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the cell frequency ƒ
sample
through the cell. Flow stops momentarily while the cell frequency ƒ
tration in the sample gas is a function of the delta frequency (∆ƒ) between ƒ
dryer capable of drying the reference gas to ≤10 ppb is required (AMETEK Part Number A.560040907 or
equivalent).
General
The sample cell, moisture generator, solenoid valves, pressure regulators, and flow regulation orifices
are contained in an oven and maintained at constant temperature (nominally 60°C). All analyzer func-
tions are microprocessor controlled by the on-board microcomputer. Operating parameters and system
values are set and changed using the 18 button keypad on the front of the unit or the RS-485 serial
interface.
Continuously updated moisture data, system operating parameters, system messages, and alarm condi-
tions are displayed on a 4 line, 80 character display. Two 4 to 20 mA dc isolated analog outputs and an
RS-485 serial interface provide communication between the analyzer and user recording or data acquisi-
tion equipment.
The analyzer also provides the following contact closure signals:
• System Alarm: Activates when a condition exists which makes analyzer output question-
able. Such conditions include cell temperature alarm, calibration error, and computer mem-
ory failure. Please refer to (Chapter 6) for more information.
• Concentration Alert: Activates when a system value exceeds the user set limits for either
one of two user specified parameters. This alert is factory defaulted to be linked to moisture
concentration only, but may be linked to other system parameters such as cell temperature
and pressure. Please refer to (Chapter 4) for more information.
• Range Alert: Indicates when the range on analog output channel 1 shifts from high to low
or high to low range. The channel 1 output range can be selected manually or configured
for auto-range. Please refer to (Chapter 4) for more information.
All alarm relay contacts are factory configured to be fail-safe; refer to (Chapter 5): Flags1 for
information on configuring for reverse operation of alarm relay contacts.
Note that the Concentration and Range Alerts can be configured to provide a "data valid" signal which
alerts recording equipment that analyzer is in equilibration, calibration, or zero mode rather than
sample analysis mode.
NOTE
Refer to (Chapter 4-6): Alarms and Alerts for more information on configuring the alarms.
is recorded. During the second period of the cycle, dry reference gas* flows
is recorded. Moisture concen-
ref
and ƒ
An external
sample
ref
Overview 1-3
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