 Fluid pressure measurement | Intensity and Types of pressure

# Fluid pressure measurement | Intensity and Types of pressure

The liquid is such a substance that can flow. When a liquid is in a vacuum container pressure acts vertically on its touchy surface because of not having any sheer stress. This pressure is equal to its surface liquid. If the depth of the liquid is increased, the intensity of the pressure also increases and if the depth of the liquid decreases, the intensity of the liquid decreases. The pressure of the fluid operates different types of hydraulics machine therefore; it becomes mandatory to know the quantity of this pressure. Besides, the discharge of fluid in a pipe or pipe-like way depends on its pressure.

### What is fluid pressure?

The force applied on the surface of any liquid, gas or vapour is called pressure. The force applied by a liquid to the bottom and all points of other sides of a container when water or any kind of liquid is kept in a container is called pressure.

Think,
$$P = Total pressure (kg) \\ A = Total area of surface ( cm) ^{2}\\ P = Pressure of single surface (kg/cm^{2})\\ Here is the point, total pressure, P is expressed in (kg) or (gm) and \\ intensity of pressure is (kg/m^{2}) or (gm/cm^{2})$$

### Intensity of pressure

If any liquid is kept in a container, this liquid applies force to the bottom and all points of all sides of the container. The pressure applied to a single area inside the liquid is called intensity of pressure. Mainly, pressure and intensity of pressure are the same. The difference between total pressure and intensity of pressure is that the pressure works on the total area of a surface is total pressure and the pressure works on a single area is the intensity of pressure. The intensity of the pressure can be expressed to P.

$$Now intensity of pressure =\dfrac {Total pressure (P)}{Area (A)}$$

Total pressure (P)= Intensity of pressure × Area (A)

### Properties of intensity of pressure

• The intensity of pressure is zero on the surface of any liquid and highest on the bottom.
• The intensity of the pressure of a liquid is proportional to its height or depth. It is to say, if the depth of the liquid increases the intensity of pressure is increases, and if depth decreases the intensity of pressure is also decreases.
• The intensity of pressure works equally at any point in every side of the liquid.
• The intensity of pressure is equal in all points of the same horizontal straight line of a liquid.

#### The significance of fluid pressure measurement

The liquid, gas and vapour can be caught in the same phase. Because it is all flowing. That is, they can flow from one place to another. The liquid is fairly not compressible but gas, vapour is compressible. The fluid in these three conditions transported by pipe from one place to another. The amount of flow in this fluid depends on the amount of pressure in the flow path. More pressure can transfer more fluid within less time. Except in case of fluid flow, putting liquid in any container, it presses it vertically on the vessel. The amount of this pressure depends on the height of the fluid in the container. Hydraulic machinery has been invented to exploit this pressure of the fluid flow, Like- hydraulic press, lift, crane, accumulator etc. Therefore, the significance of flow pressure is immense and it is absolutely necessary to measure the intensity of this pressure.

## Types of pressure

The free surface of a liquid

That’s liquid has no pressure on the top surface, in fact, that surface is called free surface. But it can be seen that every liquid has some pressure on its surface. In practical cases, if the liquid does not touch container coverage is called the liquid free surface.

Atmospheric pressure

Atmospheric has weight and because of this weight applied pressure on the ground surface. This pressure of air is called atmospheric pressure. Since air is a compressible substance, That is why the density of the air at different altitudes varies. Moreover, due to temperature and humidity changes the density of the air is seen to change. All of these disadvantages give some complications in determining atmospheric pressure. The instrument with which to measure the air pressure is called a barometer. The average atmospheric pressure at a location along the sea is 1.03 kg per square centimeter, which is water 10.3 meters and mercury 76-centimeter equivalent.

Gauge pressure

The pressure measuring device is a pressure gauge and pressure gauge readings are called gauge pressure. Gauge pressure may be higher or lower than atmospheric pressure. If the gauge pressure is higher than the atmospheric pressure, then it is positive gauge pressure and when it low, it is called negative pressure or vacuum pressure. In the case of vacuum pressure is called vacuum gauge.

Vacuum pressure

Where no substance is found in solid, liquid or gaseous conditions he is called perfect vacuum. That is, that place is completely pressuring free hence known as a complete vacuum. But it is difficult to find a complete vacuum place.

Absolute pressure

The sum of the algebraic sums of ideal air pressure and gauge pressure is called absolute pressure. If the air pressure in a place is higher than the surrounding pressure. However, the difference between those two air pressure is called positive pressure and if less then I would say negative pressure. #### Omar Faruk

I am Omar Faruk, the owner of Engineers Advice. He is a person who always tries to invent something new & share that others. He loves to write about Mechanical, Electrical and Electronics related content. He has completed his diploma from the Department of Mechanical and graduation from the Department of EEE.

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