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3654 Portable H2/N2 Analyzer - Installation 11 of 66
Operator Manual
ORBISPHERE
1.5 Purge Gas Connection
It is critical that the TC sensor has a supply of purge gas running before operating the
system. The TC sensor, when exposed to a liquid sample, will become damaged if the
purge gas is not running.
CO
2
is used to purge the N
2
sensor and N
2
or CO
2
is used to purge the H
2
sensor. A
cylinder located at the bottom of the instrument supplies the purge gas. This cylinder is
refillable (see “Purge Gas Cylinder Refill” on page 48).
The TC sensor is purged cyclically. In measurement mode, a cycle consists of a 4
second purge followed by 16 seconds of measurement. When the instrument is in
standby, the purge time is the same, followed by a 17 minute delay. During the purge
time, the flow rate varies, depending on the pressure inside the cylinder. At least four
bubbles should exit from the purge gas exit during the purge time.
The purge gas input to the sensor uses a Tygon tube (4 mm outside/2 mm inside
diameter, 110 mm long) that attaches to the base of the sensor. Refer to the exploded
sensor diagram in Fig 1-2 on page 10.
The hole in the side and near the base of the sensor is the purge gas exit. To check the
purge gas flow rate, push the supplied nylon tubing into this hole, to its limit. To
disconnect it again, press on the ring surrounding the tube and pull out.
To check the purge gas flow rate, immerse the end of this tubing in water and switch on
the instrument. Gas should flow intermittently out of the tube.
Note:
During normal operation, and especially when the instrument is in standby mode,
ensure that the exit of the purge gas tube is exposed to the atmosphere and not in
contact with any liquid or hard surface.
1.6 Connections
1.6.1 External Power Supply (optional)
The instrument is usually powered by the batteries supplied. You can, however, power it
from an external power source using the model 32939 power supply adaptor as
described and illustrated in “Model 32939 External Power Supply” on page 42.
Connect the male LEMO-6 plug on the 32939, to the RS-232 connector on the right side
of the instrument. The female LEMO-6 plug can then be used to connect to your PC (if
required) using the standard RS-232 cable supplied with the instrument.
Plug the transformer into your mains power supply using the cable supplied.
Note:
If the external power supply is not clean, this may result in unstable measurements.
1.6.2 Instrument - PC Connection
An RS-232 cable is supplied with the instrument, with a 6-pin LEMO plug on one end and
a 9-pin D-Type plug on the other.
Note:
If you use an adapter for the connection to the PC, make sure it is designed for this
purpose and, thus, has all nine pins accessible. Some 25-to-9 pin adapters are supplied
for specific use, such as a mouse, and these may have only certain pins available.