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PRESSURE MEASUREMENT - Coggle Diagram

- - - - The pressure is applied to the bellows
        
        This bellows acts as a transducer element which converts the pressure into a displacements, x.
        
        The displacement x, moved the core and effect the voltage between primary and secondary coils
        
        Finally, the output reading is proportional to the displacement of the core (iron)
- - - - With hydrostatic pressure to accommodate a bulk compression effect
- - - - The Pirani gauge measures the vacuum pressure dependent thermal conductivity from the heated wire to the surrounding gas
      - Advantages
        
        Significantly better resolution in the range above 75 Torr
        
        The power consumption is drastically reduced compared to continuously operated Pirani gauges
        
        The pulsed mode can be efficiently implemented using modern microprocessors.
    - - measure very low pressures, down to 10−6 Torr
      - The working of McLeod Gauge is based on Boyle’s law.
      - pV = pcVc
      - p & V – Pressure and Volume of gas before compression
      - pc & Vc – Pressure and Volume of gas after compression
      - ADVANTAGE
        
        McLeod gauge is an inexpensive standard that measures vacuum pressure without any electronics or sophisticated equipment
        
        The readings obtained from McLeod gauge do not require any correction
    - - Ionization Gauge is a device that is used to measure vacuum. In the hot cathode type, a column of gas is introduced into which, a potential difference V is applied with free electron in the space
      - measure pressure down to about 2 torr
    - - An absolute gauge in the range of 10−8 -10−3 torr
      - Independent of gas composition
      - More suitable for laboratories
- - - - non-corrosive and not have any chemical reaction with the
        fluid which pressure is being measured.
      - low viscosity to ensure quick respond to pressure changes.
      - should have negligible surface tension and capillary effects.
  - - - DIAPHRAGM
      - BELLOWS
      - CORRUGATED DIAPHRAGM
      - CAPSULE
      - BOURDON TUBE
      - HELICAL TUBE