Flow Coefficient Cv vs. Flow Factor Kv
Comparing flow coefficients Cv to flow factors Kv.
The flow coefficient  C_{v}  or the flow factor  K_{v}  are commonly used to specify capacities of control valves.
Flow Coefficient  C_{v}
It is often convenient to express the capacity and flow characteristic of a control valve in terms of the
 Flow Coefficient  C_{v}
The flow coefficient  C_{v}  is based on the imperial units system and is defined as:
 the flow of water through a valve at 60 ^{o}F in US gallon/minute at a pressure drop of 1 lb/in^{2}
The flow coefficient is commonly used in the U.S.
Flow Factor  K_{v}
The metric equivalent of the flow coefficient  C_{v}  is based on the SIsystem and is called the
 Flow Factor  K_{v}
The flow factor  K_{v}  is defined as
 the flow of water with temperature ranging 5  30 ^{o}C through a valve in cubic meters per hour (m^{3}/h) with a pressure drop of 1 bar
The flow factor is commonly used outside U.S.
Converting between Flow Coefficient C_{v} and Flow Factor K_{v}
The relationship between C_{v} and K_{v} can be expressed as:
 C_{v} = 1.16 K_{v} (1)
 K_{v} = 0.862 C_{v} (2)
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