Process Variables and Control Loops

Process variables typically fall into five different groups pressure, temperature, flow, level, and analytical variables. Each control loop is specifically designed to work with a selected variable. Process technicians monitor many control process variables. 

Although it appears that the primary element is interrupting the flow, this is not the case. Increased velocity across the orifice plate compensates for the restriction. The transmitted signal is sent to a controller that compares the incoming signal with the desired setpoint. If a change is required, the controller sends a signal to a final control element. 

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