Scott Safety Protege, User Manual

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APPENDIX C: SENSOR INFORMATION
087-0038 REV L SCOTT SAFETY
Sensor K-Factors
Table 19 provides the K-Factors referenced to methane calibration. The factors are the
typical ratios of the response to the listed gases relative to the response to methane.
The values are typical, but will vary from sensor to sensor and over the lifetime of a
given sensor. When a gas other than the calibration gas is detected, divide the reading
by the corresponding factor to estimate the actual gas concentration. For example,
propane may be detected by the device calibrated with methane. If the reading is 32%
LEL: 32% LEL Methane indicated/0.65 = 49% LEL of propane, estimated. Generally,
if there is a potential for methane in the operating environment, the instrument should
be calibrated with methane. If there also is a potential for other gases in the operating
environment, the LEL alarm level should be adjusted according to the lowest
K-Factor of the expected gases. For example, if either methane or propane may be
present, and the desired alarm is 25% LEL, calibrate the instrument with methane and
set the alarm level at (25% x 0.65 = 16% LEL). For best accuracy, calibrate the device
with a gas similar to the monitored target gas.
Table 19 Combustible Sensor K-Factors
KNOWN GAS
PRESENT K-FACTORS
n-Butane 0.6
Methanol 1.04
Ethane 0.8
Hydrogen 1.1
Methane 1
Propane 0.65
n-Pentane 0.5
n-Hexane 0.45
n-Octane 0.4
Ethanol 0.8
Isopropanol 0.69
Acetone 0.7
Ammonia 1.3
Toluene 0.35
Gasoline 0.6
Isobutanol 0.53
Xylene 0.49
Styrene 0.46