How to Size Variable Flow Control Valves
- 1). Determine the flow rate requirement. For instance, in a reactor design, the temperature is critical for safe results. This temperature is usually controlled using control valves on a steam jacket. The control valve varies the flow of steam into the jacket which alters the temperature.
- 2). Determine the minimum and maximum flow rates the control valve must be designed to handle. If the reactor requires a low temperature for start up, then the valve must have the ability to open the steam flow to 10 to 25 percent. Once the reaction is initiated, the temperature may need to be increased and the valve must open to 75 percent. Accurate control is critical.
- 3). Determine the maximum pressure drop through the variable control valve. The pressure drop determines how much steam, liquid or other substance can pass through the valve. If the pressure drop is too high, the valve may be operating at 100 percent which exceed the parameters of most system processes; this would result from faulty design or inaccurate implementation. Once all of the process specifications have been determined, your control valve manufacturer will match a product to your requirements.
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