Selection of An Air Curtain
To determine the required protection, measure the door-draft due to
negative pressure. To this figure add 1/3 of the prevailing wind and add a safety factor
of 20%. (see charts for numbers)
This gives the required protection to:
(2 + 12.1/3) x 1.20 =7.24
The required protection for this door is 7.24 mph. In the chart
below select the line representing the required air throw.
- Half of the door width for an installation with an Air Curtain mounted on both sides of
the doorway.
- The door height for an Air Curtain mounted overhead.
- The door width for an Air Curtain mounted vertically on one side only.
If the negative pressure in the building is excessive it should be relieved by some
means such as:
- A make-up air unit, possibly combined with the Air Curtain.
- A relief opening in the building.
An Air Curtain alone is not a cure for all excessive negative pressure. Make-up air
should be added and the most comfortable, practical and economical way is through an Air
Curtain.
