The principle of operation of the analyzer is determined by GOST 23453-90 “Method for determining the amount of SA in milk using a viscometer”, according to which the given volumetric quantities of milk and an aqueous solution of the Mastoprim preparation are mixed and then the conditional viscosity of the mixed samples is determined, according to the times of leakage of their identical parts by volume through the capillary. The analyzer measures the outflow times of samples of equal weight (calibration weight) using a strain-electric weighing device (TVU). The calibration weight is equal to the weight of distilled water flowing through the capillary in 8.3 s from a 15 cm3 sample.
During the flow of samples, continuous information from the output of the TVU is processed in order to identify deviations from the uniform laminar flow of liquid through the capillary. This eliminates gross errors, and reduces the contribution of random errors when foreign particles enter the capillary channel, or formations from the interaction of the drug with biologically active milk.
The general view of the analyzer is shown in Fig. 1 and it consists of two main parts: the measuring unit (1) and the mixing unit (2). The electronic part of the device and TVU are located inside the horizontally located measuring unit, and the display indicator (4) and controls (5) are located on the housing (3) covering them. The mixing unit is made in the form of a rack (6), in the upper part of which a stepper motor (7) with grippers for the measuring vessel flask (8) is fixed. A capillary assembly (9) is installed in the cylindrical branch pipe of the flask with a seal and the ability to move along the axis of the branch pipe. In the measurement mode, the measuring vessel is installed vertically and the liquid is drained through the capillary into the bath (10) installed on the working table of the TVU (11).
The new device also has other improvements that increase the reliability of its operation and ergonomic qualities :
- The geared DC motor has been replaced by a stepper motor, eliminating the complicated and unreliable valve mechanism.
- Instead of a mixing block, a flask was developed – a “non-spill”, on which a capillary unit is installed (see Fig.). The flask is installed (or removed) in elastic grips with a simple movement.
- When calibrating measurements on water, it is not necessary to tint it with ink.
- The user receives laboratory scales that can be used in the preparation of Mastoprim solution and other purposes.
- The weight and power consumption of the new device have been reduced by almost 2 times with improved design.
|Metrological and technical characteristics||Values|
|Range of determination of SC concentrations, thousand in 1 cm3||90…1500|
|Conditional viscosity determination range (outflow time), s||12…58|
|Limits of permissible absolute error of the calibration weight:
during initial verification, g
during periodic verification, g
(13.3 ± 0.2)
(13.3 ± 0.3)
|Limit of permissible relative error of the measurement result on the GSO REV-20 from the calculated values according to the verification procedure:
during primary verification, %
during periodic verification, %
|TVU measurement range, g||0…50|
|Limit of permissible reduced error of measurement results of TVU, %||± 0.1|
|Measuring vessel capillary channel diameter, mm||1.5+0.01|
|Range of permissible deviations of the temperature of the measuring vessel and the investigated liquids, °C
in calibration tests
in working measurements
|Average time of one measurement, minutes||4|
|Weight, kg, no more||3|
|Overall dimensions, mm||282x166x240|
|Supply voltage, V||220±10%|
|Power frequency, Hz||50±1|
|Power consumption, VA, no more||20|
|Mean time between failures, hour, not less||2000|