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The up arrow to the left indicates increasing alarm values for the LEL profile. Alarm
values 1 to 3 correspond to an increase in gas concentration.
The configuration software checks that the data entered by the person doing the
programming is correct. There are general rules for example:
•
The minimum alarm threshold must not be less than 5% of the detector full scale.
•
The value of alarm 2 cannot be equal to or less than the value of alarm 1. Same
for alarm 3 with respect to alarm 2.
The horizontal red bars indicate, for each alarm, the range within which the value can be
set.
Note: for LEL profile (flammable gases) the alarm value cannot be higher than 60% LEL
(limitation for group II equipment, EN 60079-29)
In the "Oxygen Deficiency" Profile, the value of Alarm 1 will be higher than that of Alarm
2, which in turn will be higher than that of Alarm 3.
Note: Oxygen in the air we breathe has a concentration of approximately 20.9% and thresholds of 19%
(Al1), 18% (Al2) and 17% (Al3) are normally set to detect oxygen deficiency.
The "Out-of-Scale" value is typically fixed at 100% of full scale. Only if a fourth Alarm
threshold becomes necessary, this value can be modified and used as a fourth Alarm
threshold.
The "Hysteresis" indicates which signal variation will be ignored when it occurs near
the alarm threshold.
Changing Alarm Levels
The Alarm threshold values can be modified in steps by clicking on the keysand
to the right and left of the horizontal bars; or by directly inserting a numeric value in the
appropriate field to the right of the horizontal bar. Once the value of an Alarm threshold
has been modified, the range of the red bars of the other Alarm thresholds will also be
modified. If the entered Alarm value is outside the allowed limits, it will not be accepted
by the software and must be modified in order to continue programming.
NFG-8
NFG-8_manu-inst_ITA
Fig. 4.5.3 e) Alarm threshold setting screen
Installation and Operation
Manual
Doc. M-040.1-NFG8-EN
Rev A.3
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NOTIFIER ITALY
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