(e) Adjust the lever on the back of the
unit until the meter reads zero when the switch button on the meter
4. Interpreting test results. The scale reads
in parts per million where the lever crosses it if the test sample is
500 ml. The scale multiplying factor is 5 if a 100-ml test sample is
used. The scale is calibrated for a fuel-damp test pad. Divide the
scale reading by 1.2 if the test pad is read when it is not fuel
damp, and if the water content is in the range of 1 to 8 ppm. A
factor of 1.3 should be used if the water content is more than 8 ppm
when the pad is dry.
5. Storing exposed pads. Exposed pads can be
stored for long periods if kept in desiccant-dried containers.
change appreciably in open containers or envelopes.
The vast majority of readings that are taken on
aviation fuels do not indicate the presence of any
free water. If the technician wishes to reassure
himself that the detector pad is effective and the
instrument is functioning, he can moisten his
finger, touch it to the pad and view the pad in
6. Scale conversion chart. The water detector
unit can be used to take undissolved or "free" water content readings
regardless of the quality of fuel that has passed through the detec-
tor pad. Figure 2-12 gives the conversion from scale readings to
water content for different sample volumes from 100 to 500 ml. The
figure can be used to obtain scale multiplying factors for any sample
volume, even if that volume is not an exact 100 ml increment. The
unit can also be used to read water content when detector pads are of
a different size than the ones that are supplied with the unit. The
standard detector pad is 25 mm in diameter, but other pads are made
that have a diameter of 37 and 47 mm. Be sure to use only 25 mm
The Aqua-Glo calibration may not be accurate if
additives are present. For example, certain
additives used in heating oils will prevent
water that is not dissolved in the fuel from
reacting with the sodium fluorescein.
25 mm test pads.
(b) Example: A scale reading of 6 is re-
corded on a fuel damp, 25 mm test pad. The sample volume was 100 ml.
Read up from the scale reading of 6 to 100 ml curve. Then read on
the left-hand scale 30 ppm water content. Refer to TM 5-6630-216-12
for complete instructions covering the Water Detector Kit, Automotive