1、UDC 532.13.08 : 620.1.05 DEUTSCHE NORM December 1988 Viscometry the Ubbelohde microviscometer Determination of kinematic viscosity using DIN 51 562 Part 2 Viskosimetrie; Messung der kinematischen Viskositt mit dem Ubbelohde-Viskosimeter; Mikro-Ubbelohde-Viskosimeter In keeping with current practice
2、in standards published by the International Organization for Standardization (/SO), a comma has been used throughout as the decimal marker. 1 Scope The method specified in this standard serves to measure the viscosity of small samples under conditions similar to those described in DIN 51 562 Part 1.
3、 The Ubbelohde microviscom- eter specified here permits short flow times to be measured, and small Hagenbach corrections to be used (cf. Explanatory notes). 2 Measurement range The Ubbelohde viscometer is designed for a kinematic vis- cosity range of 0,35 to about 800 mm2/s, at flow times over 100 s
4、 for manual measurement and, generally, over 30 s for automatic measurement; subject to calibration (cf. clause 6), the viscometer may be used for flow times down to 23 to 25 s (depending on the stability of the suspended level). The vis- cometer may generally be employed for fluid temperatures from
5、 +10 to +lOOC. It should be noted that the temperature may range from -40 to +15OoC, but that, in this case, the pre- cision given in clause 8 is not attainable. 3 Sampling and sample size Sampling shall be carried out in accordance with the specifi- cations or standards applicable to the test liqui
6、d, about 2 ml of which will be sufficient for a single charge. 4 Test apparatus See DIN 51 562 Part 1. 4.1 Ubbelohde suspended-level microviscometer Since asingle capillary only permits a small viscosity range to be covered, a number of capillaries of the same length but of different diameters shoul
7、d be used (cf. table 1). The viscometer shall be so designed that the viscometer con- stant, K, does not differ by more than 20% from the guide value given in table 1.Theconstant shall be durable applied on the viscometer by the manufacturer, by etching. 4.2 Automatic flow time measuring device Visc
8、ometers fitted with an automatic flow time meter are pro- vided with signalling devices (e. g. light barriers) instead of fill- ing marks (MI and M2). These divices are to be set for two horizontal measuring planes, the spacing and location of which shall permit the mean driving head and flow volume
9、 specified in subclause 4.1 (below illustration) to be maintai- ned. (cf. figure 1) 12 2 The principal parameters of the viscometer shall be the fol- lowing. a) Length of capillary (7): (130t5)mm. b) Mean driving head, h: (158t5)mm. c) Flow volume, V (8): (0,7510,075) ml. d) Internal diameter of Fig
10、urel. Ubbelohde microviscometer (see DIN 51 562 Part1 for designation of viscometer components) If the signalling devices are not firmly attached to the viscom- eter, their location shall be verifiable, taking the position of the filling marks (or their position on calibration) as the basis. The lim
11、it of error of the automatic flow measuring device shall not exceed 0.01 s. The time base of the device shall be con- stant to within and be equal to the nominal flow time. The signalling devices shall not cause any change in the tem- perature or chemical composition of the test liquid likely to aff
12、ect the test result. level bulb (5): approximately 10 mm Continued on pages 2 and 3 DIN 51 562 Part 2 Engl. Price group 5 Beuth Verlag GmbH, Berlin, has lhe exclusive right of sale for German Standards (DIN-Normen). 02.91 Sales No 0105 Page 2 DIN 51 562 Part 2 Table 1. Dimensions and viscometer cons
13、tants of Ubbelohde microviscorneter Flow vol- Ume, in mi Size num- ber Viscom- eter Kinematic con- viscosity stant, range, u, K, in in m2/s mm2/s2 Internai diam- eter of cap- illary, in mm 1) E/K ratio 2), in s3 41 5 70 - - - 5 Procedure See DIN 51 562 Part 1. Although the Ubbelohde microviscorneter
14、 is not provided with an upper reservoir, the distance travelled by the test liquid before the start of flow time measurement will not affect the measurement result provided the liquid has been sucked or forced up to a level about 20mm above filling mark Mi. When making measurements below the dew po
