# Control Valve What is Valve Rangeability?

**URL:** <https://forumautomation.com/t/control-valve-what-is-valve-rangeability/408>\
**Category:** Valves\
**Created:** [April 23, 2015, 10:41pm UTC](https://forumautomation.com/t/control-valve-what-is-valve-rangeability/408 "2015-04-23T22:41:01Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![denizen](https://forumautomation.com/letter_avatar_proxy/v4/letter/d/848f3c/32.png) [@denizen](https://forumautomation.com/u/denizen)\
**Post date:** [April 23, 2015, 10:41pm UTC](https://forumautomation.com/t/control-valve-what-is-valve-rangeability/408/1 "2015-04-23T22:41:02Z")

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Control Valve What is Valve Rangeability ?

Rangeability is the ratio of maximum controllable flow to minimum controllable flow

For the control valve selection rangeability is one of the important selection factor.

Minimum and Maximum Cv of Valves are calculated .If the ratio of Cv Maximum to Cv Minimum is within the rangeability of the selected control valve ,the valve should function properly

Cv - Flow Coefficient

To know more about Control Valve sizing read the article

> [@Instrumentation :How to do Valve Sizing](https://forumautomation.com/t/instrumentation-how-to-do-valve-sizing/370):
>
> Step 1 - Define System For Example : The system is pumping water from one tank to another through a piping system with a total pressure drop of 150 psi. The fluid is water at 70 0F. Design (maximum) flowrate of 150 gpm, operating flowrate of 110 gpm, and a minimum flowrate of 25 gpm. The pipe diameter is 3 inches. At 70 0F, water has a specific gravity of 1.0. Key Variables: Total pressure drop, design flow, operating flow, minimum flow, pipe diameter, specific gravity Step #2: Define a…