Compur Ex plus Gas Detector User Manual download pdf (Page 9)

Triple Plus+ and Triple Plus+ IR Operation

2.2 Display

The information on the display is dependent on the type of sensors installed in

the instrument. For each sensor module installed, the display indicates the gas

concentration, the units of measurement (e.g. ppm) and the channel name (e.g.

S). (Each sensor module contains analogue circuitry to support the sensor

and a small digital memory which identifies it to the processor along with cali-

bration data and alarm thresholds.) A quarter of the screen is reserved for each

of a possible 4 gas channels, which means that in the popular ‘triple’ gas con-

figuration one quadrant is left blank. It is often useful to know how the location

of the sensor modules relates to the display. When viewing the instrument from

the top with the sensor grilles facing away, reading the display from left to right

like a book shows the location of the sensors installed from left to right along

the front face. The normal mode of operation is diffusion monitoring whereby

the instrument constantly samples air in its immediate vicinity.

Display options

The instrument may be configured into alternative display modes, by the DISPY

option (see DISPY in section 3.2, Configuration Options). The ON button can

be programmed to switch between modes.

The possible display modes are:

Normal: All gas values, units and names are displayed in real time

Average: The average gas reading since the instrument was switched on is

displayed for toxic sensors. This is indicated by flashing 'avg' with

the sensor name. Non-toxic sensors will display their normal gas

level.

Off: Display reads 'MONITORING' whilst a safe condition is perceived,

and flashes 'GAS HAZARD and EVACUATE AREA 'in alarm condi-

tion.

TWA Toxic: This display mode only affects toxic sensors, and is indicated by

the letters 'TWA' flashing with the sensor name. The gas value

displayed will be the current long-term exposure level. Non-toxic

gas sensors will display their normal gas level.

Peak hold: This options affects the displayed gas value for all sensors, and is

indicated by the letters 'pk' flashing with the sensor name. The

highest gas level that has been read since instrument switch on

will be displayed, or in the case of oxygen, the lowest level read.

The peak that has been retained may be reset to the current gas

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Compur Ex plus Gas Detector User Manual Page 9