Nilfisk-Advance America GB 1133 - Manual (Page 10)

9 Adjusting the automatic gear change of the minimum airflow
Use the performance profile to adjust the cutoff point for the minimum
airflow of extractors. First of all, find out the minimal airflow that ensures
a good operation of the dust-producing system. Mark this value on the x-
axis, then draw a vertical line from here to the curve. Now draw a line
parallel to the x-axis from the point of intersection to the y-axis. This
value describes the vacuum that has to be adjusted at the vacuum
switch when the minimal airflow is no longer sufficient.
When adjusting the vacuum, you have to connect an appropriate
measuring device parallel to the vacuum switch. Throttle the airflow at
the suction inlet until the required value is reached. Now calibrate the
cutoff point by the adjusting screw of the vacuum switch.
When the minimal airflow falls short, the following happens after a few
seconds:
- the red warning light flashes up.
- the floating contact in the switch housing switches. This contact (6 A at
a
voltage of 230 V, AC11) manages the connection of the control circuit
of
the dust-producing system to the extractor or to control an external
optical or acoustical signal.