Compare Model Drawings, CAD & Specs Availability Price
250e gas inlet pressure and flow control module
Pressure and Flow Control Module, Gas Inlet, 1 Set Point, Analog Error Meter
3 Weeks
3 Weeks
250e gas inlet pressure and flow control module
Pressure and Flow Control Module, Gas Inlet, 1 Set Point, LED Display
250e gas inlet pressure and flow control module
Pressure and Flow Control Module, Gas Inlet, 4 Set Points, Analog Error Meter
250e gas inlet pressure and flow control module
Gas Inlet Pressure and Flow Control Module, 4 Set Points, LED Display
3 Weeks
3 Weeks

Configuration Options

  250e gas inlet pressure and flow control module 250E Pressure and Flow Control Module, Gas Inlet, Series 250E


  • Type
    250E Gas Inlet Pressure and Flow Control Module
  • For Use With
    148J, 248D, and 154B Valves (A special version of the 250E is required to drive the 154 control valve. Contact Applications Engineering.)
  • Accuracy
    0.25% of Full Scale 0.1, 1 or 10 VDC selectable on front panel
  • Power Input
    115/230 VAC, 50-60 Hz, 50 Watts
  • Power Output
    ±15 VDC @ 250 mA (to power input transducers)
  • Signal Input
    0 to ±0.1, 1 or 10 VDC
  • Output Signal
    Input transducer signal: 0-5, 10 VDC into >10K Ohm load
    Pressure control signal: 0-10 VDC
  • Display
    Standard: analog error meter
    Optional: 4½ digit LED input signal display
  • Input Impedance
    >200K W
  • Mounting
    bench-top or rack-mount
  • Control Loop Tuning Phase
    Phase lead: 0.05 sec to 10 sec
    Gain: 0.2% to 100%
  • Dimensions
    9.5 inches W x 3.5 inches H x 9.0 inches D
  • Remote Control
    Analog set point input: 0 to 5 VDC into 40K Ohm load
    Multi-set point select (option): ground closure to select (one or four set points)
    Valve close or auto operation: ground closure to select
    Process limits (option): logic level and relay closure adjustable 0.5 to 100% of set point


Process Control

Process control can be manually adjusted through a front panel potentiometer or remotely programmed with a 0-5 VDC analog signal for profile generating. With the multi-set point option, a simple ground closure will select one of four preset set points. The basic 250E provides a simple analog error meter to show deviation of actual versus desired set point. It is also available with an optional 4½ digit LED display which provides a readout of the input transducer signal and eliminates the need for a separate display instrument. A Process Limit Option provides logic level and relay closure when actual pressure or flow exceeds a preset percentage of desired set point. These limits are adjustable from 0.5% to 100% of set point.

Upstream Pressure or Flow Control System

A pressure/flow control system consists of three basic parts: 1) a process sensor, 2) a PID controller, and 3) a control element. In the simplest single-gas control system (see figure), a pressure transducer or mass flow meter measures the process pressure or gas inlet flow rate. The 250E PID controller compares the measured pressure or flow to the desired set point and adjusts the gas flow control valve as necessary to achieve set point.

Upstream Pressure Control System with Four-gas Ratio

For pressure control with multiple gases, the 250E can be used as the master controller to several mass flow controllers (see figure). In this configuration, multiple MFCs are slaved to the output of the 250E, which adjusts the total flow to achieve the desired pressure, while the flow electronics maintains the desired gas ratio/mixture.

Downstream Pressure Control With up to Four Independent Gases

Many processes require a constant total flow, as well as ratio of the inlet gases, yet still require a constant pressure. In this case (see figure), the inlet gases are controlled independently of the pressure control. The 250E is used to operate a valve located in the gas ballast line located between the process chamber and pump. With the upstream gas inlet flow rate (total and ratio) held constant by the MFCs and the electronics, the 250E adjusts the gas ballast flow to achieve the desired pressure set point.

Compatible Control Valves

MKS control valves are solenoid-actuated proportioning control valves designed for precise control of gaseous flows in the range from 0.1 sccm to 200 slm. The 250E control module is compatible with 148, 154 and 248 control valves.

The 148J flow control valve is a metal-sealed design for high purity applications and for the delivery of hazardous gases where minute leakage to atmosphere cannot be tolerated. It controls flows in the range of 10 to 30,000 sccm.

The 154B high flow control valve is designed for flow rates from 20 to 200 slm and uses a patented balanced-forces control valve. Unlike pilot valves and other magnetically-actuated solenoid valves, the 154 enables fast response to set point changes without oscillations over a wide range of inlet pressures. Because the 154 requires higher drive current, the 250E must be modified for this. Use with the 154 should be noted when placing orders.

The 248D general purpose flow valve is an elastomer sealed, general purpose valve for applications from 10 sccm to 10,000 sccm.

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