Dual Valve Pressure Controllers PC Series - Alicat Scientific
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The PCD pressure controller was created in response to the need for fast, accurate, repeatable and cost effective pressure control instrumentation designed specifically for closed volumes. Historically, closed volume pressure control was done by using a pressure controller or switch and a bleed port. This method, although effective, resulted in wasted process gas, poor repeatability, and poor accuracy.
The PCD dual valve pressure controller works by using a modified PID loop control that enables the instrument control of each valve while only allowing one valve to open at a time. By opening one valve at a time the unit can effectively reach a setpoint quickly and accurately while keeping gas venting to an absolute minimum. Speed and Control By utilizing modified PID loop controls and proportional control, the PCD pressure controller is able to quickly and accurately reach a defined setpoint. Since the PCD uses similar control algorithms as those in the PC Series single valve pressure controllers, the control speed of the PCD is measured at less than 1/10th of a second! Cost Savings The PCD series pressure controller uses only one valve at a time automatically switching the PID control to the required valve. By opening and closing one valve at a time, gas venting required to maintain a setpoint is significantly reduced. Less exhausted gas is less wasted gas. Companies using exotic bottled gases could save thousands of dollars a year by switching to a PCD pressure controller. Accuracy The PCD uses a modified PID closed loop control and a proportional control on each valve resulting in a total full scale accuracy of +/- 0.25% for most units. Optional higher accuracy is available for more demanding applications. The modified loop and proportional control not only produces increases in precision control of the process pressure in closed or nearly closed systems, it also eliminates dead-band that is inherent in other pressure controllers that use pressure switches and on/off valves. Repeatability Processes designed for consistency require instrumentation that is repeatable. The PCD series dual valve pressure controller has an impressive repeatability spec of +/-0.08% of full scale. All Alicat PCD series dual valve pressure controller calibrations are NIST traceable. Alicat PCD series pressure controllers come standard with the following options: •Fully functional digital display with pushbutton control Optional features and equipment •High accuracy calibration |
The Alicat PCD dual valve pressure controller utilizes independently controlled intake and exhaust valves to achieve fast and stable pressure control inside a closed, or dead headed, system. Proprietary control software and electronics allow the PCD controller to input process gas into a chamber and also exhaust process gas. The PCD pressure controller has been used in a variety of industries ranging from semiconductor manufacturing to biopharmaceutical testing. 
