THEORY OF OPERATION
5-2
The PID sensor for the AreaRAE is located in a small cavity in
front of the UV lamp. The other sensors are mounted next to
the PID sensor. A diaphragm pump is installed inside the
monitor enclosure to draw an air sample into the sensor
manifold and then distribute it to all sensors.
NOTE:
The gamma radiation sensor on the AreaRAE Gamma
and AreaRAE Gamma Steel does not rely on pumped air.
A single-chip microprocessor controls the operation of the
alarm buzzer, LED, pump and light sensor. It measures the
sensor readings and calculates the gas concentrations based
on calibration to known standard gases. Collected data is
stored in non-volatile memory so that it can be sent to a PC for
record keeping. RS-232 transceivers provide a serial interface
between the monitor and the serial port of a PC. A 2-line by 16-
character LCD display is used to show the readings. The user
interacts with the monitor through three keys on the front panel
keypad.
A rechargeable lithium-ion battery or a six C-cell alkaline
battery pack powers the monitor.
Note:
The printed circuit board of the monitor is connected to
the battery pack even when the power is turned off. Therefore,
it is important to disconnect the battery pack before servicing or
replacing sensors or other components inside the monitor.
Severe damage to the printed circuit board may occur if the
battery pack is not disconnected before servicing the unit.