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7
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 which measures the ratio of [probe]:[reference] heat exchange values and dis-
plays 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 four red LED lights, larger leaks are indicated with all red LED lights or yellow LED
lights lit and the continuous alarm is audible.
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.
Figure 4 Schematic layout of the Leak Detector technology.
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