RKI Instruments 35-3000RKA-10 - Manual (Page 23)

35-3000RK-10 PPM Hexane Sample Draw Detector • 23
22. Wait 1 to 2 minutes to allow the combustible gas reading to decrease and stabilize.
23. Re-install the amplifier using the screws, flat washers, and lock washers removed in
Step 4 above.
24. Calibrate the sample draw detector as described in “Calibration” on page 23
25. Verify that the controller display reading decreases and stabilizes at 0 ppm.
26. Store the components of the calibration kit in a safe and convenient place.
Calibration Frequency
Although there is no particular calibration frequency that is correct for all sample draw
detector applications, a calibration frequency of every 6 to 12 months is adequate for most
applications. Unless experience in a particular application dictates otherwise, RKI
Instruments, Inc. recommends a calibration frequency of every 6 months.
If an application is not very demanding, for example detection in a clean, temperature
controlled environment where hexane or other combustible gasses are not normally
present and calibration adjustments are minimal at calibration, then a calibration
frequency of every 12 months is adequate.
If an application is very demanding, for example if hexane or other combustible gasses are
present often and in significant concentrations or the environment is not well controlled,
then more frequent calibration than every 6 months may be necessary.
Calibration
This section describes how to calibrate the sample draw detector. It includes procedures to
assemble the calibration kit, set the zero reading, set the response reading, and return to
normal operation.
NOTE: The following procedure assumes the use of a calibration kit that includes a
calibration gas cylinder, a dispensing valve with an on/off knob, a gas bag, and a
humidifier tube to connect the gas bag to the dispensing valve and to the sample
draw detector inlet line. A demand flow regulator calibration kit is also available.
Calibration Kit Humidifier Tube
The sample draw detector requires normal atmospheric humidity levels to respond
properly to hexane because of the low ppm levels involved. Normal atmospheric
humidity variations do not affect the detector’s response to hexane in ambient air, but the
ultra low humidity level of gas from a calibration cylinder requires that the calibration
sample be humidified for the detector to respond properly. The calibration kit for the
sample draw detector includes a humidifier tube with flexible polyurethane on each end
that is not normally included in other calibration kits. This humidifier tube humidifies the
calibration sample flowing through it by absorbing humidity from the ambient air and
adding it to the sample. The humidifier tube is included in Table 2 on page 26.
WARNING: A humidifier tube must be used when calibrating the sample draw detector
for the detector to respond properly to the calibration gas. Failure to use a
humidifier tube will result in an inaccurate calibration.