Document Ref 942005-001 Rev 2
Page 4-3
Component Technical Manual
TQP-HS for Fuel Dispensers
4.2
Inlet Pressure
The inlet pressure can be measured using a special filter box cover (refer to section 5.3 for
specific tools) and a pressure gauge with range -1 bar up to 3 bar.
At full flow (i.e. two nozzles at 40 l/min), the inlet pressure measured is the pressure loss
caused by the resistance of the site configuration (i.e. the height of pump in comparison to
the storage tank and the length of the pipework).
If the inlet pressure is too high, check the following:-
• Condition of the filter. Clean and/or replace as required.
•
Operation of the foot valve. Repair or replace as required.
•
Installation pipework back to the storage tank i.e. operation of the non-return valve, dirt
blocking the flow, tank filter clogged etc. Repair and/or replace as required.
Re-check the inlet pressure and repeat the above procedures until a satisfactory
measurement is obtained.
4.3
Air Vent
Place one end of a tube (inner diameter 12mm) with a
3
/
8
" BSP thread coupling on the vent
and drop the other end of the tube into a small container with fuel (same fuel as storage
tank).
Start the pump in by-pass mode by lifting the nozzle from its holder and letting it run for a
while before opening the nozzle. Check for the following:-
•
Bubbles appearing constantly - this means that there is an air entry in the pump or the
installation before the pump.
•
Fuel is being sucked into the pump - this means the recovery float valve is not closing
properly.
NOTE
If the vent is difficult to reach
, t
ry to feel with your hand if a stream of air or vapour
is expelled from the vent.
Put the tube in the tank (not
too deep), and observe if
there are bubbles.
