If a sludge problem persists, fuel testing/treatment and tank cleaning/replacement should be considered.
unit, connect a push-pull pump to draw fuel
through the line until clean fuel flows freely
between the filter and the fuel unit.
4. Clean or replace the pump strainer,
completely remove the existing fuel unit cover
gasket and install the correct new gasket.
5. Reconnect the fuel line and bleed air
from the fuel unit.
6. Check the running vacuum. Compare
the reading to the expected operating vacuum
calculated using the following formula:
• 1" for every foot of vertical lift
• 1" for every ten feet of horizontal run
• 1" for the filter
• 2"- 4" for an OSV valve
If the reading exceeds calculated vacuum,
there may be a restriction in the line. Inspect
the exposed line to see whether it has been
damaged, kinked or crushed. If a defect is
found, replace the line. Never attempt to repair
a damaged fuel line. If the line appears to be in
good condition, try using the push-pull pump
again and re-check running vacuum after clearing
the obstruction.
If the unit is part of a two-pipe system, consider
converting it to a one-pipe system. Doing
so will reduce the amount of fuel being filtered
by over 90%. This can reduce the need for
filter replacement. When converting a fuel unit
to one-pipe operation, be sure to remove the
bypass plug if the pump has one and consider
installing a fuel de-aerator.
44 National Oilheat Research Alliance
For an installation that is operating on a one
pipe system—if the filter needs replacement
more than twice a year, a more permanent remedy
may warrant consideration.
Filter clogging may be a symptom of bacteria
in the fuel which can cause microbiologically
induced corrosion. If the sludge problem
persists after the tank has been cleaned, the fuel
should be tested and treated as needed. Options
include initiating a designed fuel treatment
program and tank replacement.
B. Out of Fuel Guide
When an automatic delivery customer’s tank
is out of fuel, it is extremely important to
determine why the tank is empty before
making a delivery.
First, the technician
should measure
the tank to determine
that it actually
is “dry.” Knocking
on the side of the
tank doesn’t work;
get out the measuring
stick and make
sure!
Once it is established
the tank is
empty, office personnel should research when
the tank was last filled and determine if it was
currently due for delivery.