FREE WATER DETECTOR (AEL MK I AND AEL MK II)

e. Now draw a line connecting the two. f. Date the calibration chart so as not to confuse it with the previous chart. NOTE On the back of the chart it is a good practice to put the serial number of the Wratten filters used and on the front it is required to have the machine serial number. FREE WATER DETECTOR (AEL MK I AND AEL MK II) The free water detector (fig. 3-8) was developed to measure accurately the amount of free water in fuels. This detector is used with the Contaminated Fuel De- tector in the normal fuel inspection and surveillance programs; the test should be executed as soon as possi- ble following the sampling. The free water detector consists of an ultraviolet light source, a set of standards indicating 0, 5, 10, and 20 ppm, and water detector pads. A test sample of fuel is passed through a chemically treated filter pad in the filter holder of the Mk III detector. The chemical on the pad is sensitive to any free water in the fuel. If water is in the fuel, the pad produces a visible fluorescent pattern when it is placed under an ultraviolet light. Instructions for using the AEL free water detector are as follows: 1. Mark the polyethylene bottle 3 1/4 inches from the bottom. When the bottle is filled to this mark, a 500-ml sample will be obtained. 2. Fill the polyethylene sample bottle to the 500- ml mark with fuel to be tested. 3. Open a free water detector envelope and place the detector pad, orange side up, on the contaminated fuel detector base. Attach the bottle receiver to the filter base and plug in the ground wire jack. CAUTION Handle the detector pad with forceps only. Do not touch the pad with your fingers or it becomes contaminated before you even start the test. 4. Check to see that the contaminated fuel detec- tor fuel flask is empty and the drain cock closed. 5. Shake the bottle containing the 500-ml fuel sample vigorously for approximately 30 seconds. 6. Immediately after shaking, turn the vacuum pump on, unscrew the bottle cap, place the bottle re- ceiver firmly over the end of the bottle, and insert the filter over the end of the bottle. Then insert the filter base into the contaminated fuel detector. This step should be done in as short a time as possible to keep any free water in suspension. 7. After the 500-ml sample has passed through the detector pad, turn off the vacuum pump IMMEDI- ATELY, and remove the bottle and bottle receiver. NOTE DO NOT continue to draw air through the detector pad. If the moisture in the air is drawn through the pad, you get an incorrect reading. 8. Remove the pad from the filter base with for- ceps and place it (orange side up) in the free water detector slide depression. 9. Light the ultraviolet bulb in the free water detector by holding the light switch in the ON position, and insert the slide containing the test pad. 10. Look through the view port of the box and compare the brightness of the test pad with that of the set of standards to determine the amount of free water. Free water content is indicated in ppm by the numbers located directly above the standards. 11. If the result is over 20 ppm, take a new sample of one-half the standard sample and double the answer. NOTE The standards card in the free water detec- tor must be replaced after 6 months of use according to PMS. The standards in the box when received should be marked with the date on which the detector is first put into use. The reason for replacing the standards every 6 months is that the fluorescent inks in the pads deteriorate after prolonged exposure to ultra- violet light. To replace the ultraviolet bulb, turn the used bulb one-quarter turn and lift it out of the fluorescent lamp 3-20