100mm
100mm
No rm al Sash
work in g he ig ht.
eg . 500m m
670
670 Face
laboratory
25mm
Female adapter
Fume cupboard
outer skin
Fume cupboard
inner skin
25mm
Male
bush
25mm Tube
4.0 Fume Hood Installation
It is very important to position the Series 670 airow 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 Series 670 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 hood. (This tube and ttings is known as the “vent kit”). The ideal position for the end of the 25mm tube
for most fume hoods 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 hood and use a short length of tube. Tube lengths of more
than 1 meter or smaller diameter will restrict the airow 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 hoods 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 exible tube. With a single skin side wall it is possible to x the sensor
on the outside of the fume hood and connect directly to the inner chamber in the ideal position. This method can
only be used for up to two fume hoods 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 hood and connect using a short exible 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’, i.e., 100mm back from the sash and 100mm higher than the normal sash opening. Fume hoods
with a high internal height can present a difculty because the tube length to reach the ideal position may be longer
than 1 meter. In this case it is better to use a tube no longer than 1 meter which may result in a sensing position
higher than the ideal. When tting a sensor to a ’narrow wall’ fume hood for the rst time it may be necessary to try
various combinations of rigid and exible tube to nd the best combination and position.
4. The sensor should not be mounted in a position were it is subject to drafts from the laboratory air input or ventilation
system.
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