Dry Chemical is a powder composed of very small particles usually of sodium
bicarbonate, potassium bicarbonate, urea-based potassium bicarbonate, or monoammonium phosphate with added particulate material supplemented by special treatment to provide resistance to packing, resistance to moisture absorption (caking) and the proper flow capabilities
[FIRE EXTINGUISHING MECHANISMS]
・Interruption of the chain reaction sequence.
・Heat absorption effects
Multipurpose Dry Chemical is usually monoammonium phosphate-based and is effective on fires in ordinary combustibles, such as wood or paper, as well as on fires in flammable liquids, etc
1. Best applicable to fire extinguishing systems for protection of dangerous and associate articles which involve serious hazard and the danger of quick spread of fire.
2. Easy to clean arter application of Dry chemicals Economical as they are less contaminative.
3. Excellent insulation permits application of Dry chemicals to high-tension electric installation such as a transformer.
4. Handling of Control Valve is simple and plain ensuring easy cleaning of piping after use
TOTAL FLOODING SYSTEM
A total flooding system means a supply of dry chemical permanently connected to fixed piping,wiht fixed nozzles arranged to discharge dry chemical into an enclosed space or enclosure about the hazard.
This type of system shall be used only where there is a permanent enclosure about the hazard that is adequate to enable the required concentration to be built up.
The leakage of dry chemical from the protected space shall be minimized since the effectiveness of the flooding system depends upon obtaining an extinguishing concentration of dry chemical.
In total flooding system, the rate of application shall be such that the design concentration in all parts of the enclosure shall be obtained within 30 seconds.
LOCAL APPLICATION SYSTEM
Local application system shall be used for the extinguishment of fires in flammable or combustible liquids, gases, and shallow solids such as paint deposits, where the hazard is not enclosed or where the enclosure does not conform to the requirements for total flooding. Application of dry chemical shall be from nozzles mounted on the tank side or overhead.
Applicable to superficial fire, and the amount of extinguishing agent depends upon the hazardous area.
Applicable to cubical fire, and the amount of extinguishing agent depends upon the volume of the object in danger.The hazard shall include all areas that are or may become coated by combustible or flammable liquids or shallow solid coatings, such as areas subject to spillage, leakage, dripping, splashing, or condensation, and all associated materials or equipment such as freshly coated stock, drainboards, hoods, ducts, etc., that might extend fire outside or lead fire into the protected area.System DiagramDRY CHEMICAL AGENT1.Sodium Bicarbonate Based Dry Chemical.
This agent consists primarily of sodium bicarbonate(NaHCO3) and is suitable for use on all types of flammable liquid and gas fires (Class B) and also for fires involving
energized electrical equipment (Class C).
Sodium bicarbonate base dry chemical is not generally recommended for the extinguishment of fires in ordinary combustibles (Class A), although it may have a transitory effect in extinguishing surface flaming of such materials.
2NaHCO3 —> Na2CO3+CO2+H2O
Na2CO3 —> Na2O+CO22.Potassium Bicarbonate Based Dry Chemical.
This agent consists primarily of potassium bicarbonate(KHCO3) and is suitable for use on all types of flammable liquid and gas fires (Class B) and also for fires involving energized electrical equipment (Class C).
Dry chemicals based on the salts of potassium are not
generally recommended for the extinguishment of fires in ordinary combustible (Class A), although they may have a transitory effect in extinguishing surface flaming of such materials.
2KHCO3 —> K2CO3+CO2+H2O
K2CO3 —> K2O+CO2