“cv” is a term constantly used in selecting valves.

Cv factor for valves. This is our valve c v calculator. Cv flow coefficient ratings have several advantages: Cv & kv relation : A cv of 1 then, means that one gallon of water passed through a valve in 1 minute.

Converting between flow coefficient c v and flow. Cv factor can be calculated as following formula. The full closure curve of a ball valve is then the above graph multiplied by the valve’s flow coefficient or factor. A fitting with a high k value passes fluid less easily than one with a low k value.

Scfm air flow through a valve orifice having a cv factor of 1.00 Cv factor is using generally, it is expressed factor for fluid 60°f that flow into valve by us gal/min. The diagram below is a nice tool to simplify the conversion between the different coefficients. In the chart below, we show the approximate cv value of butterfly valves ranging from 2 to 24 and at various disc angles.

It allows you to calculate the flow or c v (flow coefficient) to make the relationship visible between the pressure drop (the difference in pressure between two points in a network transporting a liquid or gas) and the flow rate. The cv value of.0141 is reached at approximately turn 2.3, while the cv value of.0703 is reached at approximately turn 14.6. They simplify the job of selecting an adequately sized valve without wasteful oversizing; The tables below list the full cv vs angle closure and opening curves for various valve diameters:

The conversion factor between two coefficients is indicated with arrows. The process of valve size selection, the same formula is used determine the valve cv necessary for a required flow rate and desired pressure drop. Sometimes, the cv value is given instead of the kv value. Control valve cv refers to the flow coefficient of the valve.

Thus they tend to choke (or cavitate) at smaller pressure drops than globe valves. Kv = 0.865 · cv cv = 1,156 · kv (equivalence between flow coefficients kv and cv) The k v factor of a valve indicates the water flow in m 3 /h, at a pressure drop across the valve of 1 kgf /cm 2 when the valve is completely open. Contrast this with the resistance factor k (the one used for pipe fittings like bends etc).

The following formula is often used using a fluid’s specific gravity (g) where the relationship to water density is already considered. The use of this flow coefficient (c v) calculator leads to a standard calculation to compare valve capacities. The flow of water through a valve at 60°f in us gallons/minute (gpm) at a pressure drop of 1lb/in². This is used as a guide and is not a linear progression.

Cv is the flow coefficient in imperial units. It applies to the factor of the head drop (δh) or pressure drop (δp) over a valve with the flow rate q. The definition of cv is the # of gallons of water that will flow through the valve with a 1 psi pressure differential when the valve is open. For example, a valve with cv of 4.00 will pass 4 times as much flow at the same pressure difference as shown in the chart.

The flow coefficients are in general determined experimentally and express the. .048 substituting in the formula, we have: It is defined as the flow rate in us gallons per minute [gpm] of water at a temperature of 60º fahrenheit with a pressure drop across the valve of 1 psi. And if cv factor is same, flow rate is big so that differential pressure is big.

A valve with a high cv passes fluid more easily than one with a low cv. The flow factor is commonly used outside u.s. Valves are tested by running water through it before publishing the cv value. A simplified version of the definition is:

Butterfly valve cv values vary with the disc angle and valve size. Cv value is an imperial measure of flow in us gallons per minute of water at 60° fahrenheit with a pressure drop of 1 psi across the valve. 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. The valve flow coefficient, cv, is the number of u.s.

The equations below can be used to determine: Cv vs angle closure curve values table. Q = cv x δp g likewise, cv for particular flow characteristics can be determined from On valves or orifices with other cv factors, the flow capacity will be directly proportional to the cv rating.

The cv factor is a standard used by all valve manufacturers. The valve flow coefficient (c v) is a convenient way to represent flow capacity of a valve across a range of fluids and process parameters.the c v calculator will calculate either c v or flow using the supplied additional parameters of fluid, inlet and outlet. If differential pressure is same, flow rate is big so that cv factor is big. Cv is based on the volume flow rate of water at 60°f through a device within one minute at a 1 psi differential.

Flow coefficient is an imperial measurement and is defined as: Because air is compressible, cv must have additional factors built into the equations to compensate for that compressibility. 6.4 “a” constant for 80 psi, from table 2. Gallons per minute that will pass through a valve with a pressure drop of (1) psi.

Q = cv x δp x 62.4 d the formula above utilizes a conversion factor of 62.4 which is the density of water in lbs/ft³. This calculator can be used to help select a valve with enough flow capacity for a given application. C v & flow calculator. Full port valves will have a higher cv than reduced port valves.

The definition of cv is the number of gpm (gallons per minute ) that will pass through the control valve with a pressure drop of 1psi. Kv = 0.864 cv at a particular percentage of opening of valve giving cv = 1 will pass 1us gpm ( at 60 °f) and a pressure differential of 1 psi upstream and downstream across the valve. It can be assumed that the tests are done with water (unless otherwise noted), using a specific gravity of 1.0, 1.2 centistoke viscosity, and a standard temperature of 60 degrees fahrenheit. Cv is the amount of flow in gallons per minute through a valve which results in a 1 psi pressure drop.

A valve cv can be described as the number of gallons per minute (gpm) at 60 o f (15.5 o c) that will pass through a valve with an associated pressure drop of 1 psi. Gallons per minute of water at 60°f that will flow through a control valve at a specified opening when a pressure differential of 1psi. And they allow the designer to predict with reasonable accuracy just how a newly designed system will perform. Compression factor at 80 psi, from table 2.

C v calculator for valve sizing. The required cv range for this application than is.0141 to.0703. For the same pressure conditions, if we increase the valve opening to create cv = 10, it will pass 10 us gpm provided 1 psi pressure drop across the valve (remains same). However, there is a problem with using this equation in pneumatic applications.

The valve flow coefficient cv or its metric equivalent kv has been adopted universally as a comparative value for measuring the capacity of control valves. Flow coefficients cv values the flow coefficiency (cv) of a valve is the rate of gallons per minute of water at 60° f through a fully opened valve at a pressure drop of 1 psi across the valve. Throttling characteristics are shown in the same manner with cv’s at various openings. 8.30 x 12 x 6.4 x.048 cv = 1 x 28.8 = 1.06 any valve, therefore, which has a cv of at least 1.06, will extend our cylinder the specified distance in the required time.

Formulas and cv factors cv factors: In a situation of special travel and differential pressure 1 lbf/in2. Liquid critical pressure ratio factor, f f the liquid critical pressure. They provide a means of comparing the flow capacities of different brands of valves;

The below cv values are used to give an indication of flow rates for ball valves. The complete definition also says that the flow medium must have a specific gravity of 1000 kg/m 3 and a kinematic viscosity of 10 −6 m 2 /s. The cv factor is the number of u.s.

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