Fluid pressure and measurements1112.pptx

Besides tonal audiometry, it is sometimes necessary to carry out tests with spoken voices.
These tests are particularly important before prescribing hearing-aids and in determining the
deterioration of speech understanding of patients. Specially designed speech audiometers are
used for this purpose. They incorporate a good quality CD player, which can play recorded
speech. Masking noise is supplied by the noise generator. The two channels supply the two headphones
or
the
two
loudspeakers.

The
CD
player
has
a
capacity
for
recording
a
limitless
variety
of
test
material
and
a
consistency

of

speech input, which cannot be obtained for live-voice audiometry in relation to test-retest
repeatability. Another advantage of the recorded material is that the test words and sentences can
be selected to cater for the widely differing needs of age, intelligence, dialect and language.
In speech audiometers,
live-voice facilities are
incorporated primarily for
communicationpurposes as the inherent unreliability of live-voice speech tests may lead to
serious errors.
The microphone amplifier used for this purpose is a simple two stage amplifier.
The frequency response characteristics of a live-voice channel should be such that with the
microphone in a free sound field having a constant sound pressure level

1. 23MT403 – FLUID AND THERMAL ENGINEERING Topic: Fluid pressure and measurements – Piezometer, U-tube manometer and U-tube differential manometer Faculty: Dr.D.PRITIMA

2. Pressure: Pressure is defined as a normal force exerted by a fluid per unit area. Units: N/m 2 , bar, Pa, kPa, mm of Hg and mm of water

3. Barometer: Used to measure atmospheric pressure.

5. 1. A hydraulic press has a ram of 30 cm diameter and a plunger of 4.5 cm diameter. Find the weight lifted by the hydraulic press when the force applied at the plunger is 500 N.

6. 2. An open tank contains water upto a depth of 2 m and above it an oil of sp. Gr. 0.9 for a depth of 1 m. Find the pressure intensity (i) at the interface of the two liquids, and (ii) at the bottom of the tank.

8. Pressure relationships:  

9. Measurement of pressure: Manometers: Used for measuring the pressure at a point in a fluid by balancing the column of fluid by the same or another column of the fluid. (a) Simple Manometers (b) Differential Manometers 2. Mechanical Gauges: Used for measuring the pressure by balancing the fluid column by the spring or dead weight. (a) Diaphragm pressure gauge (b) Bourdon tube pressure gauge (c) Dead-weight pressure gauge (d) Bellows pressure gauge

10. Fluid pressure and measurements (a) Simple Manometers: It consists of a glass tube having one of its ends connected to a point where pressure is to be measured and other end remains open to atmosphere. Piezometer U-tube Manometer Single Column Manometer

13. 1. The right limb of a simple U-tube manometer containing mercury is open to the atmosphere while the left limb is connected to a pipe in which a fluid sp. gr. 0.9 is flowing. The centre of the pipe is 12 cm below the level of mercury in the right limb. Find the pressure of fluid in the pipe if the difference of mercury level in the two limbs is 20 cm.

14. 2. A simple U-tube manometer containing mercury is connected to a pipe in which a fluid of sp. gr. 0.8 and having vacuum pressure is flowing. The other end of the manometer is open to atmosphere. Find the vacuum pressure in pipe, if the difference of mercury level in the two limbs is 40 cm and the height of fluid in the left from the centre of pipe is 15 cm below.

16. (b) Differential Manometers: It used for measuring the difference of pressures between two points in a pipe or in two different pipes. U-tube differential Manometer Inverted U-tube differential Manometer

17. U-tube differential Manometer ( two pipes are at different levels) Consists of a U-tube, containing a heavy liquid.  

18. U-tube differential Manometer ( two pipes are at same level)  

19. 1. A pipe contains an oil of sp. gr. 0.9. A differential manometer connected at the two points A and B shows a difference in mercury level as 15 cm. Find the difference of pressure at the two points.

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