651B-D251 MKS Instruments Pressure Controller

The MKS Instruments 651B Series Pressure Controllers are a self-tuning pressure controller for throttle valves. It can supply +15 Volts to power and provide a readout for an attached capacitance manometer. The self- tuning feature of the 651 unit determines system characteristics necessary for control. This feature takes into account time constants, transfer functions of the valve and plumbing, valve gain, pump speed, and many other important parameters when determining the system characteristics. The 651 unit also includes an adjustable soft start function (to minimize turbulence in the chamber and contamination of the process), local/remote transducer zeroing capability, and two process limit relays to indicate if the pressure deviates from the desired trip points.

Located on the front panel is a key lock switch used to select front panel or rear panel control. The switch can lock the front panel controls as a safety measure to prevent accidental command entries. The default window display on the front panel shows the pressure readout and the valve position (% open). The pressure readout can be displayed in units of Torr, mTorr, mBar, pBar, Pascal, kPa, cmH,0, or inH,O. Five reprogrammable setpoints are provided, each one having the option of being setup for pressure or position control. Valve open, close, and stop functions are also provided on the front panel for use in system setup and diagnostics.

The 651 instrument has a high-powered driver to operate all MKS type throttle valves, including valves up to 4" (102 mm) with vacuum shut-off capability, giving the unit a control range from 10 to 760 Torr with the appropriate pressure transducers. All MKS unheated and 45C temperature-controlled, linear Baratron transducers are compatible with the 651 controller, which is equipped with a low-capacity power supply. The 651 unit can be optionally equipped with a high-capacity power supply, enabling compatibility with 100C temperature-controlled, linear Baratron transducers. The 651 unit also contains a battery-backed memory module which stores configuration and /earned system information while power is off.