Theory Of Operation; Convectron Gauge; Differential Pressure Sensor; Piezo Resistive Diaphragm Sensor - HELIX GRANVILLE-PHILLIPS Convectron ATM Instruction Manual

Figure B-1 Convectron heat-loss gauge and Piezo resistive diaphragm sensor
Connects differential pressure
sensor board to main PC board
B.1 Piezo resistive diaphragm
sensor
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Convectron ATM Vacuum Gauge Module Instruction Manual
Appendix B Theory of Operation
The module measures gas pressures from 1 x 10
Vacuum chamber pressure is measured by a Convectron
convection-enhanced Pirani heat-loss gauge. The differential between
atmospheric and vacuum chamber pressures is measured by a Piezo
resistive diaphragm sensor. Figure B-1 illustrates the Convectron gauge and
diaphragm sensor.
Ribbon cable
The Piezo resistive diaphragm sensor measures the differential between
atmospheric and vacuum chamber pressures. Changes in the differential
between atmospheric and vacuum chamber pressures cause the diaphragm
to move.
The differential pressure sensor connects to the vacuum chamber through a
port on the Convectron gauge. A second port, extending from the sensor, is
open to atmosphere and provides the pressure comparison that enables
differential pressure measurement.
The differential pressure sensor provides a direct, accurate,
electromechanical measurement of differential pressure regardless of the
gas composition. Changes in pressure on the diaphragm cause activation
and deactivation of relays at programmable setpoints that correspond to
increasing and decreasing differential pressures.
–4
Piezo resistive diaphragm
sensor
Measures differential between
atmospheric and vacuum
chamber pressures
Convectron heat-loss Pirani gauge
Measures vacuum chamber pressure as a
function of heat loss through sensing wire
Torr to 1000 Torr.
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