Detcon IR-700 - Manual (Page 24)

Model IR-700
IR-700 Instruction Manual Rev. 3.1 Page 20 of 40
3.5.3 Set Gas Type& Range
The IR sensor has a slightly different linearization requirement for different groupings of target gases. The
four groupings are 1) Methane (CH
4
) and 2) Heavier Hydrocarbons (H HC) and 3) % by volume (%VOL) and
4) CO
2
. The Set Gas Type menu function is a simple choice between these four gas type groupings.
NOTE: The default value for Gas Type is methane (CH
4
).
The menu item appears as: “Set Gas Type”.
From the Set Gas Type & Range text scroll, hold the magnet over PGM1 or PGM2 until the “” prompt
appears and continue to hold the magnet in place for an additional 3-4 seconds (until the display starts to scroll
“CH4 / H HC / %VOL / CO2”). Swipe the magnet momentarily over PGM2 or PGM1 to change the selection
until the correct choice is displayed. Hold the magnet over PGM1 or PGM2 for 3 seconds to accept the new
value. The display will scroll “Type Saved”, then “Set Range” followed by the currently selected Range.
Momentarily hold the magnet over PGM1 or PGM2 to change the Range Selection until the correct value is
displayed. Hold the magnet over PGM1 or PGM2 for 3 seconds to accept the new value.
NOTE 1: If a gas type of CH
4,
HHC, or %VOL is selected the range can only be set to 100. If
CO
2
gas type is selected range selections are 0.3, 0.5, 1, 3, 5, 10, 15, 20, 25, 50, and 100.
NOTE 2: For CO
2
there are two different plug-in IR sensors. One sensor is used for the ranges
of 0.3, 0.5, 1, 3, and 5. The second is used for the rages of 10, 15, 20, 25, 50, and 100. These
sensors cannot be mismatched.
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 Type and Range” 4 times and then return to
Normal Operation).
3.5.4 Set Gas Factor
Because of the IR sensor’s almost universal response to combustible hydrocarbon gases, the IR-700 sensor can
be configured and calibrated to detect any of the combustible gases listed in the Table 2 and others not shown.
The detected gas is referred to as the “target gas” and the span calibration gas is referred to as the “cal gas”. In
cases where the cal gas is different from the target gas, the Set Gas Factor menu function is used to maintain
accuracy. This feature allows for a significant degree of flexibility in the detection and span calibration
process.
NOTE 1: The default value for Gas Factor is 1.0. This would be used when the target gas is
the same as the cal gas. Values other than 1.0 would be used when the target gas is different
from the cal gas.
NOTE 2: Table 2: Gas Factors can be used for both selections of “gas type = CH4” and “gas
type = HHC-Heavy Hydrocarbons”.
NOTE 3: The “Set Gas Factor” is not applicable for CO
2
versions and should be set to 1.0
NOTE: The gas type and range on the 0-50% LEL range version cannot be changed. When
entering the Set Gas Type & Range menu, the sensor will display “Range is fixed”.