Calibration – RKI Instruments 65-2340RKSS User Manual
Page 18
14 • 65-2340RKSS Toxic Gas Transmitter
Calibration
This section describes how to calibrate the toxic gas transmitter. It includes procedures to
prepare for calibration, set the zero (fresh air) reading, set the span (response) reading,
and return to normal operation. It describes calibration using a calibration kit that
includes a calibration cup, calibration gas, sample tubing, and a fixed flow regulator with
an on/off knob. The required sample flow rate and calibration cup depend on the
transmitter being calibrated. Table 3 below lists the required calibration cups and
regulators for the various toxic gas transmitters.
WARNING: Not using the recommended calibration cup, sample flowrate, and specified
flow direction (for 81-1138RK calibration cup only) will result in an
inaccurate calibration. Make sure to use the calibration cup and sample
flow rate listed in Table 3 for your target gas when performing a
calibration. Also make sure to connect the sample tubing to the calibration
cup port that results in the specified flow direction for the 81-1138RK
calibration cup.
Preparing for Calibration
1.
Place the controller into its calibration mode or disable external alarms.
2.
Unscrew and remove the junction box cover.
3.
Set a voltmeter to measure in the millivolt (mV) range.
4.
Plug the voltmeter leads into the test points on the amplifier. Plug the positive lead
into the red + test point; plug the negative lead into the black - test point.
5.
Use the following formula to determine the correct test points output for the
calibrating sample.
Output (mV) = (calibrating sample/fullscale) X 400 + 100
Table 3: Required Calibration Cups and Flow Rates
Transmitter Type
Required
Calibration Cup
Required Regulator/
Flowrate for Calibration
Gas
Flow Direction
Specified on
Calibration Cup
Arsine (AsH
3
)
81-1138RK
81-1051RK, 0.5 LPM (liters
per minute)
Yes
Chlorine (Cl
2
), 0 - 3.00 ppm
and 0 - 10.0 ppm
81-1138RK-CL2
81-1051RK, 0.5 LPM
No
Hydrogen Cyanide (HCN)
81-1138RK-HCN
81-1051RK, 0.5 LPM
Yes
Ammonia (NH
3
)
81-1138RK-NH3
81-1051RK-25, 0.25 LPM
No
Phosphine (PH
3
)
81-1138RK
81-1051RK, 0.5 LPM
Yes
Sulphur Dioxide (SO
2
)
81-1138RK
81-1051RK, 0.5 LPM
Yes