37
Rev. 2
COMBUSTION AND VENTILATION AIR
5.3.4 Specially Engineered Installations:
The requirements of 5.3.3 shall not necessarily govern when
special engineering, approved by the authority having juris-
diction, provides an adequate supply of air for combustion,
ventilation, and dilution of flue gases.
5.3.5 Louvers and Grilles:
In calculating free area in 5.3.3, consideration shall be given
to the blocking effect of louvers, grilles or screens protecting
openings. Screens used shall not be smaller than 1/4 inch
mesh. If the area through a design of louver or grille is known,
it should be used in calculating the size of opening required
to provide the free area specified. If the design and free area
is not known, it may be assumed that wood louvers will have
20-25 percent free area and metal louvers and grilles will
have 60-75 percent free area. Louvers and grilles shall be
fixed in the open position or interlocked with the equipment
so that they are opened automatically during equipment
operation.
5.3.6 Special Conditions Created by Mechanical Ex-
hausting or Fireplaces:
Operation of exhaust fans, ventilation systems, clothes dry-
ers, or fireplaces may create conditions requiring special
attention to avoid unsatisfactory operation of installed gas
utilization equipment.
Содержание GCIA045A30
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