B&C Technologies DI-225 Industrial - Manual (Page 13)

D. EXHAUST REQUIREMENTS
1. General Exhaust Duct Work Information
Exhaust duct work should be designed and installed by a qualified professional. Improperly
sized duct work will create excessive back pressure which results in slow drying, increased use
of energy, over-heating of the dryer, and shutdown of the burner by the airflow (sail) switches,
burner hi-limits, or basket (tumbler) hi-heat thermostats.
The duct work should be laid out in such a way that the duct work travels as directly as possible
to the outdoors with as few turns as possible. Single or independent dryer venting is
recommended.
The internal dimensions of the dryer’s rectangular exhaust vent work is 12-inches by 20-inches
(304 mm. x 508 mm.).The plant’s exhaust duct must be at least 20-inches (508 mm) in diameter
of for a rectangular duct have cross-sectional areas of 315 square inches (1,549 sq.cm.). The
duct work from the dryer to the outside exhaust outlet should not exceed thirty (30) feet. The
shape of the duct work is not critical so long as the minimum cross-sectional area is provided. It
is suggested that the use of 90 o turns in ducting be avoided; use 45 o angles instead. The radius
of the elbows should preferably be 1-1/2 times the width or diameter of the duct. Excluding
basket/dryer elbow connections used for outside protection from the weather, no more than two
(2) elbows should be used in the exhaust duct run. If more than two (2) elbows are used, the
cross section area of the duct work must be increased.
All duct work should be smooth inside with no projections from sheet metal screws or other
obstruction which will collect lint. When adding ducts, the duct to be added should overlap the
duct to which it is to be connected. All duct work joints must be taped to prevent moisture and
lint from escaping into the building. Inspection doors should be installed at strategic points in the
exhaust duct work for periodic inspection and clean out of lint from the duct work.
IMPORTANT: Exhaust back pressure measured by a manometer in
the exhaust duct should not exceed 0.3 inches of water
column.
NOTE: Where the exhaust duct work passes through a wall, ceiling or
roof made of combustible materials, the opening must be 2
inches larger (all the way around) than the duct. The duct must
be centered within this opening.