3.5.4　Experiment procedures

(1)Perform the experimental set-up according to Figure 3.5.1.Connect the falling ball viscometer to the pump connection unit of the thermostat with rubber tubing.Fill the bath of the circulating thermostat with distilled or demineralised water to avoid furring.

(2)Set up the target temperature value of the ZKY-PID temperature controller.

(3)Use the micrometer caliper to measure the diameter of the steel ball for eight times to get an accurate value.Measure the inner diameter of the glass cylinder by the vernier caliper.(https://www.daowen.com)

(4)Determine the falling velocity of the ball in liquid.It is necessary to wait for at least 10 mins after the temperature reaches its set value.Place the sphere near the top of the fluid reservoir.Try to get the sphere as close as possible to the air-fluid interface.Release the sphere and begin timing.Record the time of the ball falling a certain distance in the tube.Repeat this experiment for at least 3 times.

(5)Change the heating temperature,and repeat step(4).Attention:lots of spheres are available to measure the viscosity.