There are many different types of components and control valves. Each may have different flow / pressure loss characteristics. Manufacturers of control valves usually publish a Cv flow coefficient or a Kv flow coefficient to describe the flow versus pressure loss characteristics of their control valves in a standardized manner. 


A Cv flow coefficient specifies the volume of water in US gpm at 60°F (15.55°C) that will flow through a valve with a 1.0 psi pressure drop across the valve.


Thus a Cv flow coefficient of 10 indicates that a 1.0 psi pressure drop will occur with a flow of 10 US gpm of water through the valve. Pressure drop for the different fluids and different flow rates can be calculated from the Cv flow coefficient. See the ‘Calculation Theory and Methods of Solution’ section for further details.


A Kv flow coefficient specifies the volume of water in m3/hour at 20°C (68 °F) that will flow through a valve with a 1.0 bar pressure drop across the valve. 


Thus a Kv flow coefficient of 10 indicates that a 1.0 bar pressure drop will occur with a flow of 10m3/hour of water through the valve. Pressure drop for the different fluids and different flow rates can be calculated from the Kv flow coefficient. See the ‘Calculation Theory and Methods of Solution’ section for further details.


The component object is used to model the flow rate / pressure loss of control valves with Cv or Kv flow coefficients.