What is meant by CV of a valve?
The flow coefficient, or Cv, is a universal capacity index and is simply defined as the number of US gallons of water per minute at 60F that will flow through a valve with a pressure drop of one psi. Sometimes pressure drop is described as pressure differential or delta P.
How do I choose a valve size?
When sizing a control valve, the rule of thumb is to size it so that it operates somewhere between 20-80% open at maximum required flow rate and whenever possible, not much less than 20% open at the minimum required flow rate.
What is valve size?
The first step in finding the size of a valve is to determine the flow. coefficient (Cv) that is required for the system. Cv factor is defined as. “the number of US, gallons per minute of 60F water that will flow through. a fully open valve with a 1 psi drop across it”.
How do I choose a valve?
The right valve choice means matching the valve’s size to expected flow through the system. Know the chemical compatibility requirements. The valve materials need to be compatible with the gases or liquids flowing through it. Plastic valves usually resist harsh or corrosive chemicals better than metal valves.
What is the best type of valve to use for isolation?
For steam service, parallel slide valves are the preferred option in which high temperature swings occur after valve closure. Wedge gate valves may be used as an alternative for general isolation duty or if good, low pressure leak tightness is required.