ASTM D7224 Standard Test Method for Determining Water Separation Characteristics of Kerosine-Type Aviation Turbine Fuels Containing Additives by Portable Separometer
10. Sampling and Sample Preparation
10.1 Special precautions concerning sampling technique and sample containers are described in Appendix X2. Extreme care and cleanliness are required in taking samples either directly into the test syringe or into a sample container. Before pouring the test specimen from the container, wipe the container outlet thoroughly with a clean, lintless wiper; pour the test specimen into a clean beaker or directly into the barrel of the test syringe.
10.1.1 Test method results are known to be sensitive to trace contamination from sampling containers. Refer to Practice D4306 for recommended sampling containers.
10.2 Under no circumstances shall a sample be pre-filtered, because filter media can remove the very materials, surfactants, that the test method is designed to detect.
10.2.1 Haze in a sample can be indicative of free water, which can result in MSEP ratings in excess of 100.
10.2.2 If the sample is contaminated with particulate matter or haze, allow such materials to settle out of the sample before testing.
10.2.3 If a sample does not clear up after being allowed to stand for a period of time, the sample cannot be tested by this test method.
10.3 If the sample is not within the test temperature limits, 18 °C to 29 °C (65 °F to 85 °F), allow the sample to stand or place the sample container in a water bath until the temperature is within the prescribed limits. The preferred temperature for testing is approximately 27 °C (80 °F).
11. Preparation of Apparatus
11.1 Locate the instrument on a clean workbench in an area where the temperature is between 18 °C and 29 °C (65 °F and 85 °F) and does not vary more than +/- 3 °C (5 °F).
11.2 Open the case and remove the power cord and test accessories from the lid. Raise the right panel until completely vertical and locked in place. If ac power is available, connect the power cord, and turn the instrument on. If the internal battery power is used, ensure that the batteries are charged sufficiently to perform the desired number of tests. Low battery power is indicated when the power lamp does not illuminate. To recharge the battery, connect the instrument to an ac power source for at least 16 h (full charge) prior to use. Depending on the age of the battery, approximately 25 tests can then be performed.
NOTE 6 - If the battery in the Mark X is not charged sufficiently to run a test, an ERR-06 will be displayed indicating that the battery must be recharged.
11.2.1 Turn the Mark V Deluxe and Mark X instruments on by depressing the switch (push-button) marked ON. The ON power indicator light will alternately pulse on and off when the instrument is connected to an ac power source and will stay on continuously when operated by the battery pack. Flickering of the power indicator light, during any portion of a test sequence being performed using battery power, indicates that recharging is necessary.
11.3 Have ready a supply of vials, MCell Coalescers, plastic syringes with plungers, syringe plugs, pipet tips, as well as a clean container of double-distilled water. All of these expendable items are furnished in each six-pack. Also have the pipet that is furnished with each Micro-Separometer instrument readily available. If the aluminum syringe and plunger are being used instead of the plastic syringe, have a plastic connector available as well.
11.3.1 Under most circumstances, either the plastic syringe or the aluminum syringe may be used. Research and round robin studies during the development of this test method demonstrated that aluminum and plastic syringes had equivalent precision. Under very dry ambient conditions (when electrostatic charges can readily develop in the plastic syringe, giving erroneously high results), or in case of dispute, use the aluminum syringe.
11.4 Syringe drive travel times during the coalescing test period were initially calibrated at the factory for each mode of operation and have a significant bearing on the final test results.
11.4.1 The acceptable drive travel time range for Mode A operation is 45 s +/- 2 s.
NOTE 7 - Slow syringe drive travel times exceeding the upper limit (47 s) will cause the final results to measure high; conversely, fast travel times below the lower limit (43 s) will cause the final results to measure low.
11.4.2 Both the Mark V Deluxe and Mark X instruments have self-check circuitry to detect out-of-tolerance syringe drive travel times. The alert indicator lamp (marked SYR) illuminates and depending on the degree (more than 3 s) of the out-of-tolerance condition, three short (1 s) tones will also sound.
11.4.2.1 An occasional out-of-tolerance alert may be experienced due to some intermittent condition that probably will not be indicative of instrument failure. To verify that an alert is only an intermittent condition, time the syringe travel from when the syringe drive begins down to when it stops. This must be performed during an actual test so that proper back-pressure is present. Repeated alerts are cause for returning the instrument to the factory for adjustment.
11.4.2.2 Mark X - During a test, the error alert indicator will illuminate and ERR-03 will be displayed indicating an out of tolerance syringe travel time. Error alerts ERR-01 and ERR-02 will be displayed if the syringe stalls while traveling up or down, respectively.
12. Calibration and Verification
12.1 The instrument is calibrated at the factory by using in-house test fixtures.
12.2 Instrument performance, especially for field use, may be verified by performing MSEP tests using a dilution of the dispersing agent (as prepared in 8.3), a reference fluid base (as prepared in Appendix X1), and double-distilled water. A 10:1 dilution is prepared by diluting 10 mL of dispersing agent with 90 mL of toluene (8.2). Since 1 mL of dilution is equal to 0.1 mL of dispersing agent, 50 mL of dilution is equal to 0.1 mL/L when added to 50 mL of reference fluid base. The 0.1 mL/L of dispersing agent corresponds to even multiples of the concentration levels listed in Table 2. This facilitates using the 50 mL pipet (7.4.6) to add increments of 0.1 mL/L of dispersing agent, as well as the double-distilled water required for the MSEP test. Depending on the type of reference fluid base, the MSEP ratings are compared to the values listed in the applicable table for the particular concentration of dispersing agent used.
12.3 If the results do not fall within the range of limits shown in Table 2, the reference fluid shall be discarded, a fresh quantity of reference fluid prepared, and the check repeated. Repeated out of tolerance test results are cause for returning the instrument to the factory for adjustment and calibration.
