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FLOW MEASUREMENT DEVICES

FLOW MEASUREMENT DEVICES. INTRODUCTION. ORIFICEMETER MOUTHPIECES NOTCHES VENTURIMETER. ORIFICEMETER. ORIFICE-PLATE. ORIFICEMETER. INTRODUCTION. It consists of flat circular plate which has a circular hole, in concentric with the pipe. This is called orifice.

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FLOW MEASUREMENT DEVICES

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  1. FLOW MEASUREMENT DEVICES

  2. INTRODUCTION • ORIFICEMETER • MOUTHPIECES • NOTCHES • VENTURIMETER

  3. ORIFICEMETER

  4. ORIFICE-PLATE

  5. ORIFICEMETER

  6. INTRODUCTION • It consists of flat circular plate which has a circular hole, in concentric with the pipe. This is called orifice. • The diameter of orifice is generally 0.5 times the diameter of the pipe (D), although it may vary from 0.4 to 0.8 times the pipe diameter.

  7. Vena- Contracta The maximum contraction takes place at a section slightly on the downstream side of the orifice. Such a section is known as Vena- Contracta.

  8. ORIFICEMETER • Reduction of cross-section of the flowing stream in passing through orifice increases the velocity head at the expense of pressure head • Reduction of pressure between taps is measured using manometer • Formation of Vena- contracta- Fluid stream separates from the downstream side of the orifice plate and forms a free-flowing jet in the downstream side. • Orifice coefficient, generally, is 0.61

  9. ADVANTAGES • Low initial cost • Ease of installation and replacement • Requires less space

  10. DISADVANTAGES • More pressure loss • Low value of Coefficient of discharge • Susceptible to inaccuracies resulting from erosion, corrosion etc. • Tends to clog so not suitable for slurries

  11. FACTORS AFFECTING LOCATION OF VENA CONTRACTA • Reynolds number • Area ratio b/w orifice and pipe • Roughness of pipe

  12. FACTORS AFFECTING DISCHARGE COEFFICIENT • Type of orifice • Ratio of orifice diameter to pipe diameter • Reynolds number • Location of pressure connections

  13. NUMERICAL PROBLEM Q. An orifice plate of orifice diameter 10 cm has been fitted into a 25 cm diameter pipe that conveys oil of specific gravity 0.8. the pressure differential on the two sides of the orifice plate is measured by a mercury-oil

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