15、int of ambient air, care shall be taken to prevent condensation in the vis- cometer (cf. DIN 51 550). After measurements made above lOC., the viscometershall be checked for any change in the viscometer constant. 6 Hagenbach correction Where the flow time, f, measured by microviscometers No. M I and
16、M IC is less than 70 s and 40 s respectively, the Hagen- bach correction, At, shall be calculated from equation (1): (1) (Cf. table 1 for E/K values.) Figure 2 provides a graphical representation of the Hagenbach correction so calculated. At shall be subtracted from the measured flow time. The visco
17、sity ranges of Ubbelohde microviscometers No. M I and M IC can be extended to cover flow times shorter than 30s if the individual values for the Hagenbach correction are not determined by calculation from equation (1) but by testing each viscometer in accordance with the method specified in DIN 51 5
18、62 Part 3 using low-viscosity reference liquids. If the viscometer is used for a series of measurements involving flow times of different duration, the individually determined E At=- K . t2 3 t- Figure 2. Graphical representation of the Hagenbach correction Hagenbach correction shall be used instead
19、 of that establi- shed by means of equation (1) as soon as the flow time drops below 70 s or 40 s respectively for capillaries No. M i and M IC respectively. 7 Expression of results The kinematic viscosity shall be expressed in mm2/s, rounded to four places, with a reference to this standard and an
20、indica- tion of the test temperature. 8 Precision If a Hagenbach correction need not be made, the precision to be expected will be in compliance with that specified in DIN 51 562 Part 1. For flow times between 40 and 70s for microviscometer No. M I and flow times between 30 and 40s for microviscomet
21、er No. M IC, the repeatability limit is0,5%and the reproducibility limit, 1 Oh. The precision of measurements made with microviscometers No. M I and M IC can be increased by using individuallydeter- mined Hagenbach corrections (cf. clause 6), which gives a repeatability limit of 0,5% and a reproduci
22、bility limit of 0,7 %. DIN 51 562 Part 2 Page 3 Standards referred to DIN 51 550 DIN 51 562 Part 1 DIN 51 562 Part 3 Determination of viscosity; general principles Determination of kinematic viscosity using the standard design Ubbelohde viscometer Determination of kinematic viscosity using the Ubbel
23、ohde viscometer; relative increment at short flow times Other relevant standards DIN DIN 1342 Part 2 Viscosity of Newtonian liquids DIN 53012 1319 Part 3 Basic concepts in metrology; terminology relating to the uncertainty of measurement and the assessment of measuring instruments Capillary viscomet
24、ry of Newtonian liquids, sources of error and corrections Explanatory notes This standard has been prepared by Technical Committee 831 Viskosimetrie of the NormenausschuB Materialprfung (Materials Testing Standards Committee). DIN 51 562 Part 1 specifies minimum flow times of 200 s. However, if the
25、Hagenbach correction at 200s is not negligibly small, the minimum flow time increases, which is not desirable in the case of particular tests, such as the determination of molar mass from the change in relativeviscosity (cf. DIN 1342 Part 2). Therefore, in most cases, testing as specified in DIN 51
26、562 Part 1 is dispensed with and measurements are made at shorter flow times with Hagenbach corrections exceeding 2%. Since automatic determination of viscosity is acquiring increased significance in achieving a low uncertainty of measurement for short flow times, this is dealt with more in detail h
27、ere (cf. subclause 4.2) than in the corresponding subclause of DIN 51 562 Part 1. As shown in table 1, the capillary diameter of microviscometer No. M I is smaller than of viscometer No. Oc described in DIN 51 562 Part 1. To avoid interferences, special attention shall thus be paid to any form of contamination. International Patent Classification G O1 N 11/00
