Reverse flow type viscometers are mostly used with dark samples that obscure the timing lines of other tube configurations. Since the sample is timed as it ascends to the timing marks, it is possible to test very dark samples. Approximately 11ml of sample is suctioned into the reservoir bulb with the tube inverted and a stopper is placed in this tube to prevent liquid from flowing. Then the tube is returned to upright position and equilibrated in the bath for 15-20 minutes. After equilibration, the stopper Is removed and sample flows downward into the first bulb, then upward into the two timing bulbs where two timings may be performed on the same sample (requires two stopwatches). The Cannon Fenske Opaque Viscometer is serialized and its certificate contains calibrated Constants for both the lower and upper bulbs. Dual viscosity data may be secured by multiplying the two timings with their respective Constants.

Bath depth required: 10”