Modulating control valves change the flow of fluids, pressure, level, and temperature control of a system. Most modulative values are made up of three main parts: a valve body, an actuator, and a positioner. The positioner, through the actuator, drives the valve based the setting of the control signal. The Maxitrol EXA Star Modulating Valves are equipt with a built-in digital controller that gives a seamless interface with a process controller. The valve has two buttons and a communication LED for the user interface which is used to set the valve for high and low fire settings. In addition, the valve has full open and full close mechanical limits. This feature adds dimension for sizing and applying is significant because it allows the valve to be set up for an entirely different net output depending on pressure supply. The EXA Star Modulating Valve has six electronic connections – two for the power, two for the control signal, and two for the position feedback.
Linear Maxitrol EXA Star Modulating Valves
Maxitrol’s E42, E52, and E62 Series EXA Star Modulating Valves are designed to have a linear relationship between the control signal and flow rate. This flow rate linearization will optimize over a 5:1 turndown ratio with the maximum flow rate determined at 1″ w.c. pressure drop. With applications in areas with atmospheric low-pressure, these modulating valves consistent gain allows the controller’s entire signal range to be utilized and tuning is simplified. This is a significant improvement over traditional designs. Rather than using a ball, butterfly, and poppet valve, the EXA Star modulating valve has a built-in digital controller that provides a seamless interface with the process controller. This allows the installer to set the high fire and low fire settings and establish mechanical limits for the valve.