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Air pressure switch
This is used to check whether the fumes are adequately evacuated. The pressure switch compares the static
and dynamic signals coming from the pressure test points on the fan according to the figure. The pressure
switch is connected to the card and is normally open (see diagram). Before the card initiates the ignition
procedure (opening the valve, etc.), you must make sure that the fan works properly and that the air pressure
switch ensures this by closing its contacts. This happens if the difference in pressure is 165±15Pa. So the
signal must be at least 180Pa. To open its contacts again, the difference in pressure must drop under
150±13Pa. To perform checks on contact opening and closing, it is always recommended to check directly
on the card (X5 - 3/4).
Checks
It is necessary to check:
•
Whether the electrical connections are correct.
•
Whether the pressure test point pipes are clean and contain no condensation water.
•
That the signal is open when the fan is not working.
•
That the pressure is at least 180Pa and that above this pressure the pressure switch closes its contacts.
•
If the signal is low, it is necessary to check that the fume diaphragm is correct, the fan has 230V, the
pressure test points are properly inserted and the Venturi tube has no burrs of any kind. Lastly, check
that the ends of the pipes are not obstructed.
N.B. The pressure difference must be measured with the airtight chamber closed. The pressure gauge
connections can come out through the hole, which is closed by a silicone plug, on the front of the cover.
24
DOMITOP HF 24 - 30 E
FERELLA GOLD HF 24 - 30 MEL
Pressure gauge
pa
C
Key
NO = Normally open
NC = Closed
C
= Common
Version - 09.2002
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