5
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.
H2S). (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
