Sprinklers below

Some authorities having jurisdiction require sprinklers below the operating floor even when the plenum is 2 or less. This is not a proven practice. Tests were performed in Europe to determine the acceptability of sprinklers below computer room floors. They proved to be ineffective and much better protection was provided by gaseous extinguishing systems. There is a fine line between when sprinklers or a gaseous extinguishing system should be provided below the operating floor. It depends on the clearance, obstructions, accessibility and continuity of combustibles. 

Design ventilation system to keep flammable concentration below lower flammable limit Provide on-line flammable gas detection and activation of inerting system Install automatic sprinkler system Install deflagration vents... 

The 2009 edition of the IFC contains requirements for installation of residential sprinklers in all new one- and two-family dwellings and townhouses, effective from January 2011. This is a brand new requirement and is parallel to what is also required (see below) in NFPA 101 and NFPA 5000. It also contains requirements for installation of carbon monoxide detectors. 

Eggleston, Herrera, and Pish 1976 To provide needed data about the use of air entrained by a water spray to dilute flammable vapor releases below the lower flammability limit. Absorption/adsorption effects are insignificant in the case of ethylene and vinyl chloride. Sprinklers and water-spray nozzles vary widely in their efficiency as air movers. Flame quenching was not affected in any of the experiments Water sprays increased the rate of flame propagation. The air-pumping action of a water curtain can be used to set up a barrier to the horizontal flow of vapors. 

Citrus trees are very susceptible to cold weather, and extended e.xposure to subfreezing temperatures can destroy the Crop. In order to protect the trees from occasional cold fronts with subfieezing temperatures, tree growers in Florida usually install water sprinklers on the trees. WOien the tenipeiature drops below a certain level, the sprinklers spray water on the trees and their fruits to protect them against the damage the subfieezing temperatures can cause. Explain the basic mechanism behind this protection measure and write an essay on how the system works in practice. 

The primary use of bismuth metal is in making alloys. Many bismuth alloys have low melting points. The metal itself melts at 520°F (271°C), but some bismuth alloys melt at temperatures as low as 160°F (70°C). This temperature is below the boiling point of water. These alloys are used in fire sprinkler systems, fuel tank safety plugs, solders, and other applications. 

NFPA 30, 4.4.3.9 29CFR1910.106(d)(5) (vi)(e) 4.3.8 No stack of flammable or combustible liquids shall be closer than 3 ft. to the nearest beam, chord, or other construction, and shall be 3 ft. below sprinkler deflectors, discharge orifices of water spray, or other overhead fire protection systems. 

Zones 2 and 3 of the HCF are protected by an automatic wet-pipe sprinkler system. The sprinkler system is designed for Ordinary Hazard Group 2 occupancy. Therefore, this system will be able to accommodate any unforeseen increases in ordinary combustible loading. The HCF is below grade and will contain any firefighting water used. It is also equipped with heat... 

The system comprises a series of water mains, usually overhead, to which sprinkler heads are fitted at intervals. As heat from the fire reaches them individual sprinkler heads operate at predetermined temperatures releasing a deluge of water over the fire below. The advantages of sprinkler systems are, that as only the heads in the vicinity of the fire operate, water damage is reduced to a minimum, they are automatic in operation, they are not impaired by smoke or fumes and are not hindered by the blockage of access routes. 

Four types of sprinkler systems are available wet-pipe, dry-pipe, alternate and pre-action. A wet-pipe system can only be used in premises not subject to frost or ambient temperatures above 70 C. A dry-pipe system is only suitable in premises subject to continuous temperatures below 0 C or above 70 C. An alternate system which enables either wet or dry operation to be selected is suitable in premises subject to freezing during cold weather. Finally a pre-action system, which is a system with a separate heat or smoke detector that allows water into the sprinkler pipework before the first head operates, should only be used where none of the others is suitable. 

Sprinkler heads should be fitted no closer than 75-100 mm below the ceiling or roof and a clear space of at least 750 mm should be maintained between the deflectors and the top of any product or goods being protected. The heads should have a minimum separation of 2 m and be spaced such that no part of the area beneath which needs to be protected remains un wetted. 

Diversion of flow safely All the above systems discussed are part of electronic system requiring power. As a next layer of protection there are mechanical devices (requiring no power to meet power failure situations) to divert the flow safely. Safety and relief valves are used to in case to depressurize when SIS fails to take care (e.g., say due to control power failure). Pressure relief valve diverts the fluid for safe passage. These relief valves are spring force to close so that when pressure is below setting it is closed. Many cases rupture discs are used but in that case system needs to be closed to attain the disc. To a certain extent quartz bulb in sprinkler system does the same function. 

Rainfall for April-August was 7.8 and 22.6 cm below normal (57 cm) in 1992 and 1993, respectively. June of 1993 was so dry that plots were irrigated (2.5 cm) with an overhead sprinkler system to prevent the loss of the experiment. Although locations of treatment plots each year were chosen at random there may have been differences due to cover crop carry-over from 1 year to the next since the experiments for the 2 years were carried out in the same field. For example the soil nitrate-N levels for clover no-till plots in 1993 (mean values from 22 to 50 xg/g soil) were considerably higher than for the 1992 plots (mean values from 5 to 9.5 p,g/g soil Blum et al. 1997). 

For Test 15, the sprinklers had a k-factor of 14 gpm/psi and were installed 14 inches below the ceiling. A nominal operating pressure of 75 psig provided a discharge of 120 gpm per sprinkler. The sprinklers were installed on 10-foot by 10-foot spacing, resulting in a significant density of 1.2 gpm/ft. ... 

Is proper clearance maintained below sprinkler heads ... 

An external fire protection system may have to be adapted to the geometry of a spray dryer. Sprinklers should be applied directly to the dryer, on the head or below the air diffuser plate. They may also be required below a supporting skirt. The temperature ratings of such sprinklers should be appropriate to their locations and the operating temperature of the equipment. 

Fire detection and sprinkler systems are beneficial but if used with high bay racking consideration should be given to incorporating inter-rack sprinklers which counteract the chimney effect of a fire. Care should be taken that no water-reactive chemicals are stored below sprinkler installations. The advice of the local fire prevention officers, sprinkler suppliers. 

Where subject to temperatures below 40°F (5°C), a wet-pipe system cannot be used.There are two recognized methods of maintaining automatic sprinkler protection in such locations (1) through the use of systems where water enters the sprinkler piping only after operation of a control valve... 

The protection area per sprinkler tor hydraulically designed systems with densities below 0.25 gal/min fF may exceed 100 fF.but shall... 

OSHA also requires at 1910.159(c)(10) regarding sprinkler clearance that when stacking items, The minimum vertical clearance between sprinklers and material below shall be 18 inches (45.7 cm). ... 

---