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Controlling Ventilation Air Flows

Animation Series 1:
Controlling Ventilation Air Flows
  1. Desired Ventilation Flows
  2. Overcrowded Offices
  3. Air Handling Unit Contaminated
  4. Outdoor Air Damper Opening Reduced
  5. Exhaust Not Operating Properly
  6. Supply Air to Office Shut Off or Pinched Down
  7. Economizer Operating
  8. Contaminated Outdoor Air

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Exhaust Not Operating Properly

4. Reducing exhaust air flow has had multiple effects in the office area 3. Because less air is being drawn out of the building through the exhaust 2. When the exhaust air flow was eliminated, the laboratory became positively pressurized 1. Exhaust air flow NEEDS TO BE CHECKED PERIODICALLY. Many factors can account

Mouse over the animated picture above to see messages which are referenced in more detail below.
Pressure relationships between rooms is designated at the bottom of each room (with a plus for positive and minus for negative pressure).

  1. [EXHAUST]  Exhaust air flow NEEDS TO BE CHECKED PERIODICALLY. Many factors can account for inadequate exhaust flow. Exhaust fans may not be operating properly or the building may become depressurized because of inadequate outdoor air or for other reasons. Notice how contaminants have accumulated in the laboratory when the exhaust does not operate properly. What happens to laboratory pressure?

  2. [PRESSURE]  When the exhaust air flow was eliminated, the laboratory became positively pressurized from the supply air.   Now chemical contaminants are more likely to spill out into the offices.
     
  3. [OUTDOOR AIR]  Because less air is being drawn out of the building through the exhaust, the building has a higher atmospheric pressure so that LESS OUTDOOR AIR ENTERS the building. What does this do to the office contaminants?
     
  4. [OFFICE SPACE]  Reducing exhaust air flow has had multiple effects in the office area. Laboratory contaminants spill into the office environment from the laboratory through unintended pathways, and outdoor air which once diluted office contaminants is now reduced. Office pollutants in the office area increase and are joined by laboratory chemicals. Exhaust fans and air flow should be checked periodically to make sure they are functioning properly.

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