Labconco Guardian 1000 Digital Airflow Monitor User Manual
Page 11
11
2.2 Calibration Notes :-
1.
When using a standard Fume Hoods 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. To do this close the sash
a little more and repeat the sample. Avoid closing the sash below 100mm.
3.
The face velocity readings on the open sash may vary at different points on the
measuring grid by up to 20fpm. 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 stabilise. 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 Hood 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 hood. If the vent kit is not connected the
sensor will not ‘see’ a change in the airflow during the calibration procedure and when
switched to the Run condition the display will show a fixed reading that will not change
when the fume cupboard velocity changes.
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.