Finding Pnuematic Actuators
Pneumatic actuators are used in all types of industrial plants and climate zones with specific local conditions. Safety is a primary function and the demand for reliability in pneumatic actuators is high since failure of an actuator may cause toxic leaks in a particular plant. Process-controlled plants have a decades-long operating life and require that actuators be high quality and designed with corrosion protection. Since a particular valve may be a long distance from the operator, an actuator allows the possibility for remote control activation or, alternately, an automatic functionality.
Pneumatic actuators move the valve to the open or closed position, utilizing an automatic switch-off procedure when the set tripping point is achieved, in the case of limit seating. In torque seating, the controls are programmed to switch off at the point of exceeding a set torque limit. This serves as protection against excessive torque; for instance, in the case of a trapped object the controls can discern abnormal twist and switch off from an intermediate position.
Temperature sensors in pneumatic actuators prevent overheating and protect the motor. In some cases the material can be sticky or abrasive, causing valves to lose functionality. In these cases a valve actuator with additional torque is requested by the designer so the problem can be avoided. Occasionally a manual control feature is added to a valve actuator providing extra torque if necessary. In some cases motor current is monitored and will trip the control switch when the limit is reached to prevent burnout during an attempt to move a stuck valve. Actuators with overload protection are available for these applications.
Pneumatic actuators can also be simple on-off devices used to turn a valve completely open (on) or closed (off) when signaled. These typically turn off the actuator motor when not in use and do not provide flow control. Proportional control can be achieved by wiring an actuator to open and close gradually in response to the controller, varying flow to reactors, monitoring filling rates, or controlling temperature with heating or cooling liquid flow. Heating and cooling equipment can utilize valve actuators for dampers, flue vents, and inlets. Heat pumps, gas and oil furnaces, and boilers all benefit from actuators of various appropriate types.
Our pneumatic actuators are an essential part of the automation of process control in a variety of industries, and can be found in a spectrum of designs and dimensions suitable to the specific application required. They can be classified according to their movement, the distance the closing element must cover to completely open or close the valve. Typically, butterfly valve discs swivel on an axis to open or close the passage, globe valve discs move in a short linear stroke, and the gate valve disc moves to cover the entire opening of the valve. Each movement requires a particular type of actuator in order to function correctly, some by multiple complete turns and some by partial turns. The amount of torque and thrust resistance vary considerably and the choice of electric valve actuator must be carefully considered for optimal performance.