Chapter 7: Theory of Operation
98
Chapter 7: Theory of Operation
Technique of Measurement and Control, Electronics
The design of the MF1 flow controller incorporates an advanced flow sensor, a new control valve
and an optimized bypass. The latest generation two-element sensing circuit provides accurate,
repeatable performance even in low flow ranges (< 10 sccm). Low temperature effect from ambient
temperature change and a low attitude sensitivity effect are also ensured. The newly optimized
sensor/bypass arrangement minimizes the flow splitting error for gases with different densities,
which dramatically improves measurement accuracy when gases other than the calibration gas are
used.
The surface mount digital, processor controlled electronic circuitry allows optimum adjustment of
the sensing and signal conditioning circuitry and provides tuned flow control for fast response to
any set point in common with excellent stability.
Figure 11: Assembly
The flow controller type MF1 measures and controls the gas flow rate according to a given setpoint
signal, which may be an analog signal or a digital command when using a MF1 with digital
interface. The control range is from 2 % to 100% of full scale. The accuracy of the flow
measurement is ± (0.5 % of Reading + 0.2 % of F.S.).
Sensor
Valve
Housing
Bypass
Valve
Plug
Electronic
Board
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