Heath Consultants Gasurveyor 500 Series - Manual (Page 16)

GASURVEYOR 3-500 USER HANDBOOK
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The option is to have the instantaneous alarms activated.
It is the responsibility of the user to ensure that the alarm
levels, where set in the instrument, are appropriate for
the safe operation and legal requirements for the country
/ industry in which the unit is being used.
Alarm Functions
The Gasurveyor 3-500, by default, has the alarm function
on the flammable range disabled.
Where the alarm function is enabled, the instrument has
the facility to have either latching or non-latching alarms.
Latching means that when the alarm level is exceeded,
the LED will flash (visual) and the sounder will pulse
rapidly (audible). Latching alarms are cleared manually,
by a double press of Button Two , after the detected
gas level has fallen below the alarm limit.
Each alarm has to be acknowledged individually, e.g. If
both LOW (10%) and HIGH (20%) instantaneous alarms
have been set, then both would have to be acknowledged
individually if LEL is greater than 20%. If the audible
and/or visual indicators are set to off then the display
alarm function would need to be acknowledged in the
same way. Alarm display example is shown in Figure 2.3.
Figure 2.3 LEL Alarm Display Example