1、 FORD LABORATORY TEST METHOD BJ 127-01 Date Action Revisions 2001 07 25 Revised Editorial no technical change A. Cockman 1990 05 17 Printed copies are uncontrolled Page 1 of 8 Copyright 2001, Ford Global Technologies, Inc. SCANNING BROOKFIELD VISCOMETER TEST FOR LOW TEMPERATURE ENGINE OIL PUMPABILIT
2、Y Application This procedure measures certain low temperature viscometric characteristics of an engine oil which may inhibit flow to the oil pump and, subsequently, to the sites in the engine requiring lubrication. Summary of the Method An engine oil, preheated to a specified temperature, is placed
3、in a special test cell immersed in a temperature programmable liquid bath. Viscometric analysis is performed continuously by a rotor turning within the test cell as the temperature is lowered slowly through the temperature range of interest. The torque required to shear the oil is recorded on a char
4、t recorder to determine the Scanning Brookfield Viscosity. Apparatus Required* Programmable Liquid Bath A Siverso Programmable Liquid Bath, Model 410, or equivalent, capable of controlling the rate of decrease of the bath temperature to 1 C/h (+/- 1 C). (Special bath covers and other accessories nec
5、essary to complete the bath assemblage are noted under this section concerning the test cell). Viscometer A Brookfield Digital Viscometer, 5X LVTD, or equivalent, with analog output. Recorder Two-channel Linear Model 1202, or equivalent. (The analog torque signal from the viscometer is recorded cont
6、inuously on one channel and the bath temperature is monitored on the other (to assure linearity of cool down). The chart speed is selected to correspond to 0.1 C) per division.) Test Cell SavTec SBV-1 (shown in Figure 1) or equivalent consisting of: 1. A glass container (stator), SavTec SBV-S1, for
7、the test oil. 2. A cell cap, SavTec SBV-C1. 3. A rotor, SavTec SBV-R1. 4. A retaining clip (retainer), SavTec SBV-RC1, to hold the rotor in position when not connected to the viscometer. FORD LABORATORY TEST METHOD BJ 127-01 Page 2 of 8 Copyright 2001, Ford Global Technologies, Inc. The test cell is
8、 supported in the liquid bath by a special Bath Cover Kit, SavTec SBV-T1 or equivalent. * Source: Tannas Co. P.O. Box 327 Midland, Michigan 48640 Materials Required* Dry Air Source In humid conditions, a source of dry air blowing gently across the cell cap is necessary to control the accumulation of
9、 frost around the rotor spindle. Coordinate Paper A special coordinate paper was developed from a simplified version of the Walther/ASTM equation: ln (ln (viscosity) = m (ln (absolute temperature) + b in which “m“ and “b“ are the slope and intercept values respectively. This coordinate paper, SavTec
10、 SBV-CP (shown in Figure 2) or equivalent, may be used to plot the viscometric values taken from the chart paper to more clearly identify any non-Newtonian viscometric responses of the engine oil (such as gelation). Reference Oil A Newtonian Reference Oil, SavTec LN-P or equivalent, is used to calib
11、rate the test cell. * Source: Tannas Co. P.O. Box 327 Midland, Michigan 48640 Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and test
12、ed under the same conditions unless otherwise specified. Test Procedure In the subsequent descriptions of the test conditions and throughout the remainder of the description of the test method, all temperature values below 23 +/- 2 C imply a variation within +/- 0.05 C. FORD LABORATORY TEST METHOD B
13、J 127-01 Page 3 of 8 Copyright 2001, Ford Global Technologies, Inc. The engine oil to be tested is heated in a 50 mL glass beaker to a temperature not less than 80 C and not more than 90 C for at least 15 minutes and not more than one hour, following which 15 mL are poured into the test cell. After
14、positioning the rotor in the test cell, the cell is placed in the liquid bath (which has previously been brought to the initial test temperature of 5 C) and the rotor attached to the viscometer drive shaft. When the viscometer is turned on and zeroed on the chart, the relative rotor/stator alignment
15、 is adjusted for concentricity. When this has been accomplished, the cool-down program of 1 C/ hour is initiated. The test is terminated when the viscometer readout registers “EEE“, a signal given at about 43 to 45 Pa.s. The analog signal from the viscometer is adjusted so that the viscosity in Pa.s
16、 can be read from the chart recording. A. Calibration of the Test Cell 1. Fifteen millitres of the Newtonian Reference Oil are poured into the test cell and the cell assembled with rotor, cap and retainer. 2. The liquid bath is programmed as follows: Temperature, Time, degrees C minutes Activity + 5
17、 30 adjust recorder Decreasing temperature - 5 30 adjust recorder portion of program -15 30 adjust recorder -19 30 adjust recorder -15 30 note recorded viscosity Increasing temperature -10 30 note recorded viscosity portion of program - 5 30 note recorded viscosity 0 30 note recorded viscosity + 5 3
18、0 note recorded viscosity 3. Before initiating the program in paragraph 2 of the Test Procedure (immediately above), the Viscometer drive spindle is adjusted to be vertical by means of the “bulls eye“ level attached to the Viscometer head. Following this, the stator is filled with 15 mL of the Refer
19、ence Oil, the test cell immersed in the liquid bath, and the rotor first zeroed on the chart paper and then centered in the Stator by 1) removing the retainer and connecting the rotor to the viscometer head, 2) lowering the rotor into the Reference Oil to the rotor notch, 3) turning the viscometer o
