TEL AFA1000/2 MK2, Installation & Operating Manual

Page: 38 / 53

Version 01 / p.38
AFA1000/2 MK2 Airflow Monitor
Installation & Operating Manual
6.4 Calibration Notes
1. When using a standard Fume Cupboard with Vertical Sliding sashes open the sash to the
normal max safe working height for the Low Air sample.
2. For the Higher Air sample close the sash to approx 50% of the opening used for the Lower
Air sample. If the Higher air sample value is too close to the Lower Air sample the alarm will
detect this and ask you to repeat with a higher value.( The minimum difference between the
Low & High air samples is set to 0.3 m/sec )To do this close the sash a little more and repeat
the sample. Avoid closing the sash below 150mm.
3. The face velocity readings on the open sash may vary at different points on the measuring
grid by up to 0.1 m/sec. This is quite acceptable in terms of the fume cupboard performance
so long as no individual point is below the designated Low Air alarm point .The figure entered
for the calibration point can be taken as the average value of all the measuring grid readings
or could be taken as the individual lowest point on the grid. For most fume cupboards this
low point is on the bottom row in the centre and is a convenient position to measure and for
future reference when checking the alarm during annual maintenance.
4. Take time when measuring the face velocities for the calibration procedure to allow for the
velocities across the open sash to stabilize. If the velocities are changing or are turbulent
during the sampling period the alarm will detect this and ask you to repeat the sample.
5. When using a Fume Cupboard with Horizontal Sliding sashes open the sashes to the normal
max safe working opening for the Low Air sample.
6. When calibrating or re-calibrating the alarm it is important to ensure that the ‘Vent kit’ is
connected to the SM6 sensor on the fume cupboard. If the vent kit is not connected the
sensor will not ‘see’ a change in the airflow during the calibration procedure and will show
“Sensor Difference too low - Check sensor”. This only applies during the calibration mode. If
in normal running after successful calibration the vent kit becomes disconnected the air flow
across the sensor will fall and the alarm will go into the AIR FAIL condition.
If the airflow display is unstable following the calibration due to environmental turbulence or sensor
position and cannot be rectified then it is possible to adjust the sensitivity of the displayed value
using the Display Smoothing parameter in the cal config menu. The monitor will display the velocity
value as a rolling average over time and is adjustable over 1 to 100 seconds.