SENSORS


This Blog is made so that the students and engineers get the basic knowledge on the various types of sensor technologies available. This blog contains information on the working of various kinds of sensors, their advantages, disadvantages, common applications and links of best manufacturers.

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Air Compressor


What is Air compressor and how Air compressor works

An air compressor is a device that converts power usually from an electric motor, a diesel engine or a gasoline engine into kinetic energy by compressing and pressurizing air, which can be released in quick bursts. 

Different types of Air compressors

  • Reciprocating compressor
  • Rotary screw compressor
  • Rotary vane Compressor
  • Centrifugal compressor
According to the number of stages the compressor can be divided as
  • Single stage compressor
  • Multi stage compressor

What is a Reciprocating compressor and how Reciprocating compressor works

Reciprocating compressors are positive displacement compressors and can be found in ranges from fractional to very high horse powers. It works by filling an air chamber with air and then reducing the chamber’s volume. Reciprocating compressors work in a very similar manner as internal combustion engine but basically in a reverse process. They have cylinders, pistons, crankshafts, valves and housing blocks. These compressors are the most commonly found compressors on portable air compression units.

Advantages of Reciprocating Compressor
  • Easy to install
  • Simple design
  • Lower cost
  • Large range of horse power
  • Can reach high pressures
  • High efficiency for two stage compressors
Disadvantages of Reciprocating Compressor
  • Higher maintenance cost
  • Potential for vibration problems
  • Many moving parts

What is a Rotary screw compressors and how Rotary screw compressor works

Rotary screw compressors use two meshing helical screws known as rotors to compress the gas. As the two helical screws are turned the volume is reduced. This results in an increase in air pressure. In an oil-flooded rotary screw compressor lubricating oil bridges the space between the rotors. This results in a hydraulic seal and transferring mechanical energy between the driving and driven rotor. Air enters at the suction side and moves through the threads as the screws rotate. The meshing rotors force the air through the compressor and the gas exits at the end of the screws. After the compression cycle, the air and the oil must be separated before air can be used by the air system.

Advantages of Rotary screw compressors
  • Simple design and easy installation
  • Low cost
  • Fewer moving parts
Disadvantages of Rotary screw compressors
  • Shorter life than other types
  • Single stage designs may have lower efficiency

What is Rotary Vane Compressors and how Rotary Vane Compressors works

Rotary Vane Compressors are positive displacement compressors. The pump consists of a rotor, stator, and blades. The number of blades could be ranging from 8 to 12. The slotted rotor is arranged within the stator providing a crescent shaped swept area between the intake and exhaust ports. As the rotor turns a single revolution, compression is achieved as the volume goes from a maximum at the input and minimum at the output.

Advantages of Rotary Vane Compressors
  • Simple design and easy to install
  • Since a rotary vane does not operate at close tolerances, it's life expectancy exceeds those compressor designs that depend on close tolerance
  • Low cost
  • Fewer moving parts
Disadvantages of Rotary Vane Compressors
  • Single stage designs may give lower efficiency
  • Not recommended for high pressures

What is Centrifugal Compressors and how Centrifugal Compressors works

Centrifugal Compressors are not positive displacement compressors like the Reciprocating, Screw or Vane Compressors. Centrifugal compressors use a rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser section converts the velocity energy to pressure energy. These machines have inter coolers between each stage to cool the air as well as remove 100% of the condensate to avoid impeller damage due to erosion.

Advantages of Centrifugal Compressors
  • Can give high pressures
  • Lubricant free air
Disadvantages of Centrifugal Compressors
  • High cost compared to other types
  • Large frontal area for given airflow