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OLCT 60
FIXED POINTGAS MONITOR
USER MANUAL
2.8 Scope of use
Gas sensors have limitations that must be observed (see Special instructions for use in explosive
environments and functional safety).
2.8.1
Presence of specific components
• Vapors from components containing silicone or sulfur can affect the catalytic sensors and
thereby distort measurements. If sensors have been exposed to these types of compounds,
a bump test shall be performed.
• High concentrations of organic solvents (e.g. alcohols, aromatic solvents, etc.) or
exposure to quantities of gas greater than the specified range of measurement can
damage the electrochemical sensors. Inspection or calibration is then recommended.
• In the presence of high concentrations of carbon dioxide (CO2 > 1% vol.), the oxygen-
measuring electrochemical sensors can slightly overestimate the concentration of oxygen
(0.1 to 0.5% volume O2 overestimate).
2.8.2
Operation under low oxygen levels
• If an electrochemical sensor is used in an atmosphere comprising less than 1% oxygen for
over one hour, the measurement may be an underestimate.
• If a catalytic 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.
2.9 Transfer curve
The curve shown gives the transmitter output current
as a function of the gas concentration. If you connect
the transmitter to a different unit than the one
provided by Oldham, you should be certain that the
transfer curve is fully compatible with the input
characteristics of your device to ensure proper
interpretation of the information provided by the
transmitter. Similarly, the unit should provide
sufficient voltage to compensate for any voltage
drop in the cable.
16
Output signal (mA)
Default
Default
Figure 22: OLCT 60 transfer curve
% of the
measuring range
NPO60GB
Revision F.2
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