5 Functions
5-2. Alarm function
FP-300AGZS
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5-2. Alarm function
5-2-1. Gas alarm
The gas monitor detects a gas from a change of color which occurs on the detection tape with special
reagent applied on it when the detection tape contacts a specific amount of gas within a unit time. This
means, the gas concentration display cannot provide accurate information unless a unit time (detection
cycle) passes. However, in the event of a presence of high concentration gas, alarm must be triggered
immediately.
The alarm activation of the gas monitor uses the theory shown in the following figure to enable quick
response.
NOTE
For 4 - 20 mA output, concentration indication is performed at the end of a measurement cycle. Therefore,
the alarm level output lags behind the alarm triggered from alarm contact output.
Detection cycle
Change of t
ape c
olor
Measurement
time
Measurement
time
Concentration
indication
Change
Conc
entration convers
ion
Change of t
ape c
olor
Detection cycle
Change
Conc
entration convers
ion
Concentration
indication
Measurement
time
Measurement
time
Trigger
Trigger
Trigger
