TRANSDUCERS & ITS INDUSTRIAL APPLICATIONS

PRESENTED BYAJAY KUMAR

ROLL NO. 1305232005E.I ,III YEAR

TYPES OF TRANSDUCERS

PRESSURE MEASUREMENTTEMPERATURE MEASUREMENTFLOW MEASUREMENT

FlOW MEASUREMENT

• ORIFICE PLATE • VENTURI TUBE • ROTAMETER

Differential Pressure FlowmetersThe Orifice Plate

• The orifice plate is the simplest and cheapest. It is simply a plate with a hole of specified size and position cut in it, which can then clamped between flanges in a pipeline

• The increase that occurs in the velocity of a fluid as it passes through the hole in the plate results in a pressure drop being developed across the plate.

• After passing through this restriction, the fluid flow jet continues to contract until a minimum diameter known as the vena contracta is reached.

The Venturi Tube

• The classical or Herschel Venturi tube is the oldest type of differential pressure flowmeter (1887).

• The restriction is introduced into the flow in a more gradual way• The resulting flow through a Venturi tube is closer to that predicted in theory so

the discharge coefficient C is much nearer unity (0.95). • The pressure loss caused by the Venturi tube is lower, but the differential pressure

is also lower than for an orifice plate of the same diameter ratio.

• The smooth design of the Venturi tube means that it is less sensitive to erosion than the orifice plate, and thus more suitable for use with dirty gases or liquids.

• The Venturi tube is also less sensitive to upstream disturbances, and therefore needs shorter lengths of straight pipework upstream of the meter than the equivalent orifice plate or nozzle.

• Like the orifice plate and nozzle, the design, installation, and use of the Venturi tube is covered by a number of international standards.

• The disadvantages of the Venturi tube flowmeter are its size and cost.

The Venturi Tube