Valve selection is a important activity of a material engineer or process engineer. Key to valve selection is as follows:

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Valve selection is a important activity of a material engineer or process engineer. Key to valve selection is as follows:

A. First determine type of conveyed fluid : Gas, Liquid, Slurry or Powder.

B. Determine nature of fluid : 

1. Substantially neutral : not noticeably acid or alkanline, such as various oils, nitrogen, air, gas, drinking water etc.
2. Corrosive – markedly acid, alkaline or otherwise chemically reactive.
3. Hygienic  – materials for food, drug, cosmetic or other industries.
4. Slurry – suspension of solid particles in a liquid can have an abrasive effect on valves etc. Non-abrasive slurries such as wood-pulp slurries can choke valve mechanisms.

C. Determine required operation

1. ‘On/Off” – Fully open or fully closed.
2. Regulating – including close regulation (throttling)

D. Other factors affecting choice

1. Pressure
2. Temperature
3. Stem operation method.
4. Closing time required e.g. quick closing.
5. Cost
6. Availability of valve
7. Special installation problems – such as welding valves into lines. Welding heat will sometimes distort the body and affect the sealing of small valves.