Chapter One: General Information Introduction
5
Chapter One: General Information
Introduction
The MKS Type 250E Pressure/Flow Controller will control any one of a variety of flow valves to
accurately maintain a set pressure or flow. The 250 controller can provide a ±15 VDC output
and accepts inputs from a variety of pressure transducers and mass flow meters. Two controllers
can be combined to provide two gas ratio control. The front panel controls allow selection of the
input range, control loop tuning, and automatic and manual valve control. An error meter is
provided on standard units to assist you in tuning the control loop. External signals can
command the external set point, close the valve, or switch to the manual control. A DVM option
is available to provide 4½ place display of the control variable.
Typically, a pressure control system consists of three basic parts:
•
The pressure sensor
•
The controller and control valve
•
The system whose pressure is to be controlled
The pressure sensor will usually be an MKS Baratron
®
Capacitance Manometer with an output of
0 to 10 VDC. Provision for other outputs (0 to 1 VDC or 0 to 100 mV) has been built into the
controller so that other transducers may be used. The pressure (vacuum) system will consist of a
chamber and a pumping system. Typically, users want to control the flow of gas entering the
system while the system pressure is maintained by the 250 controller and a control valve.
The controller’s new 9-pin Type “D” connector allows you to connect the unit to a variety of
control valves (refer to Table 3, page 16). If you install the 250 controller into an existing
system that uses the old (hex) connector cables, an adapter cable is required (refer to
Valve
Connector
, page 20, for more information.
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