PRESSURE

• Pressure (the symbol: P) is the force per unit area applied in a direction perpendicular to the surface of an object.

• Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.

PRESSURE MEASUREMENT

• The measurement and control of fluid pressure is important in process industries.

• Many techniques have been developed for the measurement of pressure.

• A pressure sensor measures pressure, typically of gases or liquids

• A pressure sensor usually acts as a transducer; it generates a signal as a functionof the pressure imposed. For the purposes of this article, such a signal is electrical.

• Pressure sensors are used for control and monitoring in thousands of everyday applications.

• Pressure sensors can also be used to indirectly measure other variables such as fluid/gas flow, speed, water level, and altitude

PRESSURE MEASUREMENT EQUIPMENT

• THE 3 MAIN METHODS OF MEASURING ARE1. LIQUID COLUMN METHODS

Manometer

2. ELASTIC ELEMENT METHODS

Bourdon tubes

Bellows

Diaphragm

3. ELECTRICAL METHODS

Strain gauges

Piezoelectircal tranducers

Piezoresistive transducers

MANOMETER• A Manometer is a device which can be used to measure pressure

of fluids(i.e liquids and Gases). • PRINCIPLE: Manometers are those pressure measuring devices

which are based on the principle of balancing the column of liquid(whose pressure is to be found) by the same or another column of liquid. They are of two types

• 1. simple manometers • 2.Differential manometers • simple manometers are those which measure pressure at a point

in a fluid containing in the pipe or a vessel. On the other hand Differential manometers measure the difference of pressure between any two points in a fluid contained in a pipe or vessel.

APPLICATIONS OF MANOMETER

• Pressure guages are used for a variety of industrial and application specific pressure monitering applications. visual monitering of air and gas pressure for compressors,Vaccum equipment and speciality tank applications such as medical gas cylinders, fire extin

• Liquid column gauges consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. A very simple version is a U-shaped tube half-full of liquid, one side of which is connected to the region of interest while the reference pressure (which might be the atmospheric pressure or a vacuum) is applied to the other. The difference in liquid level represents the applied pressure. The pressure exerted by a column of fluid of height h and density ρ is given by the hydrostatic pressure equation, P = hgρ. Therefore the pressure difference between the applied pressure Pa and the reference pressure P0 in a U-tube manometer can be found by solving Pa − P0 = hgρ. In other words, the pressure on either end of the liquid (shown in blue in the figure to the right) must be balanced (since the liquid is static) and so Pa = P0 + hgρ.