20、n and selecting the maximum speed permitting on-scale torque measurement (usually about 3 to 6 rpm), and 4) laterally moving the rotor (by swiveling the viscometer post) and/or the stator (by moving the bath cover lids supporting the cell). The rotor is considered centered when the lateral adjustmen
21、t of the rotor and/or the stator produce a relatively smooth line on the recorder paper of lowest consistent torque when several revolutions of the rotor have been recorded. FORD LABORATORY TEST METHOD BJ 127-01 Page 4 of 8 Copyright 2001, Ford Global Technologies, Inc. 4. The bath cooling program i
22、s initiated. During the decreasing temperature portion of the temperature control program, when the Reference Oil is at temperature equilibrium as indicated by a relatively constant torque line on the chart, the position of the pen on the chart recorder is adjusted to reflect the viscosity of the Re
23、ference Oil at that temperature as given on the Reference Oil certificate. When the temperature has reached -19 C, the increasing temperature program of paragraph 2 above provides a comparison of recorded viscosity values versus the Reference Oil values as follows: The recorder pen is no longer adju
24、sted to the certified viscosity values but, rather, the values obtained from the chart are compared to the values from the Reference Oil certificate using regression analysis which should yield a correlation coefficient of 0.9999 as evidence of the agreement between the values. If such a correlation
25、 coefficient is not obtained, the test should be repeated once more and, if this level of agreement is not obtained, this should be considered as evidence of, and the need to determine the cause of, some other systematic error or equipment malfunction. An example of such a comparison is shown in Tab
26、le 1. B. Testing 1. The liquid bath is programmed for a constant rate of cool-down at 1 C/hour to be initiated at -5 C. The bath is brought to the initial temperature of 5 C and held at this temperature until the cooling cycle is activated. 2. A 20 to 30 mL sample of the engine oil to be tested is p
27、oured into a 50 mL beaker and heated to between 80 and 90 C for at least 15 minutes and not more than an hour. 3. The calibrated stator is filled with 15 mL of the test oil and the test cell assembled with the rotor, cap and retainer as in Figure 1. 4. The test cell is placed in the bath within 10 m
28、inutes of removing the test oil from the heat source and the rotor connected to the drive shaft of the viscometer head. The rotor is adjusted to align the notch on the rotor shaft with the test oil level. 5. The recorder is turned on but the pen and paper drives are not yet engaged. Rather, the char
29、t pen and the viscometer analog output signal are zeroed using the requisite controls on each device. 6. The rotor is centered in the stator as already described in paragraph 3 of the Calibration Procedure. 7. The viscometer speed is set at 0.3 rpm on the viscometer head, the chart paper drive and t
30、he pen drive started, and the bath cooling program initiated. FORD LABORATORY TEST METHOD BJ 127-01 Page 5 of 8 Copyright 2001, Ford Global Technologies, Inc. 8. The cooling program is allowed to run until the viscometer readout is “EEE“ indicating an over-range condition. At this point the test is
31、terminated. Plotting the viscosity/temperature data from the chart recording onto the logarithmic coordinate paper described in the Apparatus Section gives further information on the test oils viscometric properties. C. Analysis of Test Results While there are a number of ways of applying the data,
32、one use of the test results is by determining the temperature at which the Scanning Brookfield Viscosity reaches a certain maximum viscosity. For example, if the critical viscosity is considered to be 40 Pa.s, then a system of evaluation might be: Maximum Viscosity Maximum SAE Grade Permitted, Pa.s
33、Temperature 0w 40 - 35 C 5w 40 - 30 C 10w 40 - 25 C 15w 40 - 20 C 20w 40 - 15 C Precision The repeatability of the Scanning Brookfield Viscosity is dependent upon the viscometric characteristics of the oil; an oil which increased viscosity very rapidly with decreasing temperature would show lower re
34、peatability than one whose viscosity increased less precipitously. An alternative means of evaluating the repeatability of the method with any oil is to use the temperature at which the oil reaches a given viscosity. Applying this approach, the repeatability of the Scanning Brookfield Viscosity test
35、 method is indicated as +/- 1 C at a confidence level of 95 %. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD BJ 127-01 Page 6 o
36、f 8 Copyright 2001, Ford Global Technologies, Inc. TABLE 1 Example of Test Cell Calibration Temp., C Certificate Determined Viscosity Pa.s Activity + 5 1.27 - Set viscosity - 5 4.39 - Reset viscosity - 10 8.99 - Reset viscosity - 15 19.87 - Reset viscosity - 19 39.90 39.5 Comparison - 15 19.87 19.8
37、Comparison - 10 8.99 9.3 Comparison - 5 4.39 4.7 Comparison 0 2.29 2.7 Comparison + 5 1.27 - Not determined Correlation Coefficient: 0.999993 Slope: 1.022 Intercept: -.449 Pa.s FORD LABORATORY TEST METHOD BJ 127-01 Page 7 of 8 Copyright 2001, Ford Global Technologies, Inc. SCANNING BROOKFIELD VISCOMETER TEST FOR LOW TEMPERATURE ENGINE OIL PUMPABILITY Figure 1 FORD LABORATORY TEST METHOD BJ 127-01 Page 8 of 8 Copyright 2001, Ford Global Technologies, Inc. SCANNING BROOKFIELD VISCOMETER TEST FOR LOW TEMPERATURE ENGINE OIL PUMPABILITY
