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| Duct Model Sprinkler System Applications. |
The FMRC Data Sheet 7-78 details sprinkler design recommendations in the section entitled "Industrial Exhaust Systems" Please refer to this report for further information. The following excerpts are taken from this report:
“The need for sprinklers is determined by the combustibility of ducts and contents, size and importance of the duct system, the damage which could result from o fire, and the effects that a fire would hove on production. The protection should be designed to meet the individual conditions. Sprinklers ore usually needed on larger ducts of combustible deposits accumulate, and in housing or impeller casings of large and important fans.”
"Install sprinklers in all ducts which have cross-sectional areas greater than or equal to 100 sq. in. (645 sq cm) or which have diameters greater than or equal to 12 in. (305 mm), and which:
a. are combustible (unless specifically FMRC-Approved) for plastic ducts carrying noncombustible fumes, or;
b. have a combustible interior lining greater than 30 mils (0.8 mm) thick (6 mils, 0.1 mm thick in occupancies susceptible to smoke damage), or;
c. carry combustibles sufficient to cause a damaging fire.
Sprinklers should also be provided in smaller ducts which offer serious exposures.”
“For ducts described in No. 2.4.2 above, install sprinklers as follows:
a. Sprinklers should be spaced on not over 12 ft. (3.7m) o.c. in horizontal or vertical ducts.
Sprinkler temperature rating should be at least 50 F (27 C) above the temperature of the
environment handled by the duct.
b. When the duct width or diameter is over 12 ft. (3.7 m), provide additional lines of automatic sprinklers 12 ft. (3.7 m) o.c.
c. In systems with branched ducts, one sprinkler should be provided in each branch duct regardless of its size within 3 ft. (0.9 m) of its point of entry into a main duct system. Several smaller ducts may be manifolded and a single sprinkler provided before the manifold entry into the main duct system."
Sprinklers should be readily accessible for inspection.
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