Pressure Measurement Basics

Pressure measurement is critical in every plant where to know the amount of applied pressure is essential. the force applied per unit of area is called pressure,

P = F/A

pressure measurement is done in many ways but before going through different types let find about basic of pressure measurement.

Pressure Measurement

  1. Absolute pressure - Absolute pressure is the total pressure present in the system. Absolute pressure is the pressure measured with respect to zero pressure (vacuum). in the simple term you can say that,

              absolute pressure = gauge pressure + atmospheric pressure
    
  2. atmospheric pressure - the pressure exerted due to atmospheric pressure which is present in our surroundings which is close to 1 bar or 14.7 psi is known as atmospheric pressure.

  3. gauge pressure - pressure measured above 1 psia or atmospheric pressure is called gauge pressure.

  • now let consider some other terms which are also useful,
  1. vacuum - a negative pressure or pressure below atmospheric pressure is called a vacuum.

  2. absolute zero pressure - pressure which is equal to 760 mm Hg of vacuum(-760 mm Hg or around 1 kg).

  • now we will discuss the primary element which used to measure pressure are,
  1. Diaphragm - which is a circular or square-shaped rubber material used in low-pressure applications.

  2. The burden tube - burden tube is used to measure in the high-pressure applications where pressure can be applied up to 7000 bars.

  3. capsule - two circular diaphragms welded together to form capsule.capsule is used to measure air and gases at low pressure up to 0.6 bar

  4. Bellows - bellows are made of seamless folded and thin metal used mostly in beverages where to maintain the quality of the product is essential. bellows types of pressure gauge are used in high-pressure measurement application pressure up to 40 mm Hg.

  5. pressure spring - which comes in helical or spiral shape like normal spring which is also used in high-pressure applications.

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