The flow coefficient - Cv - or the flow factor - Kv - are commonly used to specify capacities of control valves.
Flow Coefficient - Cv
It is often convenient to express the capacity and flow characteristic of a control valve in terms of the
- Flow Coefficient - Cv
The flow coefficient - Cv - is based on the imperial units system and is defined as:
- the flow of water through a valve at 60 oF in US gallon/minute at a pressure drop of 1 lb/in2
The flow coefficient is commonly used in the U.S.
Flow Factor - Kv
The metric equivalent of the flow coefficient - Cv - is based on the SI-system and is called the
- Flow Factor - Kv
The flow factor - Kv - is defined as
- the flow of water with temperature ranging 5 - 30 oC through a valve in cubic meters per hour (m3/h) with a pressure drop of 1 bar
The flow factor is commonly used outside U.S.
Converting between Flow Coefficient Cv and Flow Factor Kv
The relationship between Cv and Kv can be expressed as:
- Cv = 1.16 Kv (1)
- Kv = 0.862 Cv (2)
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