*Technician use only
– This procedure
must be carried
out by a suitably
qualifi ed technician in
accordance with these
instructions and the
standards set down
in their particular
industry/country.
AT-G-DETECT
Gas Sensing System
Check / Calibration Procedure
A. INTRODUCTION
The frequency and nature of testing or calibration may be determined by local regulation or
standards.EN378 and the FGAS Regulation require an annual check in accordance with the
manufacturer’s recommendation.
• For 1 level models, Aquilar recommends an annual check consisting of resetting units
electrically to the factory calibration settings and carrying out a bump test to ensure correct
operation. A gas calibration should be carried out every three years.
• For 2 level models, Aquilar recommends annual checks by resetting units electrically to
the factory calibration settings, a bump test and replacement of the sensors with a pre-
calibrated certi
fi
ed sensor every three years. The alternative to replacement is an on-site
gas calibration. Sensor replacement may be more cost e
ff
ective, eliminate end of life
concerns and constantly renew the detection system
If the sensor is exposed to a large leak it should be tested to ensure correct functionality by
electrically resetting to the factory calibration settings and carrying out a bump test.
There are two concepts that need to be di
ff
erentiated: bump test and calibration
LEAK DETECTION SOLUTIONS
1
BUMP TEST
This consists of exposing the sensor to a gas.
The objective is to establish if the sensor is
reacting to the gas and all the sensor outputs
are working correctly. A quanti
fi
ed bump test
is one where gas of a know concentration is
used.
CALIBRATION
This consists of exposing the sensor to a
calibration gas, setting the “Sensor Standby
Voltage”, the alarm set points “Alarm
Threshold Voltages” and checking/adjusting
all the outputs so that they are activated at
the speci
fi
ed alarm gas concentrations when
exposed to this gas.
It is required by EN378 to record the check results in the Logbook
Before you carry out the test or calibration
procedure:
1. Advise occupants, plant operators and
supervisors
2. Check if the AT-G-DETECT is connected
to external systems such as sprinkler
systems, plant shut down, external
sirens and beacons, ventilation etc. and
disconnect as instructed by the customer.
3. For 1 level systems you must deactivate
the 3 minute alarm delay, if selected, by
removing jumpers JP1 to o
ff
position. For
2 level systems upon power up there is a
delay of 3 minutes before the green power
LED turns on.
4. For bump test or calibration, AT-G-
DETECT’s should be powered up overnight.
5. If a unit has been powered o
ff
for a
short time, say due to maintenance, it
will normalise within a few minutes. If
sensors have been in long term storage
or have been turned o
ff
for a long period,
normalisation would be much slower.
However, within 1-2 hours sensors
should have dropped below the low
alarm level and be operational. You can
monitor normalisation progress exactly by
monitoring the sensor output, see Table 1.
Unit 30, Lawson Hunt Industrial Park,
Broadbridge Heath, Horsham, West Sussex,
RH12 3JR
+44 (0) 1403 216100
[email protected]
www.aquilar.co.uk
