RKI Instruments SDM-2012 Standalone Configuration - Manual (Page 37)

Connecting Calibration Gas • 32
Connecting Calibration Gas
The GAS 1 and GAS 2 fittings on the back of the docking station are designed to be
used with a calibration gas cylinder that is fitted with a demand flow regulator. The
AIR fitting may be used with a demand flow regulator and a cylinder of zero
emissions air, but this is not normally necessary since the docking station will
generally be in a fresh air area. If you are using the SDM-2012 with a Gas Tracer and
a zero air cylinder is used, the zero air calibration cylinder must be connected to the
AIR fitting using a 6 inch humidifier tube.
The type of calibration gas cylinder used depends on the gas sensors installed in the
instrument being used with the calibration station. Typically a 4-gas mix will be used if
the instrument being used with the calibration station is a 4-gas GX-2012. If a 5-
sensor GX-2012 is being used, a 100% volume methane cylinder will also be needed.
If a Gas Tracer is being used, a 1000 ppm methane cylinder and a 3-gas cylinder are
needed. If a Gas Tracer with a %volume sensor is being used, a 1000 ppm methane
cylinder, a 3-gas cylinder, and a 100% volume methane cylinder are needed. The
1000 ppm methane cylinder should be connected to the GAS 2 fitting first using a 6
inch humidifier tube. The docking station will begin every bump test or calibration with
the ppm sensor. The user will need to change the GAS 2 cylinder to the 100% volume
methane cylinder (if %volume sensor installed) when prompted to do so by the PC
Controller Program during bump testing and calibration.
Use Table 4 below as a guide in determining which and how many calibration gas
cylinders are appropriate for your system.
NOTE: Do not use a 4-gas cylinder or any cylinder that includes H
2
S when
bump testing or calibrating a Gas Tracer. H
2
S adversely affects the
ppm combustible sensor.
Table 4: Recommended Gas Cylinders
Typical Instrument Types
Recommended Calibration Gas
Cylinder(s)
LEL/Oxy/H
2
S/CO (GX-2012) 4-gas mix with CH
4
/Oxy/H
2
S/CO
LEL/Oxy/CO (GX-2012) 3-gas mix with CH
4
/Oxy/CO
LEL/Oxy/H
2
S (GX-2012) 4-gas mix with CH
4
/Oxy/H
2
S/CO
%Vol CH
4
/LEL CH
4
/Oxy/H
2
S/CO
(GX-2012)
• 4-gas mix with CH
4
/Oxy/H
2
S/CO
• 100% Volume CH
4
%Vol CH
4
/LEL CH
4
/Oxy/CO
(GX-2012)
• 3-gas mix with CH
4
/Oxy/CO
• 100% Volume CH
4