RKI Instruments SDM-2009 PC Controlled Configuration - Manual (Page 22)

17 • Hardware Setup
Connecting Calibration Gas
The GAS fitting on the back of the docking station is 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.
The type of calibration gas cylinder used depends on the gas sensors installed in the
instrument being used with the calibration station. A 4-gas mix, LEL/Oxygen/CO/H
2
S,
is used if the instrument being used with the calibration station is a 4-gas unit. If the
instrument does not have an H
2
S channel, then a 3-gas mix, LEL/Oxygen/CO, is
used. Although a 4-gas cylinder will work for an instrument of any gas combination, if
you have multiple instruments with various gas combinations, you may want to keep
a 4-gas cylinder and a 3-gas cylinder to help preserve the charcoal filter on the CO
sensor in instruments without an H
2
S channel. Use Table 2 below as a guide in
determining which calibration gas cylinder is appropriate for your system. See “Spare
Parts List” on page 108 for a list of available cylinder part numbers.
To connect calibration gas to the SDM-2009, do the following:
1. If the area around the docking station is not considered a fresh air area (an
area free of combustible and toxic gases and of normal oxygen content,
20.9%) install a tube not longer than 10 feet on the filter attached to the AIR
fitting on the back of the docking station and route it to a fresh air area or
connect a cylinder of zero air with a demand flow regulator to the AIR fitting.
2. Install the demand flow regulator on the calibration gas cylinder.
3. Connect the demand flow regulator to the GAS inlet fitting using the 3 foot
length of 3/16 inch ID sample tubing provided with the docking station.
Table 2: Recommended Gas Cylinders
Typical Instrument Types
Recommended Calibration Gas
Cylinder(s)
LEL/Oxy/H
2
S/CO 4-gas mix with CH
4
/Oxy/H
2
S/CO
LEL/Oxy/CO 3-gas mix with CH
4
/Oxy/CO
LEL/Oxy/H
2
S 4-gas mix with CH
4
/Oxy/H
2
S/CO
LEL/Oxy 3-gas mix with LEL/Oxy/CO
Oxy/CO 3-gas mix with LEL/Oxy/CO
Oxy/H
2
S 4-gas mix with LEL/Oxy/H
2
S/CO