Mechanical Measurement : Metrology

Mechanical Measurement :

It is the act or result of a quantitative comparison between in a predetermined ( predefined ) standard and a unknown magnitude .

If the result is meaningful then following condition must satisfied -

1. The standard must be accurately known and internationally accepted .
2. The appratus and the experimental procedure adopted for comparision must be acceptable .

In short the measurement which is relative to measurement engineering velocity , light , acceleration , pressure and temperature .

Method of Measurement :

There are two method.

1. Primary or directory comparison 
2. Secondary or Indirect comparison

• A direct comparision with the primary or the secondary standard .
• An Indirect comparision through a calibrated system .

Mode of measurement :

1. Primary measurement
2. Secondary measurement
3. Tertiary measurement

1. Primary measurement :

A primary measurement is that which can be made by direct observation  without involving any conversion of the measured quantity in this the observer can see or sense the change directly.

 example- The matching of length, the matching of two colours.

 when the measurement is transmitted to the brain in the form colour variation, light intensity by another sense.

2. Secondary measurement :

It involved only one conversion  to be done on the quantity under measurement.

 example :

1. Pressure- gauge manometer

2.Temperature -  mercury in glass thermometer.

3. Tertiary measurement :

A tertiary measurement involved two conversion to be done on the quantity under measurement.

example :

1. Thermocouple

2. Boundon pressure gauge 

3.Tachometer.

Coming soon