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
10. Procedure
10.1 Select either Mode A or B operation. (Refer to Table 1 for applicable Mode for a specific fuel.)
NOTE 5 - Only JP 4 requires Mode B operation.
10.1.1 Depress either pushbutton A or B for Mode A or B operation, respectively. Sequential illumination of the pushbuttons will cease and the depressed pushbutton will stay lit. The correct syringe drive speed is set automatically.
10.2 Remove a plunger from a new 50-mL syringe and wipe the tip using a clean, lintless wipe to remove any sheen caused by excess lubricant. Insert a plug into the exit hole of the syringe barrel, add 50 ± 1 mL of fuel, and place the syringe barrel on the emulsifier mount, turning to lock in place. Ensure that the syringe barrel is properly aligned concentrically with the mixer shaft and is not touching the propeller.
10.3 Initiate the CLEAN cycle by depressing the START pushbutton as designated by the annunciator light. (Warning - Do not operate the mixer without having a syringe with fuel in place. The mixer bearings depend on the fuel for lubrication.)
10.4 At the end of the first clean cycle, when the mixer motor stops, press the RESET push-button, remove the syringe barrel from the emulsifier, discard the fuel, and drain the syringe thoroughly. Add 50 ± 1 mL of fresh fuel into the syringe and place (see Note 4) the syringe barrel on the emulsifier mount (turn to lock in place). Visually inspect that the syringe barrel is properly aligned concentrically with the mixer shaft and is not touching the propeller. Select Test Mode A by pressing A push-button.
10.5 Initiate the second CLEAN cycle by pressing the START push-button, as designated by the annunciator light.
10.6 Add about 15 to 20 mL of the fuel to be tested into a new vial. Wipe the outside of the vial with a clean, lintless wiper and insert the vial into the turbidimeter well aligning the black mark on the vial with the line on the front panel.
10.7 At the end of the clean cycle, when the mixer motor stops, remove the syringe barrel from the emulsifier, discard the fuel, and drain the syringe thoroughly. Add 50 ± 1 mL of fresh fuel sample into the syringe.
10.7.1 Handle the syringe in such a manner as to minimize warming of the fuel sample by body heat.
10.8 Using a fresh plastic tip on the hand pipet, add 50 µL of distilled water to the fuel sample as follows: Holding the pipet in hand, give a slight twist to the plastic tip to ensure a tight seal, push in the plunger, immerse the tip just below the water surface, release the plunger, and withdraw from the water slowly to avoid water drops adhering to the outside of the tip. Immerse the tip of the pipet just below the fuel surface in the center of the syringe (Fig. 4) to ensure the water drops break away cleanly and fall to the bottom, push and hold-in the plunger, withdraw the pipet, and release the plunger.
10.9 Place the syringe barrel on the emulsifier mount, turning to lock in place.
10.9.1 Assure that the syringe barrel is properly aligned concentrically with the mixer shaft. Proper alignment can be verified by grasping the syringe barrel and moving the same until the propeller on the end of the mixer shaft is free and not touching. Misalignment may cause plastic shavings to form and collect on the coalescer filter material resulting in erroneous test results. This applies to all instruments manufactured and those which have not been serviced by EMCEE Electronics, Inc. since July of 1988. Since that date, with ASTM approval, all new instruments and those returned for service have had a standoff installed on the mixer shaft to prevent the syringe barrel from coming into contact with the mixer blades.
10.10 With the syringe in place, depress the START pushbutton (Fig. 5) to initiate the automatic portion of the applicable test mode program listed in Table 6. If for any reason it is desired to interrupt the sequence and start over, the RESET pushbutton will cancel the test in progress and reset the program to the beginning of the CLEAN segment of the test cycle.
10.11 The automatic program starts with a read meter indication (four short tones) followed by a 10-s full-scale adjustment period. During this period, the ARROWED pushbuttons will illuminate and can be depressed to adjust the meter to read 100 (Fig. 6). If the adjustment cannot be completed at this time, final adjustment can be accomplished during the second meter adjust period occurring later in the test sequence.
10.12 After the full-scale adjustment period the mixer motor activates and the emulsion process is initiated.
NOTE 6 - A few drops of fuel may seep from the hole in the emulsifier head during the high-speed mixing operation. This should not affect the test results.
10.13 When the mixer stops (after emulsification), remove the syringe barrel from the emulsifier and partially insert the plunger to seal the open end of the syringe (Fig. 8). Invert the syringe (exit hole up), remove the plug, and exhaust the entrapped air in the syringe barrel without significant fuel loss by carefully inserting plunger to the 50 mL mark. (Use a clean wipe over the exit hole to capture the small amounts of fuel which may be extruded as foam (Fig. 9). Affix a new Alumicel coalescer to the end of the syringe barrel.
10.13.1 Place the entire syringe assembly into the syringe drive mechanism (Fig. 7). To minimize the effect of plunger resistance (drag) in the syringe barrel, align the syringe assembly vertically in the syringe drive mechanism with the end of the syringe plunger parallel with pushbar of the syringe drive mechanism. Position a waste container beneath the Alumicel coalescer to collect the unwanted portion of the processed fuel sample during the coalescing period.
10.13.2 Electrically bond Alumicel coalescers to the Micro-Separometer to prevent buildup of an electrostatic charge that could result in ignition of flammable test fluids. Each Mark V instrument is furnished with a ground lead that has an alligator clip on one end and a banana plug on the other. Fasten the alligator clip to the Alumicel coalescer and insert the plug in the chassis ground jack (Fig. 7). Other suitable grounding methods may be used for previous models.
10.14 Four short tones will indicate the second meter adjust period. If required, the operator should adjust the meter reading to 100. The syringe drive mechanism will start down at the end of the meter adjust period forcing the water/fuel emulsion through the Alumicel coalescer (Fig. 7). During this operation remove the vial from the turbidimeter well and discard the fuel.
10.15 Collect the last 15 mL of fuel sample being processed from the Alumicel coalescer (Fig. 8) when the collect sample annunciator lamp (marked C/S) illuminates and a pulsed tone of short duration sounds. To lessen the amount of air introduced into the fuel during this operation, position the vial at a slight angle and allow the fuel to flow down the inner surface. Remove the vial just prior to when the last amount of sample is expelled from the Alumicel coalescer.
10.16 Wipe the outside of the vial with a clean, lintless wiper to remove any fingerprints and fuel. Place the sample vial into the turbidimeter well aligning the marks on the vial and on the control panel in front of the well. At the end of the settling time (1 min), a steady (4-s duration) tone will alert the operator that the meter is about to activate.
10.17 At the end of the tone, the METER will automatically activate for approximately 10 s.
10.17.1 MSEP ratings are read at the midpoint of the 10-s meter read cycle indicated by a short 1-s tone.
NOTE 7 - Numerical values obtained outside the measurement range from 50 to 100 are undefined and invalid (see 5.2).
