TEL AFA1000/2 MK2, Installation & Operating Manual

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Version 01 / p.34
AFA1000/2 MK2 Airflow Monitor
Installation & Operating Manual
5.4 SM6 Airflow sensor installation
It is very important to position the SM6
airflow sensor in the correct position to
give long term stable reading of the face
velocity. Please read the INSTALLATION
NOTES below and if in doubt contact us
for further advice.
INSTALLATION NOTES :-
1. The SM6 sensor must be positioned
where it can “ see “ the room pressure of the
laboratory.The back connection spigot of the
sensor is designed to accept a 25mm OD
tube which should be connected to the inner
chamber of the fume cupboard. (This tube
and fittings is known as the “ vent kit “ ) The
ideal position for the end of the 25mm tube
for most fume cupboards is 100mm back
from the sash glass and 100mm higher than
the normal sash opening height through the
inner side wall.
2. If possible mount the sensor on the front
of the fume cupboard and use a short length
of tube. Tube lengths of more than 1M or
smaller diameter will restrict the airflow
through the sensor. This will lead to too
much sensitivity being required to calibrate
the unit which can lead to some instability
of the reading or incorrect readings at low
velocities..
3. For fume cupboards with a single skin
side wall or a double skin with a small gap
between them it may not be possible to
achieve the ideal sensing position using a
flexible tube. With a single skin side wall it
is possible to fix the sensor on the outside
of the fume cupboard and connect directly
to the inner chamber in the ideal position.
This method can only be used for up to two
fume cupboards when they are positioned
side by side ( using the two outer walls ) An
alternative method is to mount the sensor on
the front of the fume cupboard and connect
using a short flexible tube to a rigid wall tube
attached to the inner side wall. The open end
of this rigid wall tube should be positioned
in the ‘ideal position’ ie. 100mm back from
the sash and 100mm higher than the normal
sash opening. Fume cupboards with a
high internal height can present a difficulty
because the tube length to reach the ideal
position may be longer than 1M. In this case
it is better to use a tube no longer than
1M which may result in a sensing position
higher than the ideal. When fitting a sensor
to a ’narrow wall’ fume cupboard for the
first time it may be necessary to try various
combinations of rigid and flexible tube to find
the best combination and position.
4. The sensor should not be mounted in a
position were it is subject to draughts from
the laboratory air input or ventilation system.