Page Contents
1. Purpose
To ensure that Brookfield Viscometer is working properly.
2. Scope
Brookfield Viscometer is applicable for analytical testing of suspension and liquid raw materials in the quality control department.
3. Responsibility
Quality control manager
Analyst
4. Introduction
Viscosity is a measure of a fluid’s resistance to flow. it is to drive a spindle (which is immersed in the test fluid) through a calibrated spring. The viscous drag of the fluid against the spindle is measured by the spring deflection. Spring deflection is measured with a rotary transducer.
5. Operating instructions Of Brookfield Viscometer
Check the spirit level of the viscometer every time before use. The level is adjusted by using the two leveling screws on the base. Adjust so that the spirit level on top of the instrument is centered within the circle.
5.1 Ensure the calibration status is valid and turn the power switch located on the rear panel to the “ON” position.
5.2 This will result in different screen displays and after a few seconds, the screen displays REMOVE SPINDLE, PRESS ANY KEY.
5.3 After removing the spindle (if attached to it) and pressing any key, the instrument begins its auto-zero. The screen will blink “AUTOZEROING”.
Note: Be sure that the viscometer is leveled before this operation.
5.4 After a few seconds, the blinking spots and the following are displayed REPLACE SPINDLE, PRESS ANY KEY, pressing any key at this point result is in the display of the instrument default screen.
5.5 Connect the selected spindle to the viscometer by screwing them to the lower shaft. The lower shaft should be held in one hand and lifted up and the spindle should be screwed to the left.
5.6 Spindles are identified by the number on the side of the spindle nut.
5.7 The two-digit entry code for the selected spindle should be entered by pressing the SELECT SPINDLE KEY, ON PRESSING it once, the top line of the display will begin to blink.
5.8 Then press the UP or DOWN arrow keys for increasing or decreasing the number which is to the right of the ‘s’ is blinking, until the requirement spindle value is displayed.
5.9 The two-digit entry code for each spindle is given below;
SPINDLE NUMBER 1 (LV1)
TWO-DIGIT CODE 61
SPINDLE NUMBER 2 (LV2)
TWO-DIGIT CODE 62
SPINDLE NUMBER 3 (LV3)
TWO-DIGIT CODE 63
SPINDLE NUMBER 4 (LV4)
TWO-DIGIT CODE 64
5.10 Then press the SELECT SPINDLE key once again after selecting the desired spindle code. This will cause the ‘s’ character to cease blinking and the new spindle code will be displayed and accepted for use.
5.11 Then select the speed for the spindle by first pressing either the UP or DOWN arrow keys, which will cause the area to the right of RPM (on the bottom line) to display the currently selected speed. If the arrow key is pressed just once and then released, the character’s RPM will blink for a few seconds and then will cease blinking, resulting in no change to the speed entry.
5.12 Press the UP or DOWN arrow key until the desired speed is displayed and then released it.
5.13 Then press the AUTO RANGE key, which displays the maximum calculated viscosity (full-scale reading) which can be measured with the current spindle/speed setting.
5.14 If the viscosity of the test fluid is greater than the AUTO RANGE displayed, then “cp EEEE” and ‘%EEEE’ will be displayed when operated with this test fluid.
5.15 Change either the spindle or speed to achieve maximum accuracy with the auto range.
5.16 Pressing and holding the AUTO RANGE key during power on will enable the viscosity display to read cps or m.pas. 1cPs = 1 Milli pascal.
5.17 Insert and center the spindle in the test material until the fluid level is at the immersion groove in the spindle shaft. Press the MOTOR ON/OFF key once to turn the motor ON.
5.18 Allow time for the indicated reading to stabilize. For maximum accuracy, reading below 10% torque must not be taken.
5.19 Press the MOTOR ON/OFF key once again to turn the motor OFF when changing a spindle/speed or changing samples.
5.20 Remove the spindle before cleaning and clean it after use.
6. Calibration procedure of Brookfield Viscometer
6.1 Ensure the instrument is clean and free from dust.
6.2 Check the spirit level of the viscometer every time before use. The level is adjusted by using the three leveling screws on the base. Adjust, so that the spirit level on top of the instrument is centered within the circle.
6.3 Turn the power switch located on the rear panel on the ON position.
6.4 Place the viscosity standard fluid (in a 500ml beaker) into the water bath.
6.5 The viscosity standard fluid, should be immersed in the bath for a minimum of one hour, stirring the fluid periodically, prior to taking measurements.
6.6 After one hour, check the temperature of the viscosity standard fluid with a thermometer. It must be within 25.
6.7 Attach the desired spindle to the viscometer.
6.8 Measure the viscosity and record the reading including % and cps at three different speeds using the same spindle.
Calculate the mean value. The mean viscosity reading should equal the cps value on the viscosity fluid standard to within the combined accuracies of the viscometer and the standard.
6.9 For a 2,500 standard fluid with a viscosity at 12,720cPs at 25oC, the acceptance criteria is between 12,393 and 13,047cps by using spindle 4 at a speed of 30 RPM. Similarly, at 20 RPM it is between 12,393 and 13,147cps and at 12 RPM it is between 12,093 and 13,347cps.
6.10 After checking the viscosity of the standard then transfer the fluid back to the bottle without any contamination.
6.11 Calculation for the acceptance limit of the standard fluid full-scale viscosity range = TK SMC 10000/RPM
Where,
TK is a torque constant,
SMC is a spindle multiplayer constant and
RPM is a rotation per minute.
=20,000 cps
200cps (1% of 20,000) + 127.2cps (1% of 12,750cps) = 327.2cps
Table 1: SMC and TK constants (for different spindles)
SPINDLE LV1
SMC 6.4
TK 0.09373
SPINDLE LV2
SMC 32
TK 0.09373
SPINDLE LV3
SMC 128
TK 0.09373
SPINDLE LV4
SMC 640
TK 0.09373
7. Frequency of calibration
Once a month.
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