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10.9
Operation under low oxygen levels
• If an electrochemical detector sensor is used in an atmosphere comprising less than 1%
oxygen for over one hour, the measurement may be an underestimate.
• If a semiconductor detector sensor is used in an atmosphere comprising less than 10%
oxygen, the measurement may be an underestimate.
• If a semiconductor detector sensor is used in an atmosphere comprising less than 18%
oxygen, the measurement may be an underestimate.
10.10 Installation and calibration
• The detector will be installed with the sensor cell pointing downwards.
• The detector should be calibrated with the gas to be measured. With respect to
combustible gases only, and in the event it is impossible to calibrate with the targeted gas,
see tables on pages 31 and further for recommended calibration gas and cross gas
interference.
10.11 Functional Safety
The safety function of the OLCT 60 detector is the detection of flammable gases using catalytic
technology or the detection of oxygen using an electrochemical cell and a 4-20 mA current
output proportional to the gas concentration expressed as a percentage of LEL (from 0 to 100%
LEL) or expressed as a percentage of volume of oxygen (from 0 to 30% vol. O2). In the event of
a failure, the output current will assume a fallback value less than or equal to 1 mA or greater
than or equal to 23 mA. The safety function is no longer valid on warm up and during the time it
takes for the sensor to stabilize. During this period, the output current shall be frozen at 2 mA
(maintenance mode).
10.12 Reliability data
The analysis reported by INERIS, report no. CGR 74448 of July 6
assessment of the annual failure rate of OLCT 60 combustible gas detectors equipped with a VQ1
catalytic sensor: λ
annual = 4.7.10
DU
Please note: the calculated failure rates are strictly valid over the actual life time of the sensitive
elements (limited time interval, 3 to 5 years). Past this term, the failure rate is no longer significant
due to aging of the measuring sensors.
NPO60GB
Revision F.2
.
-2
OLCT 60
FIXED POINTGAS MONITOR
USER MANUAL
2006, has allowed the
th
55
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