1-2
1 Introduction
Model 1220
Teledyne Analytical Instruments
1.2.1 System Chassis (19” Rack)
The System Chassis provides structural support and electrical intercon-
nection for the Control Unit and Channel Modules (up to eight Channel
Modules may be installed). These latter plug into the sockets of the system
chassis. Terminal strips at the rear of the System Chassis provide for
external electrical connections.
1.2.2 Control Unit
The Control Unit handles power distribution to the entire system. The
main power is controlled by a switch on the front panel and the system fuses
are accessible from the front. The Control Unit also contains common
alarm relays, which indicate alarm conditions whenever any of the Channel
Modules alarm.
1.2.3 Channel Modules
Each channel module is a complete, self-contained instrument including
integral power supply, and requires only external AC power. A channel is
operational simply when plugged into the System Chassis.
Because a channel module plugs into the control module, channels can
easily be added after installation to monitor additional locations on any
control module originally supplied with less than eight channels. Channel
Modules in the same System Chassis may still be configured independently.
1.2.3.1 Main Features of the Channel Module
The main features of the Channel Module Include:
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High resolution 0-100% LEL LCD display readout
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Drop in replacement for Model 122 instruments
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1MAN calibration capability
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Membrane switch control
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Rugged sensor design
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2 sensors per channel option
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Microprocessor based electronics
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Two concentration alarms with adjustable set-points
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Sensor failure alarm
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User friendly touch key controls
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Passcode protection