Flow Coefficient Cv and Flow Factor Kv

Comparing flow coefficient Cv with flow factor Kv

The flow coefficient - Cv - and the flow factor - Kv - are commonly used to specify the capacity of control valves.

Flow Coefficient - Cv

It is often convenient to express the capacities and flow characteristics of control valves 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)

Related Topics

  • Steam and Condensate - Steam & condensate properties - capacities, pipe sizing, systems configuration and more
  • Control Valves - Control Valve terminology, bodies, trim, flow characteristics, Cv and Kv sizing, noise, actuators and positioners
  • Fluid Mechanics - The study of fluids - liquids and gases. Involves various properties of the fluid, such as velocity, pressure, density and temperature, as functions of space and time.
  • Process Control - Instrumentation and process control systems - engineering and documentation
  • Control Valves and Equipment - Sizing and dimensions of control valves & equipment in steam and condensate systems
  • Piping Systems - Dimensions of pipes and tubes - dimensions, materials, capacities - pressure drop calculations and charts - insulation and heat loss diagrams
  • Pipe Sizing - Sizing steam and condensate pipes - pressure loss, recommended velocity, capacity and more

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