 Professor Dr. Prakash Sawanke from Walshchan Institute of Technology, today we are going to discuss the topic study of comparators, that is from the meteorology subject. At the end of this session, students will describe the meaning, role, and classification of comparators. They will be able to explain principle of working of comparators, introduction to comparators. First, what do you understand by the word comparator, what the word comparator signifies, yes, yes. Comparator means, it is an instrument which is used to compare the dimension of component with a working standard. So it basically compares with the standards and measures the deviation. So it indicates a deviation from the expected or basic dimension. Now this expected or basic dimension is set in the form of some standard. So comparator will not give the direct value of the say dimension but it will measure the deviation from it. Basically the deviation is small and hence it needs a magnification. So it is magnified in comparator. Widely, it is widely used in mass production because of its merits and overmeasuring instruments as well as limit gauges. So let us see what are the merits of comparators. Measuring instruments, if we consider they need skilled operator to use. So you might have seen Vernier, Gallipur or Micrometer. So they need skilled operator, so who can read, I mean do the adjustment. So it consumes more time for the measurement and because of which they are not suitable in mass production. However, one advantage of measuring instrument is that so they give the values of the, I mean quantity that is measured or the dimension that is being measured so which become useful in data so that is useful and they provide useful data which is needed for statistical process control or statistical quality control. So both. So this is as far as the measuring instruments. If we consider the limit gauges which are used normally in case of mass production they are simple to use and they don't need skilled operators. They are fast and economical and become useful in mass production. However, say they check whether the component lies within the limits, maximum and minimum. So only that is checked. So they will not give any value, any data, any reading so which can be used or which is necessary in case of SBC or SQC so that is not provided. So comparators combine advantages of both. They can work as limit gauges for fast operation in mass production with unskilled operator and whenever needed say the deviation can be measured and data becomes useful say for SBC so that data is provided say with the help of this semi-comparators. So we can find actual dimension also say by adding or subtracting the deviation from the standard value so that is the advantage. So if we consider the applications of comparator basically they can be used as laboratory standards so in tool rooms and the controlled atmosphere so they will be used for I mean calibration of the gauges so they act as a laboratory standards. Secondly they can also be used as working gauges and even they can be used as limit gauges by setting the limits of the for the division maximum and minimum so they can be used as working gauges. Similarly final inspection at the time of assembly or after the assembly for final checking of the products so that can be comparators can be used. Comparators can also be used as receiving inspection gauges for the material of the components which is coming say from outside in the industry say which is bought out components as well as raw materials and say they it can also be used for calibration of new gauges so that are manufactured so in that case that act as a standard for the calibration. Requirements of good comparator so what are the I mean requirements or what are the characteristics that are required for the comparators. Firstly first say it should have a robust design and construction because it is used widely and in case of in case of mass production in industry so because the wide is it news robust design. Secondly linearity of scale so that is always expected of any measuring instrument it is the same. Third important is high magnification basically comparators are measuring the deviation from the standard so which will be having a very small amount if in case of dimension it will be in microns. So it cannot be indicated directly so it needs magnification that is this first operation. Since we have to use it in mass production say when thousands or millions of components are I mean being produced so they must be checked firstly so first operation. One more thing is versatility and flexibility so the same comparator can be used to check variety of dimensions or variety of measurements and variety of components. So there should be scope for adjusting say that particular I mean sensing element and some clamping and all at this arrangement so that variety type of dimensions and variety type of components can be accommodated. Of course for any product durability is one of the common requirements so that is also expected in very good comparator and environmental stability because say there will be going to various I mean variety of environments as the season changes temperature will be changing humidity will be changing so many things thus particles. So environmental stability so that should be there so that is expected then only a comparator will be really useful say for working in the industry. Now classification of comparators, comparators are classified based on the method that is used for magnifying and recording the deviation measured so the majority of the groups in which say competitors are classified are as follows one is mechanical another is optical then third is pneumatical then electrical oblique electronic magnetic then combined such as electromechanical mechano optical etc then multi-check so simultaneously there can be number of dimensions that can be checked so that is also possible so then that kind of comparator is multi-check then automatic gauging so nowadays with automatic I mean with the help of the computers and other I mean microprocessors so automating gauges has become possible so in mechanical comparators mechanical means are used for magnification and recording so that is mechanical in case of optical it is optical principles in case of pneumatical it will be pneumatical principles likewise electrical principles magnetic principle etc according to that say the classification is done normally if we consider the working and use of comparators say normally first selecting the dimensions to be measured and accordingly appropriate standard has to be set second step is determination of tolerance limit so what is the maximum deviation and what is the minimum deviation from this standard so that is expected so that is that has to be determined the next stage is initial setting 0 for standard dimension so what is expected size expected dimensions for that some standard which might be in the power of standard component or it might be sleep gauges so that is set and then sensing element normally it may be some kind of spindle stylus so that is touched to it and say for this initial setting 0 is adjusted then the standard is replaced by the components that are to be measured say one by one then recording the deviation from the standard which could be positive negative or 0 if the component that is measured with having major I mean greater size than the standard then say there will be a positive division if it is having a smaller size there will be negative division if it is exactly equal it will be 0 so then we can calculate the actual dimension if necessary then one more possibility that setting the maximum and minimum limits on the dial and use it as a limit gauge so we can set the maximum and minimum limits and if the component is deviation is lying within the limits we can accept it if it is going outside then reject it so there is no need to even record the deviation when we are using the comparator as a limit gauge so that is working as a limit gauge so if we see general elements of the comparator so there are normally sensing element so it will change the say I mean displacement or deviation then second is transmission the sense deviation may be transmitted then there may be transducer the element may be converted into another variable if needed then there is a magnification or amplification say that is needed and finally display of the deviation so these are the general components of any kind of transducers the reference for this material is taken from the textbook of meteorology by M Mahajan, Dharpatra and company private limited so we end our preliminary discussion on the comparators here thank you