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3.2 Mounting the Enclosure
The
mini
CHEM
-DO
2
can be wall-mounted with 3 screws. Two mounting points
are located underneath the terminal cover, and are positioned so that they do not
affect the waterproofing of the enclosure. The third mounting point is centrally
located near the top of the rear of the enclosure, and has been designed to hook
over a screw-head. The dimensions for the mounting screw centres are provided on
the rear of the enclosure. The last page of this manual may be photocopied or
removed for use as a drilling template.
3.3 Mounting the Sensors
Mounting the sensor is a very important aspect of the installation, and is often done
incorrectly. In automatic control situations, the sensor should always be mounted
as close as possible to the injection point. This will cause the sensor to detect the
added oxygen or chemicals immediately, and shut the addition off until mixing has
taken place. For in-line mounting, it is important that oxygen or chemicals are
injected upstream. Additionally, the line must be run through a mixing chamber,
such as a large drum, to ensure that the injected oxygen or chemical has mixed in
properly by the time the solution flows past the sensor. There must always be
adequate flow of fresh sample past the sensor, for accurate monitoring. The
diagrams below show typical mounting arrangements for “dip” mounting and in-
line mounting.
Dip Mounting
1. Injection point close to sensor.
2. Continuous stirring.
In-line Mounting
1. Injection point upstream from and
close to sensor.
2. Mixing container after injection and
before sensor.
3. DO
2
sensor mounted as close to
vertical as practical, through a
suitable gland fitting.
