Page 4-4
Document Ref 942005-001 Rev 2
TQP-HS for Fuel Dispensers
Component Technical Manual
4.4
Internal Air Entry in the Pump
Possible causes for air to enter the pump are as follows:-
•
The filter cover O-ring is incorrectly positioned or dilated.
•
The O-ring between the filter box and the pump body is incorrectly positioned or dilated.
•
One of the sealing rings between the connection to ground piping and filter box is defective
or insufficiently tightened.
•
The float assembly is blocked in an open position, incorrectly installed or contains loose
particles in between.
4.5
External Problems up-stream the TQP-HS
To test for problems up-stream the TQP-HS pumping unit:-
•
Check the operation of a non-return valve (where fitted). If the valve is defective (if
mounted according to dispenser model), replace the valve.
•
Check for a blockage in the volume meter. If the meter is blocked, replace the volume
meter.
•
Check the condition of the nozzle filter and nozzle. If the nozzle filter is clogged, clean or
replace the filter as required.
•
Check the operation of the electronic valve. If the valve is blocked, replace the electronic
valve.
4.6
Excessive Head Loss
When the ambient temperature increases, the ability to pump fuel is reduced due to the
formation of vapour locks. Check if the pipework and manifold are sufficiently insulated
(as installed) from ambient heat sources.
To reduce the temperature build-up, the manhole chimneys can be filled with sand and the
manhole covers can be painted white.
If a satisfactory technical solution cannot be found, try to maintain normal operation by
keeping the storage tank filled as much as possible as this will reduce problems coming
from high ambient temperatures.
To test for problems with excessive head loss:-
1)
Check the head loss resulting from the specific configuration of each fuel line by comparing
the measured head loss under each dispenser at the point where the same fuel from the
same underground storage tank arrives.
•
If these various measured head loss values are comparable:-
- Check the expected (theoretical) head loss values are indeed comparable to those
measured. If not, then the fuel line may be obstructed by an unknown object.
•
If these various measured head loss values are not comparable:-
- Check the connection between each pump and the relevant underground pipework
(e.g. manifold, non-return valve blocked).
