Numatic HZ 370-2 Owner's Instructions Manual page 8

Lo - Flo Indicator.
This appliance is fitted with a low flow indicator to show that air flow has reduced.
In the event of the indicator light flashing, check the following:-
Dust caps still fitted
Blocked hose
Cloth filter clogged
Hepa cartridge clogged
Classification
Frequency
Max. Flow Rate (In Product)
Low flow operation
Maximum Underpressure
(NB 16L sec corresponds to an airspeed of 20m/sec in a 32mm pipe)
Cause
Bag full
Voltage
Low Flow Warning Light
Solution
Remove the caps.
Unblock the hose.
Remove and replace
Remove and replace, clean dirty filter by
vacuuming.
Replace, seek advice from an instructed
person or manufacturer.
TYPE H
115V / 220 - 240V
50/60Hz
33L/s (118.8 m3/h)
16L/s (57.6 m3/h)
260 mbar/hPa