8
2 Features
Dynamic or constant signal for ALPPM
For the
ALPPM
alarm there are two options for cycling the audi-
ble and visual signals:
●
dynamic (
dynamic signal
)
●
constant
With the dynamic signal option the cycle speed is dependent on
the measured gas concentration. The higher the concentration
above the alarm threshold, the shorter the interval between two
signals. This applies up to a concentration of 5 % vol. H
2
. Above
a concentration of 5 % vol. H
2
the cycle speed remains constant.
With the constant signal option the cycle speed is always inde-
pendent of the measured gas concentration. The interval between
two signals is always constant.
The default setting at delivery is dynamic signal. If the dynamic
signal option is switched off, the device automatically switches
to a constant signal.
See
Section 3.3.5 on page 30 for information on how to switch
off the dynamic signal.
2.2
Sensors
The device features two types of sensor:
● Gas-sensitive semiconductor (SC) for hydrogen
● Thermal conductivity sensor (TC)
Application
Measuring range (H
2
)
Sensors
Inspection above
ground
0.0 ppm — 5 % vol.
SC, TC
Measuring in bar holes 0.0 % vol. – 100 % vol.
TC
House
0.0 ppm — 5 % vol.
SC, TC
Gas measuring
0.0 % vol. – 100 % vol.
TC
