4.1
SECTION 4 INSTALLATION – GAS CONNECTIONS
4.1 Introduction
Sample and calibration gases pass into and out of the chassis via a gland plate mounted on
the rear of the chassis. The sample gland plate with or without external autocalibration provides
up to four sample inlets and a corresponding outlet for each inlet, and an optional interface
connector, PL 8. When optional internal paramagnetic autocalibration solenoid valves are used
a manifold is mounted on the sample gland plate which provides ports for sample inlet and
outlet, and inlets for low and high calibration gases for gas sensor module 1 only.
4.2 Calibration gases
The gas mixtures recommended for calibration of the instrument will depend on the gas
components measured by the transducers fitted to the gas stream and the measurement
ranges of the transducers. The recommended gases are limited by the long term storage
stability of the components of the mixture. Certain gas mixtures should be avoided as these will
not be stable with time. For example gas mixtures containing (all of the following) O
2
and NO
are not stable and should not be used.
Note, the 4900 analyser permits several sensors to be on a single sample stream. In such
cases the selection of calibration gases for use with either internal or simultaneous external
autocalibration will either have to facilitate the requirements of several transducers at the same
time or be controlled by their own relay/solenoid. Examples of calibration gases (particularly for
use with Gfx arrangements) are shown in Table 4.1, below.
CAUTION
• The condition of the gases supplied to the analyser depend on the analyser
configuration. Full details are given in Section 7.
• Failure to comply with the specifications will result in damage to the
analyser.
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