TEL AFA4000/E, Инструкция по установке и эксплуатации

Страница: 50 / 210

AFA4000/E VAV Airflow Controller / p.50
sensor. This will lead to too much sensitivity being required to calibrate the unit which can
lead to instability of the readings or incorrect readings at low velocities.
3. For fume cupboards with a single-skin side-wall, or 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 it using a short flexible tube to a rigid wall tube attached to the inner side-wall.
Position the open end of this rigid wall tube in the ‘ideal position’ for example, 100 mm back
from the sash, and 100 mm higher than the normal sash opening.
Fume cupboards with a large internal height can present a difficulty because the tube length
to reach the ideal position may be longer than 1m. Where possible, use a tube of 1 metre or
less, 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 where it is subject to draughts from the
laboratory air input or ventilation system.
5.2 Installation
5.2.1 AFA4000/E
1. Use the cut-out details provided with the unit (Figure 16) to cut out and drill the holes in the
fume cupboard for the AFA4000/E mounting bracket.
Make sure that the AFA4000 fits into the cut-out before proceeding.