11 Definition of Terms
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11
Definition of Terms
% LEL
A percentage unit of the concentration of a combustible gas assuming the lower
explosive limit (LEL) of the combustible gas as 100. LEL (Lower Explosive Limit)
refers to the lowest concentration of a combustible gas in air capable of causing
explosion when ignited.
vol%
Gas concentration indicated in the unit of one-hundredth of the volume
ppm
Gas concentration indicated in the unit of one-millionth of the volume
Calibration
Find relationship of the readings, display values or setpoints with the actual values
by using the calibration gas.
Maintenance mode
When maintenance is performed on the alarm system, the alarm contact is
disconnected, and a signal to indicate the maintenance mode status is sent out to
the external output signal. As a result, maintenance can be performed on a single
unit of the alarm system.
Initial clear
The reading is unstable for seconds after the power is turned on. To prevent
malfunctions for that period, the alarm contact is deactivated. In addition, a signal
to indicate the initial clear status is sent out to the external output.
Zero suppression
A function to cut off the influences of environmental changes, interference gases,
etc.
Alarm delay time
A function which temporarily suspends activation to prevent a false alarm caused
by noise from its outside.
Response time
The time to trigger an alarm after introducing a gas with the concentration 1.6
times higher than the alarm setpoint.
(The delay time in a tube for the case of connecting a suction tube outside is
excluded.) The response time of the alarm system is 30 seconds at maximum.
Inhibit
The gas detection function is temporarily suspended during maintenance etc. of
the alarm system. This is also called "point skip", which has the same function.