MECHANICAL MEASUREMENTS


A

(a)

Precision

(b) Repeatability

Explain systematic and random errors.

List any five major transducer characteristics.

Explain Circular Bourdon tube actuating mechanism with a neat sketch.

Explain with a neat sketch Diaphragm type pressure gauge.

Explain with neat sketch the working of strain gauge type load cell.

Explain with sketch the principle of working of thermocouple.

Explain with a neat sketch Hydrometer.

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Differentiate between Unilateral and Bilateral tolerance.

10.

PART-B

(a) Draw a neat sketch of Bevel protractor and label its parts. Explain with a neat sketch Ring gauge.

(b)

11. (a) Explain with neat sketch Talysurf surface roughness tester. (b) Explain with a neat sketch CMM.

12.

(a) Explain with neat sketch the working principle of optical strain gauge. (b) State any three transducer selection factors.

13

(a) Explain with a neat sketch prony brake dynamometer.

(b) Define pressure. List any three pressure measuring instruments.

14.

Explain with a neat sketch LVDT. (b) List any three advantages of Resistance thermometer.

(a)

15.

3

5

5

(a) Explain with a neat sketch optical pyrometer. (b) Classify the various Tachometers.

16.

5

(a) Explain the working of Hair hygrometer with a neat sketch.

(b)

(b) Explain with neat sketch liquid level measurement by using sight glass.

17. (a) Explain with a neat sketch plezo-electric transducer.

(b) State any three advantages and two disadvantages of mechanical strain gauge.

18.

Define:

(a) Explain with a neat sketch hole basis system and shaft basis system. (b)

6

(i) Limit

(ii) Allowance

(iii) Basic size

(iv) Tolerance

19.

(a) Explain with neat sketch procedure for checking the parallelism of spindle to carriage movement in lathe. (b) List the various types of testing equipments used for m/c tool alignment test.

 

  1. a) Define accuracy and sensitivity of an instrument.     [4]           b) What is static sensitivity?              [3]
    1. Define (i) atmospheric pressure (ii) gauge pressure and (iii) absolute pressure. [3]
    2. Enumerate advantages and applications of strain gauges.         [4]
    3. Explain the working of liquid in glass thermometer. [4]
    4. What are the desirable properties of materials used in resistance thermometers?       [4]

 

                                                   PART–B (3x16 = 48 Marks)               

  1. a) Explain the elements of a generalized measurement system. [8]  b) A Bourdon pressure gauge having a linear calibration has a 50 mm long pointer.  It moves over a circular dial having an arc of 270˚. It displays a pressure range of  0 to 15 bar (1 bar = 105 Pa). Determine the sensitivity of the Bourdon gauge in  terms of scale length per bar (i.e., mm/bar). [8]

                              

  1. a) Explain different static performance characteristics of an instrument.               [8]       b) Explain about different data display and storage systems.           [8]

                              

  1. a) Explain the working of well-type manometer with a neat sketch. [8] b) A McLeod pressure gauge has volume of bulb V=100×10-6 m3 and measuring  capillary diameter of 1mm.Calculate the pressure indicated when the reading of  the measuring capillary is 30 mm in case approximate formula is used. What is  the error if the exact formula is used for measurement of pressure?  [8]

                              

  1. a) A bridge circuit has two fixed resistors and two strain gauges all of which have a value of 120 Ω. The gauge factor is 2.04 and strain applied to twin strain gauges,  one in tension and the other in compression is 165×10-6. If the battery current is  50 mA, determine the (i) voltage output of the bridge, (ii) the sensitivity in volt  per unit strain. If the galvanometer connected to output terminals reads 100µV  per scale division and if 1/10th of a division can be read with confidence,  determine the resolution.           [8]  b) Derive an expression for gauge sensitivity of a strain gauge for measurement of  strain on account of force acting on a cantilever using one active strain gauge in 

Wheatstone bridge.   [8]      

  1. a) Explain the classification of temperature measuring devices. [8] b) A bimetallic strip is constructed of strips of yellow brass and Invar bonded  together at 30˚C. Each has a thickness of 0.3 mm. Calculate the radius of  curvature when a 60 mm strip is subjected to a temperature of 100˚C. One end of  the bimetallic strip is fixed. The thermal coefficient of expansion of yellow brass  and Invar are respectively 20.2×10-6/˚C and 1.7 ×10-6/˚C and their modulus of  elasticity are respectively 96.5 GN/m2 and 147 GN/m2. [8]

                                     

  1. a) Two machines are working in noisy environments. The background noise when the machines are inoperative is 65 dB. If the two machines having individual  sound pressure levels of 84 and 88 dB are switched on simultaneously, determine  the combined sound pressure level of the machines along with the background      [8]
  2. b) Explain the working of linear variable differentiation transformer (LVDT) for                                                           

displacement measurement.