Detcon CX-IR - Manual (Page 23)

Model CX-IR
The menu item appears as: Set Gas Factor.
To calculate the correct Gas Factor (Table 2), take the Gas Factor of the target gas and divide by the Gas
Factor of the cal gas. The calculated value is the correct number to enter into the menu as the Gas Factor.
For example, if calibrating with methane when propane is the target gas, the correct Gas Factor to enter would
be 0.63/1.0 = 0.63.
For example, if calibrating with butane when ethane is the target gas, the correct Gas Factor to enter would be
0.38/0.72=0.53.
Table 2 shows the Gas Factors of most combustible hydrocarbon gases that will be measured. Find the gas of
interest for the cal gas and the target gas and follow the above instruction. If there is a mixture of target gases,
use a weighted approach to determine the correct Gas Factor.
For example, if the target gas was 50% butane and 50% pentane and the cal gas was methane, the correct Gas
Factor would be calculated and entered as ((0.5 x 0.77) + (0.5 x 0.77)) / 1.0 = 0.77.
Table 2 Gas Factors
Gas Factor Gas Factor Gas Factor
Acetic Acid 2.00 Decane 1.53 Naphthalene
Acetone 1.21 Ethyl Alcohol 0.35 n-Nonane 1.53
Benzene 1.00 Ethane 0.38 n-Octane 1.34
1,3-Butadiene 1.80 Ethyl Benzene 1.07 n-Pentane 0.77
Butane 0.77 Ethylene 2.39 Propane 0.63
Iso-Butane 0.72 n-Heptane 0.98 iso-Propyl Alcohol 0.54
Butene-1 0.67 n-Hexane 1.00 Propylene 0.80
n-Butyl Alcohol 0.63 Dimethyl Ether 0.40 Toluene 1.00
iso-Butyl Alcohol 0.63 Methane 1.00 Vinyl Acetate 1.43
Cyclohexane 0.89 Methanol 0.41 Vinyl Chloride
Cyclopropane 0.45 Methyl Ethyl Ketone 0.77 Xylene 1.00
From the Set Gas Factor text scroll, hold the magnet over PGM1 or PGM2 until the arrow prompt appears and
continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to scroll Set
Factor). The display will then switch to X.XX (where X.XX is the current gas factor). Swipe the magnet
momentarily over PGM2 to increase or PGM1 to decrease the gas factor level until the correct value is
displayed. Hold the magnet over PGM2 for 3 seconds to accept the new value. The display will scroll Factor
Saved, and revert to Set Gas Factor text scroll.
Move to another menu item by executing a momentary hold, or, return to normal operation via automatic
timeout of about 15 seconds (the display will scroll Set Gas Factor four times and then return to normal
operation).
3.4.5 Bump Test
Bump test checks the response of the sensor with the indication of response limited to the display only. The
bump test mode allows the performance of the sensor to be checked without firing the alarms of any attached
control systems. The results of the bump test will not affect the reading register on the Modbus™ output.
The menu item appears as: Bump Test
From the Bump Test text scroll, hold the magnet over PGM1 or PGM2 until the "
►" prompt appears and
continue to hold the magnet in place for an additional 3 to 4 seconds (until the display starts to scroll Bump
Test Started).
CX-IR Instruction Manual Rev. 1.2 Page 19 of 34