valve Coefficient (Cv – in Imperial unit) – the number of US GALLON PER MINUTE of water at 60 °F that will flow through a valve at specific opening with a pressure drop of 1 psi across the valve. The flow factor (Kv – in Metric unit) – the amount of water that will flow in m3/hr.
How do you calculate Cv value?
The formula for the coefficient of variation is: Coefficient of Variation = (Standard Deviation / Mean) * 100. In symbols: CV = (SD/x̄) * 100. Multiplying the coefficient by 100 is an optional step to get a percentage, as opposed to a decimal.
Is KV same as Cv?
Kv is the flow coefficient in metric units. Cv is the flow coefficient in imperial units. It is defined as the flow rate in US Gallons per minute [gpm] of water at a temperature of 60 fahrenheit with a pressure drop across the valve of 1 psi.
What is CV in PRV?
Valve Flow Coefficient (Cv) is a valve’s capacity for a liquid or gas to flow through it. It is technically defined as “the volume of water at 60°F (in US gallons) that will flow through a valve per minute with a pressure drop of 1 psi across the valve.”
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 the main purpose of control valve?
A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.
What are the components of control valve?
Basic parts of control valves
- DIAPHRAGM CASE.
- . DIAPHRAGM.
- DIAPHRAGM PLATE.
- ACTUATOR SPRING.
- ACTUATOR STEM.
- SPRING SEAT.
- SPRING ADJUSTER.
How do you calculate the CV of a 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)). If the specified ∆P is 4 psid and full flow is 10 GPM the calculated CV is 10/SQ RT of 4 = 5.
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).
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.
What is the control valve characteristic curve?
The installed control valve characteristic curve plots the valve open percent versus the flow through the valve , and this plot is dependent on the conditions specific to the system. For example, if the control valve flow setpoint is fixed at 250 gpm, the pressure drop required by the control valve to achieve that flow rate will be related to the other sources of pressure drop (and pressure addition) that exist in the system.