METROLOGY MEASURING INSTRUMENTS EBOOK DOWNLOAD!
Measured quantity and the measure having a value very near to it (comparator). Measuring instruments may be used in conjunction with separate material measures (e.g. reproduce the unit (like graduated rules, a precision thread, etc.). Measuring Instruments Gauge Blocks & Accessories by Metrology Direct Measuring Instruments Dial, Bore Gauges & Thickness Gauges by Metrology Direct. A measuring instrument is a device for measuring a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events.
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Combination instruments[ edit ] Multimetercombines the functions of ammeter, voltmeter and ohmmeter as a minimum.
Measuring Instruments (Metrology)
LCR metercombines the functions of ohmmeter, capacitance meter and inductance meter. Also called component bridge due to the bridge circuit method of measurement.
Thermodynamics [ edit metrology measuring instruments Temperature -related considerations dominate thermodynamics.
There are metrology measuring instruments distinct thermal properties: The equipment chosen for a particular measurement must bear some metrology measuring instruments to the desired accuracy in the result, and as a general rule, an instrument which can be read to the next decimal place beyond that required in the measurement should be used, i.
When attempts are made to achieve higher accuracy in the measuring instruments, they become increasingly sensitive.
It may be realized that the degree of sensitivity of an instrument is not necessarily the same all over the range of its readings. Another important consideration for achieving higher accuracy is that the readings obtained for a given quantity should be metrology measuring instruments all the time, i.
It may also be remembered that the range of measurement usually decreases as the magnification increases and the instrument may be more affected by temperature variations and be more dependent upon skill in use. Thus, it is true to say that a highly accurate instrument possesses both greater sensitivity and consistency.
But at the same time an instrument which is sensitive and consistent need not necessarily be accurate because the standard from metrology measuring instruments its scale is calibrated may be wrong. It is, of course, presupposed that there always exists an instrument whose accuracy is greater than the one with which we are concerned.
In such an instrument, the errors will be constant at any given reading and therefore, it would be quite possible to calibrate it.
It is very obvious that higher accuracy can be achieved by incorporating the magnifying devices in the instrument, and these magnifying devices carry with them their own inaccuracies, e.
In mechanical system the errors are introduced due to bending of levers, backlash at the pivots, inertia of the moving parts, errors of the threads of screws etc. Probably the wrong geometric design may also introduce errors. Thus the greater the accuracy is aimed at, greater the number of sources of errors to be investigated and controlled.
As regards the instrumental errors, they can be kept as small as possible.
Measuring Instruments | Metrology Institute of the RS
The constant or knowable sources of errors can be determined by the aid of superior instruments and the instrument may metrology measuring instruments calibrated accordingly.
However, an accurate measuring instrument should fulfil the following requirements: Further the measuring metrology measuring instruments performed on the standard and on the unknown must be as identical as feasible and under the same physical conditions environment temperature, etc.
In some instruments, accuracy is expressed as percentage of full scale deflection, i. Thus at lower readings in the range, accuracy may be very poor.
Accuracy in measurement is essential at all stages of product development from research to development metrology measuring instruments design, production, testing and evaluation, quality assurance, standardisation, on-line control, operational performance appraisal, reliability estimation, etc.
The last word in connection with accuracy is that the accuracy at which we aim, that is to say, the trouble we take to avoid errors in manufacture and in measuring those errors during inspection must depend upon the job itself and on the nature of what is required, i. Although local systems of measurement were common, comparability was difficult since many local systems were incompatible.