RKI Instruments SDM-E2 - Manual (Page 171)

Obtaining a Relative Response Factor • 166
Power Off Function
This function can be activated by either right clicking an instrument and selecting
Power Off(P) when the pull down menu appears or by selecting an instrument and
then using the alt/P key combination. The Power Off function turns off the selected
instrument. If you select Power Off, a confirmation box appears. Click OK to turn off
the selected unit.
Obtaining a Relative Response Factor
If the gas that you want to monitor on the catalytic combustible or PID channel is not
included in the catalytic or PID relative response lists, you may define up to 5 gases
for the catalytic combustible channel using the Conversion Table tab and 1 gas for the
PID channel using the PID Sensor tab. Testing must be done using the desired target
gas in order to obtain the response factor value for the catalytic combustible channel.
To determine the relative response factor value for the PID channel, first look in
Table 7 for the desired gas. If the desired gas does not appear in the table, you must
obtain the response factor through the testing procedure described below.
To determine the relative response factor value for the catalytic or PID channels, do
the following:
1. For determining the catalytic combustible channel relative response factor,
calibrate the catalytic combustible channel to methane. For determining the
PID channel relative response factor, calibrate the PID channel to isobutylene.
2. Obtain a gas sample of known concentration for the target gas you wish to
define. The sample needs to be at least 10% of the full scale but RKI
Instruments, Inc. recommends using 50% of the full scale. If the concentration
tested results in an overscale reading, test a lower concentration.
3. Apply the gas sample to the EAGLE 2 and take note of the reading. If the gas
sample is of 50 %LEL concentration and the EAGLE 2 display shows a
reading of 25 %LEL, then the factor for that gas is 2. Conversely, if the gas
sample is of 50 %LEL concentration and the EAGLE 2 display shows a
reading of 100 %LEL, then the factor for that gas is 0.5. This conversion factor
value is what you will enter in the Factor column of the gas you are defining.
Table 7 below has 4 columns:
• Gas/VOC-The most common name for the VOC (volatile organic compound)
• CAS No.-Sometimes it is easier to identify a VOC from the internationally
recognized CAS (Chemical Abstracts Service) number
• Formula-Molecular formula for each VOC
• Response Factor (RF)-The relative response factor for each gas. This is the
value that is plugged into the SDM Docking Station PC Controller Program.