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Are there limitations when installing a wafer-type butterfly valve?

Q: Are there limitations (straight run pipe distances, etc.) that must be considered when installing a wafer-type butterfly valve in a chilled water system and the valve is used as the control valve?

A: Definitely.  Always pose such questions to your valve manufacturer.  Most installation instructions focus on mechanical issues (flanges and the like), and say nothing about piping issues.  When used as a control valve, straight run pipe distances upstream and downstream are advisable (Keystone:  10D to 20D upstream; 3D to 5D downstream http://www.keystonevalves.com/pdf/Keystone%20320%20322%20IOM.pdf).  Also ask about any effect of upstream piping, pumps, valves, etc., on preferred stem orientation (horizontal vs. vertical).

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