What are Modulating Valves
A control system is a process which consists of control valves, actuators, controllers, and sensors. The goal of the control system is to provide maximum regulation to the plant operator or plant personnel. Modulating valves provide an essential means of controlling the variables inherent in regulating a control system.
Modulating valves are devices that are used to regulate control loops in a process. One plant may have multiple control loops, which all require control valves to monitor and control the process variable of the particular loop. Pressure, level, temperature, flow, etc., must all be maintained within specific set parameters in order to ensure a quality end product. Electric, pneumatic, and hydraulic actuators are used in conjunction with positioners and sensors to accurately control modulating valves, which in turn regulate the process media flowing through the system.
The most common control valves are sliding-stem globe valves and angle valves. Other general valve design types include ball, fixed cone, butterfly, gate, check, needle, plug, and spherical. Each type of valve is designed for a particular application, and these valves are rarely interchangeable. Also, each type of valve can be custom assembled to meet the particular process for which the valve is intended to be used.
Modulating valves can fill the need in almost any part of a company’s process control loop. The size, style, and construction of these valves include cage-style valve bodies, disk-stack style valve bodies, angle seat piston valves, single-port valve bodies, balanced-plug cage-style valve bodies, high capacity, cage-guided valve bodies, port-guided single-port valve bodies, double-ported valve bodies, three-way valve bodies, diaphragm valves, rotary valves with butterfly valve bodies, v-notch ball control valve bodies, eccentric-disk control valve bodies, eccentric-plug control valve bodies, sliding cylinder valves with directional control, spool, piston valves, air operated valves, relay valves, or pinch valves.
The regulation of flow must be maintained at a sufficiently linear pace to stay within the specified operating parameters of a process control system. Modulating valves are integral to regulating the control loop, and they directly influence profitability with their performance. Improperly selected valves will prove to be detrimental to the performance of the control loop and safety system.