GE XDP-H2, User Manual

Page: 49 / 96

January 2008
4-20 Setup and Calibration
Calibrating the System
Prior to shipment, the XDP/transmitter system is factory-calibrated
for the range(s) and gas mixture(s) specified at the time of purchase.
However, to ensure the accuracy of the readings, the system should be
recalibrated every 2–6 months. The optimum calibration interval
depends on the specific details of the application and is best
determined by periodic calibration checks after the initial installation.
Caution!
The calibration procedures described below should only
be performed by trained service personnel.
In order to complete the calibration procedure, the following items
are required:
•
zero gas (usually either 100% air or 100% carbon dioxide)
•
span gas (usually 100% hydrogen)
•
a suitable sample system
IMPORTANT:
Each gas cylinder must be certified as to the exact
composition of the gas. The accuracy of the
calibration is only as good as the accuracy of the
calibration gases used.
Proceed with the instructions in this section to calibrate the system.
Initial Preparation
A temporary connection between the transmitter and the gas cylinder
may be made for calibration purposes. However, if a permanent
connection is preferred, it should be as short as possible, with an
isolation valve right at the gas inlet port on the transmitter (see the
transmitter and/or sample manual for details).
!WARNING!
When working in a hazardous area, carefully follow all
appropriate safety guidelines during the calibration
process.
To set up for calibration complete the following steps:
1.
Turn the system power ON and allow at least 30 minutes for the
sensor to reach temperature equilibrium.
2.
Begin the flow of the zero gas to the inlet port of the transmitter, at
about 250 cc/min (0.5 SCFH) and atmospheric pressure.