Question

 Questions :-
1.     Describe the process for cleaning the redwood viscometer .
2.     Explain the importance of water bath in redwood viscometer .
3.     Which precaution will be taken while performing the practical.
4.     Explain the way to place the receiving flask .
5.     Name the types of viscometer .
6.     How to mount thermometer in the oil cup.
7.     At what type oil should be heated .
8.     Give the limitations of Able’s closed cup.
9.     Explain the significance of fire & Flash point.
10. Define –Viscosity . Viscosity index , flash & Fire point , oiliness , Volatility ,
11. Define lubricant , Lubrications
12. Types of lubricants .
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Answer 1

Answer:

1.

(1) Clean the cylindrical oil cup and ensure the orifice tube is free from dirt .

(2) Close the orifice with ball valve.

(3) Place the 50 ml flask below the opening of the Orifice .

(4) Fill the oil in the cylindrical oil cup upto the mark in the cup .

(5) Fill the water in the water bath.

(6) Insert the thermometers in their respective places to measure the oil and water bath

temperatures.

(7) Heat the by heating the water bath, Stirred the water bath and maintain the uniform

temperature .

(8) At particular temperature lift the bal valve and collect the oil in the 50 ml flask and

note the time taken in seconds for the collecting 50 ml of oil . A stop watch is used

measure the time taken . This time is called Redwood seconds .

(9) Increase the temperature and repeat the procedure ‘8’ and note down the Redwood

seconds for different temperatures .

2.

The redwood viscometer consist of vertical cylindrical oil cup with an orifice in the

centre of its base . The orifice can be closed by a ball . 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 . The oil is heated

by heating the water bath by means of an immersed electric heater in the water bath , The

provision is made for stirring the water , to maintain the uniform temperature in the water

bath and to place the thermometer ti record the temperature of oil and water bath . The

cylinder is 47.625mm in diameter and 88.90mm deep . The orifice is 1.70mm in diameter and

12mm in length , This viscometer is used to determine the kinematic viscosity of the oil.

From the kinematic viscosity the dynamic viscosity is determined .

3.

Do not touch or taste any unknown substance.

Use only small quantity of chemical to carry out experiment.

Do not work alone in the laboratory.

Do not throw hot concentrated acids into the sink directly.

Always wear an apron in the laboratory to protect your clothes.

While heating keep the mouth of test tube away from your eyes and face.

The apparatus to be used in an experiment should be arranged neatly before beginning an experiment.

Do not throw broken glass apparatus or used filter paper in the sink. Throw them in a dustbin.

4.

The proper method is to connect the input hose to the condenser at the end furthest from the heated flask and the outflow hose nearest the heated flask. This prevents the hottest vapors from contacting the coldest water and creating a large thermal shock to the glassware

5.

6 different types

Orifice viscometers.

Capillary viscometers.

Falling piston viscometers.

Rotational viscometers.

Falling ball viscometers.

Vibrational viscometers.

8.1. It lacks precision. 2. It gives a higher flash point than a closed cup as it allows free loss of vapours to the atmosphere.

9.

Significance:-

1) The fire point is used to assess the risk of the materials ability to support combustion.

2) These values can also affect how the fluid may be shipped, stored, and discarded.

10.The viscosity of a fluid is a measure of its resistance to deformation at a given rate.

Viscosity index-The viscosity index (VI) is an arbitrary, unit-less measure of a fluid's change in viscosity relative to temperature change. It is mostly used to characterize the viscosity-temperature behavior of lubricating oils.

Flash point: It is the lowest temperature at which vapours of the material will ignite, given an ignition source.

Fire point: The fire point of a fuel is the lowest temperature at which the vapour of that fuel will continue to burn for at least 5 seconds after ignition by an open flame.

The term “oiliness” is defined as that property of lubricants by virtue of which one fluid gives lower coefficients of friction (generally at slow speeds or high loads) than another fluid of the same viscosity.

Volatility is the tendency of a substance to evaporate at normal temperatures.

11.

Lubricants -

A lubricant is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move.

Lubrication- Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces.

12.

There are three different types of lubrication: boundary, mixed and full film.

Hope it is clear