13 composer bulk flow control configuration, 1 general, 2 sensor installation (bulk flow) – INFICON Composer Gas Concentration Controller User Manual
Page 73: Section 3.1.13
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Composer Operating Manual
3.1.13 Composer Bulk Flow Control Configuration
3.1.13.1 General
Composers with firmware version 4.00 (LED display) or 5.00 (LCD display) and
higher are designed to have an alternate configuration that allows automatic
feedback control of Bulk Flow, or Flux, in addition to the standard Concentration
Control. Within this context, Bulk Flow is defined as the product of
Concentration (mole%) and Bubbler Flow (sccm).
Bulk Flow Control manipulates only the Bubbler’s MFC to maintain a constant
Target Flux into the reactor, i.e., Total Flow Control is not available. This is
different than Concentration Control, which may also manipulate a second MFC
to provide constant precursor flux while maintaining constant total flow. In some
situations Bulk Flow Control can provide faster response to changes in the
Target Flux.
The Bulk Flow Control configuration is selected by activating SW#8 on CFGR2
(configuration switch bank 2). The analog I/O option board is required. This
board allows the read-back of the Bubbler’s MFC and also generates a 0 to 5
volt analog equivalent to the measured Concentration or other parameters, see
. Internal or external control of the Bulk Flow target
is electrically toggled by respectively “grounding” or “opening” pin 21 (Input #4)
of the Composer’s System I/O connector. A 0 to 10 volt analog signal
proportional to either Concentration, Frequency or F/F2 is also available on the
standard Concentration Out BNC, see
.
The voltage range of the analog inputs is set by SW#7 on CFGR2. When the
switch is “off” the range is 0 to 10 volts. Activating the switch reduces the range
to 0 to 5 volts.
NOTE: The state of a configuration switch is only read during an initialization
sequence when power is first applied to the Composer. Changing the
state of the switch while the controller is “on” does not result in a change
of the selected features.
3.1.13.2 Sensor Installation (Bulk Flow)
The Composer Transducer is installed downstream of the Bubbler and before
any dilution or push flow additions in the Bulk flow control configuration. Other
useful information is found in
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