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Technical Description
General Operation
2020 is a microprocessor controlled air monitor for measuring the
presence of photoionizable chemicals in air at parts-per-million
levels. The block diagram in Figure 29 shows the main components
of 2020.
Sample Out
Sample In
Photoionization
Inlet
Pump
Detector
Filter
Power
Display and
Microprocessor
Supply
I/O Connector
Keypad
Electrical Connections
Gas Connections
Figure 29
2020 Block Diagram
The microprocessor controls the components of the instrument and
interprets and records the signal generated by the photoionization
detector (PID). Recorded data and setup information entered into
the microprocessor's memory are retained when 2020 is turned off.
A pump continuously pulls the air under test through 2020's PID.
The PID converts the concentration of photoionizable chemicals in
the sample into an electrical signal. The microprocessor subtracts
any background from the signal and divides this signal by a
sensitivity obtained by calibrating with a standard gas of known
concentration. This concentration appears on 2020's display and,
depending on the values entered through 2020's keypad, an alarm
status may be displayed and an audio signal may be heard.
2020 can detect thousands of different types of airborne gases and
vapors and its response depends on the type as well as the
concentration. 2020 does not distinguish one type of chemical from
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Table of Contents
Troubleshooting
