American Dryer Corp. AD-400 - Manual (Page 19)

f ,
The duct work must be smooth on the inside with no projections from sheet metal screws or other
obstructions which will collect lint. Inspection doors must be installed at strategic points in the duct work
for periodic lint removal.
Use smooth sweeping elbows instead of sharp 90-degree elbows. The radius of an elbow should be at
least 1-1/2 times the duct diameter.
When the exhaust duct goes through a combustible wall on a roof, leave a 2-inch clearance space between
the exhaust ducting and the wall or roof.
When adding ducts, the duct to be added should overlap the duct to which it is to be connected. This will
allow for smoother airflow.
The end of the duct that leaves the building must be protected from the weather. For horizontal ducting,
use a 90-degree turn down and for vertical duct work, use a 180-degree turn down. In either case, allow
at least twice the diameter of the duct between the duct opening and nearest obstruction. (If the duct is
rectangular, leave twice the smallest face dimension.)
WALL
INSPECTION
DOOR
HORIZONTAL EXHAUST DUCT
( IMPORTANT; Do not use screens or caps on the outside opening of the exhaust duct work.
Screens will clog with lint and caps will restrict the exhaust airflow.
5. Fresh Air Supply
The dryer takes 4,500 cfm of air from the room, heats it, draws it through the basket, and exhausts it out
of the building. This 4,500 cfm of air must be replenished in the room for the dryer to operate properly.
An inadequate fresh air supply will lead to increased drying times and unsafe operating conditions.
17