MEASUREMENT OF PRESSURE

MEASUREMENT OF PRESSURE. 

          The pressure of a fluid is measured by the following devices :

1. Manometers 

2. Mechanical Gauges 

1. MANOMETERS. 

              Manometers are defined as the devices used for measuring the pressure at a point in a fluid by balancing the fluid column by the spring or dead weight. The commonly used mechanical pressure gauges are : 

 (a) Diaphragm pressure gauge, 

 (b) Bourdon tube pressure gauge, 

 (c) Dead -weight pressure gauge, and 

 (d) Bellows pressure gauge. 

SIMPLE MANOMETERS. 

            A simple manometer 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. Common types of simple manometers are : 

(1) Piezometer, 

(2) U -tube Manometer, and

(3) Single Column Manometer. 

(1) PIEZOMETER. 

              It is the simplest form of manometer used for measuring gauge pressures. One end of this manometer is connected to the point where pressure is to be measured and other end is open to the atmosphere as shown in figure. The rise of of liquid gives the pressure head at that point. If at a point A, the height of liquid say water is h in piezometer tube, then pressure at A

                           =  ⍴ × g × h  N/m²

Piezometer

(2)  U -tube Manometer. 

                        It consists of glass tube bent in U-shape, one end of which is connected to a point at which pressure is to be measured and other end remains open to the atmosphere as shown in figure. The tube generally contains mercury or any other liquid whose specific gravity is greater than the specific gravity of the liquid whose pressure is to be measured. 

(a) For Gauge Pressure. 

(a) For gauge pressure

For gauge pressure

(b) For Vacuum Pressure. 

(b) For vacuum pressure

For vacuum pressure

                                    The End. 

    Please comment if you have any query.


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