Cv calculation for gas metric

The cv of the gas at each local distribution zone is continually measured by the national grid who sends this figure to your gas supplier, who then uses it for their calculations. Calculation of pressure loss using the c v method a c v value is defined as the rate of flow of water in us gallons per minute at 60°f at a pressure drop of 1 psi across the equipment. Density ( water density = 1000kg/m³ ) d: The c v values, using us customary units are far more widely reported than k v values, using metric units. Converting from ft3/hr to m3/hr: Following is a complete gas rating chart for metric meters. Dimensional flow coefficient (cv and kv) calculation. In metric units, the same valve above with a specified opening giving cv = 1 will pass 0.862m3/hr of water (at 15 degree celsius) if 1bar pressure difference (δp) exist between upstream and downstream points on each side of the valve. X t 816 x p g 1 cv = q 962 (s.g. The assumptions are such that cv is 38.76mj/m3, with a mj to kw conversion of 3.6. With a metric meter the part units of gas are highlighted in red and those digits are often separated by (i.e. It is defined as the flow rate in us gallons per minute [gpm] of water at a temperature of 60º. How do we get value 1.156 (conversion factor) in formula cv = 1.156kv or cv= 1.156×q×sqrt (g/delta p). Kv is the flow coefficient in metric units. ※3 for p1 and p2, please use pressure close to the valve.

From the equation q = n c ∆t, we can say: You can use 40.0 as a default number if you don’t have the exact figure. C v calculator for valve sizing. This same calculation method can also be used to determine the volume at some other set of conditions. Flow coefficient, cv, and flow factor, kv, are values used to specify the hydraulic capacity of a control valve. Find valve size and valve position of an unlined valve, with flow at 200 gpm and an actual pressure drop of 5 psi for a liquid with a specific gravity of 1.8. Cv =200 √1.8/5 = 200 √.36 = (200)(0.6) = 120 from cv table: Q p = n c p ∆t. With an imperial meter the part units are. The flow coefficient for a control valve which in full open position passes 25 gallons per minute of water with a one pound per square inch pressure drop can be calculated as: ※2 calculation of viscosity correction is necessary when the fluid is liquid and the kinematic viscosity is 20 mpa・s or more and the calculated cv value is 0.01 or less. Please contact us if the fluid specification requires viscosity correction. T = gas temperature in °r (°f + 460) z = compressibility factor assumed at. Ft3 / 35.3 = m3/hr. From cv table, the corresponding valve position is 70% open.

This value is equal to the change in enthalpy, that is, q p = n c p ∆t = ∆h. 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. To correctly model the pressure drop for the entered cv or kv value the density of the gas used in the calculation must be the density of the gas at the outlet of the valve/component. Specific gravity (1 for water) v: Converting from m3/hr to ft3/hr: For measuring the valve capacity of control valves, the coefficient cv or its metric equivalent kv is adopted. In the following section, we will find how c p and c v are related, for an ideal gas. G = specific gravity (air=1.0) t = flowing temperature absolute (ºf + 460) q = 34.3 cv p g the rate of flow of a liquid or gas through a valve depends upon numerous factors such as The relationship between c p and c v for an ideal gas. Flow coefficient is an imperial measurement and is defined as: The determination of the cv of gas is carried out in accordance with international standards and the gas (calculation of thermal energy) regulations, as amended in 1997. Cv is the flow coefficient in imperial units. The flow coefficient or flow factor k v is in general determined experimentally and express the. This is psig (gauge pressure) plus 14.7 (atmospheric pressure) If the flow coefficient is given in si units, it may be converted to u.s.

Cv = (25 gpm) (1 / (1 psi))1/2. To convert mass flow to volume, use the following equation: Subtract the new meter reading from the previous reading to work out the volume of gas used. Due to this density reduction the gas is accelerated up to a higher velocity than the one reached by an equivalent liquid mass flow. Units by dividing it by 54.9. At constant pressure p, we have. The use of this flow coefficient (c v) calculator leads to a standard calculation to compare valve capacities. You should enter not selected one. K = q / sqrt X t) g = 1222 where: Qg = gas flow in standard cubic feet per hour p1 = upstream (inlet) pressure in psia t = absolute temperature in ºr. M3/hr x 35.3 = ft3/hr When p2 is less than 1/2 p1, use 1/3 p1, for p2 in formula. It is defined as the flow rate in cubic meters per hour [m3/h] of water at a temperature of 16º celsius with a pressure drop across the valve of 1 bar. Si and metric cv flow coefficients si (international standard) cv flow coefficients are the number of liters per minute of water which will pass through a given orifice or passage at a pressure drop of 1 bar.

A 2 valve has a cv of 120 at 40%. Head drop (high of fluid) δp: (ºf + 460) p2 = downstream (outlet) pressure in psia psia = absolute pressure. In effect this means that the fluid data for the fluid zone associated with the control valve must be defined for the approximate pressure condition at the outlet. Convert from cubic feet to kilowatt hours (multiply by 31.6586). C v & flow calculator. 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. This calculator can be used to help select a valve with enough flow capacity for a given application. You should enter not selected one. The flow of water through a valve at 60°f in us gallons/minute (gpm) at a pressure drop of 1lb/in². This reduces the calculation as follows. (metric units) the flow coefficient k. These regulations stipulate when and where the cv of gas is measured and the type of instrument to be used. Typically, a gas supply has a cv between 37.5 and 43.0 mj/m cubed. This is our valve c v calculator.

= mass flow in lbs/min r = universal gas flow constant (1545 ft lbf/(lb mol)(°r)) divided by m.w. The larger this value, the higher the flow rate through the valve will be at a given pressure drop.

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