Interpreting test results

TM 5-6640-213-14

(e) Adjust the lever on the back of the

unit until the meter reads zero when the switch button on the meter

is depressed.

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.

They

change appreciably in open containers or envelopes.

NOTE

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

the-instrument.

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

pads.

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.

(a) Condition:

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

Aviation Fuel.

2-32