What is the function of falling sphere viscometer?
Overview. A falling-sphere viscometer is a device used to measure the viscosity of a fluid by measuring the time required for a spherical ball to fall a certain distance under gravity through a tube filled with the fluid whose viscosity is to be determined.
What are the shortcomings of the falling ball viscometer?
The main disadvantage of capillary viscosimetry is the increase in uncertainty at each stage of the procedure [1]. This comparative method known as “step up” is based on the water’s viscosity which itself is a value measured and subjected to uncertainties [2] but also disputed by a part of the scientific community.
Which spindle is used to measure viscosity?
Each has a recommended sample volume to use for the viscosity test. Cone spindle is by far the one that requires the least amount of material, typically <2 mL.
Which are the parts in the rotational viscometer?
The rotational viscometer consists of two basic parts separated by the fluid being tested. The two parts may be: concentric cylinders (cup and bob), parallel plates, a low angle cone and plate, or a spindle inside of a cylinder. Common spindle shapes, disk, T-bar, cylinder, and vane, are shown below.
What is falling sphere method?
A sphere of known density and diameter is dropped into a large reservoir of the unknown fluid. In this experiment, the speed at which a sphere falls through a viscous fluid is measured by recording the sphere position as a function of time.
What forces act on the ball while falling in a viscous stationary medium?
There are three forces acting on an object falling through a viscous fluid: its weight w, the viscous drag FV, and the buoyant force FB.
Is falling ball viscometer accurate?
Falling Ball Viscometer uses the simple — but precise — Höppler principle to measure the viscosity of Newtonian liquids by measuring the time required for a ball to fall under gravity through a sample-filled tube.
How do I choose a spindle for my viscometer?
When the viscosity of a fluid is not known. Generally, if the reading is above 100% at the lowest speed, the next smallest spindle should be used. If the reading is below 10% at the highest speed, the next largest spindle should be used.
How does Au tube viscometer work?
U-tube viscometers In one arm of the U is a vertical section of precise narrow bore (the capillary). In use, liquid is drawn into the upper bulb by suction, then allowed to flow down through the capillary into the lower bulb. Two marks (one above and one below the upper bulb) indicate a known volume.
What is vibrational viscometer?
Vibrating viscometers are rugged industrial systems used to measure viscosity in the process condition. The active part of the sensor is a vibrating rod. The vibration amplitude varies according to the viscosity of the fluid in which the rod is immersed.
How does Redwood viscometer work?
The redwood viscometer consist of vertical cylindrical oil cup with an orifice in the centre of its base . A hook pointing upward serve as a guide mark for filling the oil . The cylindrical cup is surrounded by the water bath . The water bath maintain the temperature of the oil to be tested at constant temperature .