Types Of Ventilation

Health Hygiene & Sanitation

Lesson 15 : Ventilation

Types Of Ventilation

  • Natural ventilation

    • Wind
    • Inequality in temperature

  • Mechanical/ Artificial ventilation

    • Exhaust ventilation
    • Plenum ventilation
    • Balanced ventilation

  • Air conditioning

Natural Ventilation

  • Simplest system of ventilating

  • Reliance is placed on natural factors

  • Wind:

    • Perflation: blow of wind
    • Aspiration: suction force generated at the tail of wind around an obstruction
    • Cross ventilation: presence of door/ windows opposite to each other

  • Diffusion: when air passes through small openings. It takes long time for enough air to pass, so it can’t be relied up on.

  • Inequality in Temperature:

    • Air gets lighter density when heated and heavier density when cooled.
    • Hot air moves up and cold air comes down and these generate ventilation

  • Advantages:

    • Less cost
    • Simplest system
    • With proper location, it can be utilised properly
    • Disadvantages
    • Not possible to regulate the velocity of the incoming air
    • Not possible to regulate the temperature or humidity

Mechanical/ Artificial Ventilation

  • Exhaust Ventilation:

    • Air is extracted to the outside by exhaust fans
    • Exhausted air creates a vacuum which induces fresh air to enter the room through windows/ doors
    • Speed can be adjusted using the fans
    • Local exhaust ventilation is used to remove dust and gases at their source of origin

  • Plenum Ventilation:

    • Air is blown to the INSIDE by centrifugal fans
    • Propelled air creates a positive pressure which displaces vitiated air
    • This system is of limited utility

  • Balanced Ventilation

    • Combination of both exhaust and plenum
    • Both should match and balance to maintain suitable ventilation

Air conditioning

It is the simultaneous control of all or at least the FIRST THREE

  • Temperature
  • Humidity
  • Air movement
  • Distribution
  • Dust
  • Bacteria
  • Odors
  • Toxic gases
  • Air conditioning

    • Is particularly useful in operation theatres etc where strict control of air ensures less infections
    • Air is filtered when drawn into an air-conditioner system from the room
    • Excess humidity is removed, and excess air is re-circulated back into the room by adjusting the temperature
    • Some percentage of fresh air is mixed with conditioned air

  • Central Air conditioning

    • Central air conditioning as employed in bigger hospitals etc is both economic and can be better regulated
    • When the temperature between outside and inside is too high, a transition room to adjust before being exposed to excess difference in temperature.
Last modified: Tuesday, 24 April 2012, 5:28 AM