DETERMINATION OF VISCOSITY OF A LIQUID SAMPLE USING THE U-TUBE VISCOMETER

DETERMINATION OF VISCOSITY OF A LIQUID SAMPLE USING THE U-TUBE VISCOMETER

Aim:to determine the viscosity of a liquid sample using u-tube viscometer

Apparatus: electrical water bath, u-tube viscometer mercury led thermometer, stop watch.

Sample: any liquid

Theory/definition

Viscosity is the resistance to flow in a liquid i.e. the thickness of a liquid. Viscosity of a liquid determine the usefulness of the liquid, e.g.the oil use for a generator is differ from the oil use in an heavy truck in terms of thickness. viscosity can be determine using kinematic and dynamitic method.

Relationship between the kinematic and dynamic viscosity

Kinematic= dynamitic/density

Procedures 

•         Power on the water bath and set it to desire the temperature

•         Insert a rectangular mental block in the water bath to hold the viscometer.

•         Pour the sample into the viscometer and place it in the water bath.
•         Use the thermometer to test the temperature, when it get to the desire temperature leave it for another 15 minutes to be condition with the temperature of the water bath.

•         Bring out the viscometer from the water bath and use a pipette filler to suck the liquid above the upper mark point,allow the liquid to flow down, immediately it gets to the upper mark point start the stop watch and when it gets to the bottom mark point, stop the stop watch.
•         Then convert the time to seconds and multiply it with the u-tube viscometer standard value.(every viscometer tube has it own standard value)

Note: The above procedure is known as kinematic method.

relationship between the kinaematic and dynamatic viscosity
kinematic viscosity= dynamatic viscosity/density