Alternate suppression systems

In certain applications, water may not be the most effective means to extinguish fires. In fact, in special cases, water could actually transport fire. Hence, the Uniform Fire Code allows alternate suppression systems. In some cases, the use of an alternative suppression system will not preclude the need to install water sprinklers. UPC 8003.3.1.2 does not permit use of alternate systems for HPM storage areas, gas cabinets, or exhausted enclosures. 

There are three classifications of backup systems to the normal electrical power system in hazardous occupancies  

All industrial occupancies shall have emergency lighting in accordance with NFPA Section 5-9 (NFPA 101 28-2.9). 

An emergency power system shall be provided in Group H, Divisions 6 and 7 Occupancies to automatically supply power to the exhaust ventilation system when the normal electrical supply system is interrupted (UBC 307.2.8). Only exhaust is required to be on emergency power however, the exhaust must be balanced with makeup air and, thus, some supply fans may also require emergency power, particularly in the case of critical clean-rooms. Refer to section on HVAC systems for further discussion). 

Generally, the size of an emergency generator is dictated by the starting current requirements of large fan motors for the cleanroom ventila- 

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Alternatives to Arresters Alternatives to the use of flame arresters include fast-ac ting isolation valves, vapor suppression systems, velocity-type devices in which gas velocity is designed to exceed flashback velocity, and control of the flammable mixture (NFPA 69 standard, Explosion Prevention Systems ). The latter alternative frequently involves reduction of oxygen concentration to less than the limiting oxygen concentration (LOC) of the gas stream. 

Alternatives to Arresters Alternatives to the use of flame arresters include fast-acting isolation valves, vapor suppression systems,... 

Systemic corticosteroids The combined administration of alternate-day systemic prednisone with these products may increase the likelihood of HPA suppression. 

Open systems use atmospheric air for drying. In cases where products pose a potential for dust explosion, plants are provided with pressure relief or suppression systems. For recycle systems, the drying system medium is recycled, and the evaporated solvent recovered as condensate. There are two alternative designs. In the self-inertizing mode, oxygen content is held below 5 percent by combustion control at the heater. This is recommended for products with serious dust... 

R. G. Gann, (ed.) Fire suppression system performance of alternative agents in aircraft engine and dry bay laboratory simulations, NIST SP 890, National Institute of Standards and Technology, Gaithersburg (1995). 

Halon is a generic name for halogenated agents used in fire suppression systems. Until recently, two varieties, Halon 1301 and Halon 1211 were the agents of choice as alternatives to water systems where damage to equipment was a problem. Halon 1301 especially was a desirable alternative because of its low toxicity and effectiveness in low concentrations so that it could be used safely in occupied areas. The different numbers in the nomenclature correspond to the number of carbon atoms, fluorine atoms, chlorine atoms, and bromine atoms in that order in the compound If there were a fifth number in the designation, it would refer to the number of iodine atoms. Halon 1301 is the one most commonly used in occupied spaces while Halon 1211 apphcations are typically in storage areas or other areas which are rarely or sporadically occupied. 

Designing plant safety systems so that redundant safety equipment is protected by automatic fire suppression systems and separated from each other and from other plant areas by fire barriers such that a fire would not endanger other safety related equipment required for safe shutdown. Alternate or dedicated shutdown capability should be provided where the protection of safety systems required for safe shutdown is not provided by established fire suppression methods. 

Safety-related equipment, safeguards, and possible alternative approaches (e.g., monitoring, interlocks, system redundancy, hardware or software fail-operational/fail-safe design considerations, subsystem protection, fire detection/suppression systems, personal protective equipment, ventilation, and noise or radiation attenuation)... 

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