LEFT:
Dual analysis is achieved with
heater elements positioned in separate
flow chambers.
RIGHT:
Probe and reference air streams
are simultaneously monitored for thermal
conductivity. Differences in air composition
are indicated by differences in the heater
element currents.
10.0 Technology
The leak detector measurement is based on thermal conductivity comparisons between
the probe air and a reference air. The device employs a dual thermistor technology that
measures the ratio of [probe]:[reference] heat exchange values and displays the results on
an LED scale (Figure 4). Under ideal operating conditions, a ratio of 1:1 indicates identical
air samples for both [probe] and [reference], and therefore, no leak is present.
Because of slight differences in air temperature and/or humidity between the reference
inlet (Figure 1) and the probe tip, a small response indicated by a single red or yellow LED
light is generally insufficient to positively identify a gas leak. Small to moderate leaks are
reliably indicated with 3 red or 2 yellow LED lights and an intermittent beep. Larger leaks
are indicated with all red or yellow LED lights lit and a continuous audible alarm.
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