Alliance Laundry Systems Drying Cabinet - Manual (Page 27)

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Exhaust Requirements
25 70304601
Individual Venting
For maximum efficiency and performance, it is preferred
to exhaust tumbler(s) individually to the outdoors.
IMPORTANT: At no point may the cross sectional
area of installed venting be less than the cross
sectional area of the exhaust outlet of the tumbler.
The exhaust duct must be designed so the static back
pressure measured 12 inches (305 mm) from the
exhaust outlet does not exceed the maximum
allowable pressure specified on the installation sticker
on the rear of the tumbler.
NOTE: Static back pressure must be measured
with both pockets running.
The maximum allowable length venting of the same
diameter as the exhaust thimble is 14 feet (4.3 m) and
two 90° elbows or equivalent. If the equivalent length
of a duct required for an installation exceeds the maximum
allowable equivalent length, the diameter of a round duct
must be increased by 10% for each additional 20 feet
(6.1 m). Cross section area of a rectangular duct must
be increased by 20% for each additional 20 feet (6.1 m).
Refer to Table 4 to determine equivalent venting.
Example: A 12 inch (305 mm) diameter duct’s
equivalent length of 14 feet (4.3 m) of duct and two
90° elbows is:
Equivalent Length = 14 feet + (2) 90° elbows
= 14 feet + 14 feet + 14 feet
= 42 feet (12.8 m)
With the tumbler in operation, and both pockets
running, airflow at any point in the duct should be at
least 1200 feet per minute (366 meters per meter) to
ensure that lint remains airborne. If 1200 feet per
minute cannot be maintained, schedule monthly
inspections and cleaning of the ductwork.
Duct
Diameter
Equivalent Length of
Straight Duct
10 in. (254 mm)
12 in. (305 mm)
14 in. (355.6 mm)
16 in. (406.4 mm)
18 in. (457.2 mm) One 90° elbow = 11.6 ft. (3.5 m)
One 90° elbow = 14 ft. (4.3 m)
One 90° elbow = 16 ft. (4.9 m)
One 90° elbow = 18.7 ft. (5.7 m)
One 90° elbow = 21 ft. (6.4 m)
Equivalent Length (feet) = 1.17 x Duct Diameter (inches)
Table 4