ASTM D3948 Determining Water Separation Characteristics of Aviation Turbine Fuels
ASTM D3948 Standard Test Method for Determining Water Separation Characteristics of Aviation Turbine Fuels by Portable Separometer
6. Apparatus
6.1 A Micro-Separometer is used to perform the test. The unit is completely portable and self-contained, capable of operating on an internal rechargeable battery pack or being connected to an a-c power source using power cords which are available for various voltages. Connection to an a-c power source will provide power to the unit and effect battery recharge. The accessories as well as the expendable materials for six tests can be packed in the cover of the lockable case.
6.2 The Micro-Separometer Mark V Deluxe and associated control panel is shown in Fig. 1. The emulsifier is on the right side of the raised panel and the syringe drive mechanism is on the left side. The control panel containing the operating controls is mounted on the fixed panel in the left side of the case. Table 2 lists the manual and audio operating characteristics of the instrument.
6.2.1 All of the controls are located in a pushbutton array on the control panel. The pushbuttons illuminate when depressed thus indicating operational status. A circuit breaker located on the control panel provides protection for the a-c power circuit.
6.2.2 By depressing the ON pushbutton, the electronic circuits are energized. The ON pushbutton pulses on and off when the instrument is being operated by an a-c source and constantly remains on when the battery (d-c) pack is used. The lettered pushbuttons will sequentially illuminate on and off indicating READY operational status.
NOTE 1 - Of the lettered (A-G) pushbuttons, only the A and B push-buttons are applicable to this test method.
6.2.3 The RESET pushbutton can be depressed at any time to cancel the test in progress and restore the program to the initial start mode. The lettered pushbuttons commence to sequentially illuminate, thus indicating a READY operational status enabling test mode selection.
6.2.4 Selection of test Mode A or test Mode B programs is accomplished by depressing either the A or B lettered push-button. The depressed pushbutton illuminates and the sequential illumination of the other lettered pushbuttons ceases. The START pushbutton also illuminates.
6.2.5 The START pushbutton, when depressed initially, initiates the CLEAN cycle causing the syringe drive mechanism to travel to the UP position and the emulsifier motor to operate for the cleaning operation.
6.2.6 The START pushbutton, when depressed after the CLEAN cycle initiates the automatic program sequence causing the read indicator and the two ARROWED pushbuttons to illuminate, indicating that a full-scale adjustment period is in effect. A numerical value also appears on the meter.
6.2.7 The turbidimeter is located under the main control panel and consists of a well in which the sample vial is placed, a light source, and a photocell.
6.2.8 By depressing the appropriate ARROWED pushbutton, the displayed value on the meter can be increased or decreased, as required, to attain the 100 reference level for the vial of fuel sample in the turbidimeter.
6.3 Accessory equipment and expendable materials needed to perform the test are shown in Fig. 2 and consist of the following:
6.3.1 Syringe Plug, (A) - A plastic plug used to stopper the syringe during the CLEAN and EMULSION cycles.
6.3.2 Syringe, (Barrel (B) and Plunger (C)) - A disposable plastic syringe.
6.3.2.1 Use of syringes other than those demonstrated to be free of surfactant contamination in a precision program such as described in Section 12 will render test results invalid.
6.3.3 Vials, (D), 25-mm outside diameter vial premarked for proper alignment in the turbidimeter well.
6.3.4 Alumicel, Coalescer, (E) labeled for use with jet fuel, an expendable, precalibrated aluminum coalescer cell with a tapered end to fit the syringe.
6.3.5 Pipet, (G) with Plastic Tip (F) - An automatic hand pipet with a disposable plastic tip. A pipet is supplied with each Micro-Separometer.
6.3.6 Wire Aid, (H) - A piece of wire with a loop on one end, used during test to release the air trapped in the barrel of the syringe when the plunger is being inserted. A wire aid is supplied with each Micro-Separometer.
6.3.7 Water Container - A clean container for distilled water (not shown or supplied).
6.3.8 Beaker, Catch Pan, or Plastic Container - Supplied with each Micro-Separometer may be used to receive the waste fuel during the coalescence period of the test (not shown).
6.4 A new syringe, pipet tip, test sample vials, syringe plug and Alumicel coalescer are used in each test. These expendable materials are available in a kit containing supplies for six tests. This kit termed Micro-Separometer Six Pack isdesigned to fit inside the top lid of the Micro-Separometer (Fig. 3).
7. Reagents
7.1 Aerosol OT, solid (100 % dry) bis-2-ethylhexyl sodium sulfosuccinate.
7.2 Toluene, ACS reagent grade. (Warning - Flammable. Vapor harmful.).
7.3 Dispersing Agent - Toluene solution (Warning - Flammable. Vapor harmful.) containing 1 mg of Aerosol OT per millilitre of toluene.
7.4 Reference Fluid Base - A surfactant-free clean hydrocarbon material which is used to verify proper operation and is prepared in the manner described in Appendix X1. (Warning - Flammable. Vapor harmful.)
7.5 Reference Fluids - (Warning - Flammable. Vapor harmful.) (for checking the operational performance of the Micro-Separometer instrumentation) consist of increasing concentrations (0 to 1.2 mL/L) of dispersing agent added to the reference fluid base. The MSEP-A ratings for this range of concentration appear in Table 3 for Jet A, Jet A-1, MIL JP 5, MIL JP 7, and MIL JP 8 fuels and Table 4 for Jet B fuels using Mode A. The MSEP-B ratings for MIL JP 4 fuels using Mode B are shown in Table 5. The reference fluids are tested as described in Section 10 using the applicable Mode of operation. If the results do not fall within the range of limits shown in Table 3, Table 4, or Table 5, the reference fluid shall be discarded and 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.
NOTE 2 - The reference fluid base should have standard MSEP rating of 99+ without any dispersing agent; otherwise, the results may not be indicative of the accuracy of the instrument. Values obtained outside the measurement range from 50 to 100 are undefined and invalid.
7.5.1 Reference fluid shall be prepared by adding dispersing agent as described in 7.3 to a suitable quantity of reference fuel base contained in a properly equilibrated container or graduate.
7.5.1.1 If a new or nonequilibrated container is used, the additive may adsorb on the walls and the MSEP ratings may improve significantly. To equilibrate the container surface, an additive blend should be held for a minimum of 24 h, discarded, and replaced with a fresh blend.
7.5.1.2 For field use, instrument calibration can be verified by performing MSEP tests using a dilution of the dispersing agent (as prepared in 7.3), a reference fluid base (as prepared in Appendix X1), and distilled water. A 10:1 dilution is prepared by diluting 10 mL of dispersing agent with 90 mL of toluene (7.2). Since 1 mL of dilution is equal to 0.1 mL of dispersing agent, 50 µL 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 3, Table 4, and Table 5. This facilitates using the 50 µL pipet (6.5.5 ) to add increments of 0.1 mL/L of dispersing agent, as well as the 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.
7.6 Water, clean, distilled, and surfactant free.
7.6.1 Use of water other than distilled water (such as tap water) will render test results invalid.
