1. Washing and drying.
he viscometer must be washed before use. Generally, it is washed repeatedly with a solvent that can dissolve the residue in the viscometer, then washed with alcohol or gasoline, and then washed with fuming sulfuric acid or potassium dichromate lotion. Soak for 2-3 hours, rinse with tap water after the last, rinse with distilled water, put it in the oven, and heat it up to about 150, or put it upside down at natural temperature for a few days, until it evaporates.
2. Filling with oil.
Except for Ubbelohde's direct pouring from the seminal tube, Connect the small glass tube on the seminal tube with a rubber ball (ear-washing ball) or a syringe with a small mouth, hold the viscometer in your left hand and block it with your index finger With a thick tube mouth, turn the viscometer upside down, extend the long glass tube with capillary tube into the sample, pull the syringe, suck the sample to the second circle line (make the liquid surface tangent to the circle line), and then stand it up. . After the counterflow is installed, clamp the latex tube with a clamp and put it on the tube for sucking the sample.
3. Constant temperature and vertical adjustment.
Put the viscometer with the sample on the thermostat shelf (on the clip), adjust the capillary left, right, front and back vertically, keep it at the measuring temperature for 10 minutes, start the measurement, and make a note *The outflow time between the second lap is generally performed three times (remove abnormal numbers) and take the average.
About the Ubbelohde viscometerWhen the fluid is subjected to external forces, there is a tangential internal friction between the flowing liquid layers. If the liquid is to pass through the tube, a portion of the work must be consumed to overcome the resistance of the flow. At low flow rates, the liquid in the tube advances in a straight line parallel to the tube wall. The liquid closest to the tube wall is virtually stationary,