3. Make sure the fuel flask is empty and the drain
cock is closed.
4. The falter base and bottle receiver assembly
located in the lid should be disassembled into its two
components. The section with the rubber stopper is the
filter base and should be inserted into the opening in the
fuel flask.
5. The millipore filter is a paper-thin white
membrane. Place two millipore filters right side up on
the filter base. These filters should be handled only with
forceps, and only by their edges. Do not handle the
filters with your fingers. Reassemble the filter base and
bottle receiver assembly. Rotate the locking ring
carefully to prevent damage to the filters.
6. Fill the 32-ounce polyethylene bottle to the 800
milliliter (ml) mark with fuel. Place the filter base and
bottle receiver over the top of the bottle.
7. Make sure that the drain cock valve is closed
or fuel will be pulled out of the drain tank and flood the
machine.
8. Insert the ground wire attached to the filter base
and bottle receiver assembly into the opening provided.
Turn on the pump switch; a vacuum pump is connected
to the fuel flask to speed up filtration.
9. Insert the entire assembly (filter base, bottle
receiver, and fuel sample bottle) into the fuel flask.
During the filtration cycle, the fuel in the sample bottle
should be agitated occasionally by gently shaking the
bottle to ensure that any contaminants are washed down
and not lodged on the inside surface of the bottle. If the
sample bottle tends to collapse, gently loosen the bottle
in the bottle holder by tilting it slightly during the
filtration cycle. After all the fuel has passed through the
filters, stop the pump.
NOTE
Before measuring the contamination on the
filters, you should clean the photocell and light
window.
10. OPEN the drain cock valve and drain the fuel
from the flask through the tygon tubing into a suitable
container. When the flask is empty, CLOSE the drain
cock valve.
11. With the filter out of the receptacle, ensure the
photocell is in the measuring position.
12. Adjust the rheostat knob for a light intensity
reading of 0.6 on the milliammeter.
13. Using forceps, pick up the contaminated filter
top and wet it with clean (refiltered) fuel. Ensure the
entire filter becomes wet with fuel. This prefiltered fuel
is called wetting fuel. It is used to keep the entire
millipore filter wet. It is NOT used to wash
contamination off the millipore filter. By keeping the
entire filter wet you do not get a change of reading from
the dry areas to the wet.
NOTE
WETTING FUEL is produced by rerun-
ning the same sample through millipore filters
several times. Although no exact number of
times is required to rerun the sample to make
wetting fuel, it is recommended that the sample
be rerun until the light transmission readings
for both filters are identical.
14. Lift the photocell (or slide out the plate on
newer machines) and, using forceps, place the contami-
nated filter in the receptacle.
NOTE
The CCFD or DIGITAL reading instru-
ments have a slide plate that you put the filters
on and slide under the photocell. The photocell
does not move. When you use this design, be
careful when putting the filter in the slide and
sliding it under the photocell. If you do not put
the filter in the slide properly, the filter may
come off inside the machine.
15. Swing the photocell (or slide in the plate) back
into measuring position and ensure it is fully seated.
16. Record the reading on the milliammeter; this
reading is in thousandths of a milliamp.
17. Remove the filter. Check to see that the meter
still reads 0.6 milliamps; if not, adjust the meter to 0.6.
18. Repeat steps 13 through 17, using the clean
(bottom) filter.
19. Subtract the meter reading obtained from the
contaminated filter from the meter reading obtained
3-17
