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Quick Start Guide
4
Sensor calibration
4.1
Factory calibration gases
Table 4-1: Rosemount 625ND Non-Dispersive Infrared Combustible Gas
Sensor Module
Gas type
Methane (default)
Propane
Butane
Ethane
Ethylene
Note
To order a Rosemount 925FGD with the optional ISO/IEC gas
concentrations used for factory calibration, you must add the
optional IEC model code to the configured model number. You can
also change this in the field by selecting sensor settings in the local
operator interface (LOI) menu or via HART
Note
To ensure proper calibration, verify that the correct concentration of
calibration gas is used in correlation with the concentration settings
selected in the transmitter.
4.2
Calibration options
The calibration cup (part number 00625-2012-0001) is the preferred
method for sensor calibration.
The calibration cup attaches to the sensor by fitting over the pre-
installed IP filter on the Rosemount 625ND Infrared Sensor. Refer to
Figure 4-1
diameter [OD]) plastic gas tubing.
24
Range
0-100% LEL
0-100% LEL
0-100% LEL
0-100% LEL
0-100% LEL
to see how to attach ¼-in inner diameter (ID) (⅜-in outer
Default 50% lower
explosive limit
(LEL) calibration
gas per National
Fire Protection
Association (NFPA)
standards
2.50%/volume
1.05%/volume
0.95%/volume
1.50%/volume
1.35%/volume
communication.
®
April 2023
Optional 50%LEL
calibration gas
per International
Organization for
Standardization
(ISO)/IEC
standards
2.20%/volume
0.85%/volume
0.70%/volume
1.20%/volume
1.15%/volume
Rosemount 925FGD
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