Automatic Valves Instrumentation Piping Valves

Selection of valves

Different structures of different types of valves make them suitable for a wide range of applications. For each application some types of valves are more suitable compared to others. Following list presents some criteria for selection of valves that are most suitable for a given application or service.

Fluid Service

The type of fluid, whether it is gas, liquid, slurry, clean, abrasive etc. determines the type of the valves to be chosen. The chemistry of the fluid service determines the material of construction to be chosen for the valve.

Pressure and Temperature Conditions

The design as wells as operating pressure and temperature conditions affect the type of valve and the material of construction to be chosen, for the given application.

Line Size

The line size is a sometimes a crucial factor in determining the valve type. For very large pipes, compact valves such as butterfly valves may be chosen at times due to the smaller size and weight, instead of gate valves. Availability of a particular type valve for the chosen line size is also an important factor, as all the types may not be available for the chosen line size.

Throttling Characteristics

Only some types of valves offer good throttling characteristics e.g. globe valves and are preferred for the throttling and control applications.

Pressure Loss

For low pressure lines the pressure drop across the valve may be an important criterion, with a small allowable pressure drop across the valve. For example for a normally open on-off valve, a negligible pressure drop is desired across the valve when it is fully open. For such application a gate valve may be chosen as the fully open gate does not obstruct the flow path, thus causing a small pressure drop across the valve.

Special Functional Requirements

The specific function for which the valve is required may impose some special criteria for selecting the valve. For example, choosing a quick opening valve, demands special attention to ball valves.


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