Extinguishants dry powder

A colourless gas, b.p. — 59-C/740 mm. Used as a relatively non-toxic propellant gas in fire fighting apparatus, e.g. dry-powder extinguishers. Made by the bromination of fluoro-form, CHF3. 

Potassium bicarbonate is used in foods and medicine. It is approximately twice as effective as NaHC03 in dry-powder fire extinguishers, perhaps because the potassium affects the free-radical mechanism of flame propagation. However, the material does not have good handling characteristics. 

The metal reacts violently with water, ice, steam, lower molecular weight alcohols, and chloriaated hydrocarbons. In the presence of air/moisture mbidium can act as an ignition source if a flammable organic Hquid or vapor is also present. Rubidium can ignite spontaneously ia the presence of oxygen and tarnishes rapidly when exposed to air. Burning mbidium should only be extinguished with dry powders, such as dolomite or sodium carbonate. 

Removal of one of the eorners of the fire triangle normally results in extinguishment of a fire. Propagation of a flame ean also be stopped by inhibition of the ehain reaetions, e.g. using dry powders or organo-halogen vaporizing liquids. 

The penetration and eooling aetion of water is required with Class A fires, e.g. those involving paper, wood, textiles, refuse. Water is applied in the form of a jet or spray foam or multi-purpose powder extinguishers are alternatives. Extinguishment of a Class B fire ean be aehieved by the smothering aetion of dry ehemieal, earbon dioxide or foam. Most flammable liquids will float on water (refer to Table 6.1 under Speeifie gravity ), so that water as a jet is unsuitable a mist may, however, be effeetive. Water is also widely used to proteet equipment exposed to heat. Dry powders are effeetive on flammable liquid or eleetrieal fires. 

Dry powders are effeetive on flammable liquid or eleetrieal fires. Speeial powders are available for use on metals. Dry powder extinguishers may be used on Class C fires, ineluding gases and liquefied gases in the form of a liquid spillage or a liquid or gas leak. This must be aeeompanied by other aetions, e.g. stopping the leak this is neeessary to avoid aeeumulation of an unburned flammable gas-air mixture whieh eould subsequently result in an explosion. Aetivation may be automatie by a deteetion system, or manual. 

Extinguisher type Water Carbon dioxide Dry powder Foam Vaporizing liquicf Fire blanket Sand... 

Leave space for possible hose runs for a fire in any stack and provide dry powder extinguishers around the area. 

Fire Hazards - Flash Point Not flammable but may cause fires upon contact with combustible materials Flammable Limits in Air (%) Not pertinent Fire Extinguishing Agents Flood with water, dry powder (e.g., graphite or powdered limestone) Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Not pertinent Behavior in Fire Can increase the intensity of fires Ignition Temperature Not pertinent Electrical Hazard Not pertinent Burning Rate Not pertinent. 

Impact damage occurred to one of 48 10 kg polypropylene tubs of calcium hypochlorite, each closed with a polythene lid, all supported on a wooden pallet and stretch-wrapped round the base with polyethylene film. The spilled material was swept up and discarded, and the pallet was moved to another part of the warehouse, and some 30 mins, later flames were seen at the base of the pallet [1]. Ignition was attributed to contact between residual solid hypochlorite on the pallet and lubricant drips on the concrete floor from fork lift traffic. Application of a dry powder extinguisher had little effect on the fire, but use of a 40 1 water extinguisher led to rapid escalation of the fire as contact between hypochlorite... 

Surface contamination of 2 kg of the dry salt with as little as 2 flakes of moist potassium hydroxide caused a vigorous self-sustaining fire, which was extinguished with water, but not by carbon dioxide or dry powder extinguishers. 

Fires involving alkylaluminium compounds are difficult to control and must be treated appropriately to particular circumstances [1,5,6], usually with dry-powder extinguishers. Halocarbon fire extinguishants (carbon tetrachloride, chloro-bromomethane, etc.), water or water-based foam must not be applied to alkylaluminium fires. Carbon dioxide is ineffective unless dilute solutions are involved [5,6], Suitable handling and disposal procedures have been detailed for both laboratory [1,2,5,6,7] and manufacturing [5,6] scales of operation. 

Dry powder fire extinguishers containing bicarbonate should not be used on nitromethane or nitroethane. 

---