About dry powder fire extinguisher
Dry powder fire extinguisher uses carbon dioxide gas or nitrogen gas as power to spray dry powder fire extinguishing agent to extinguish the fire. Dry powder fire extinguishing agent is a kind of dry and easy flowing fine solid powder, which is composed of base material, moisture-proof agent, flow promoter, agglomeration inhibitor and other additives, mainly including ammonium phosphate, sodium bicarbonate, sodium chloride, potassium chloride dry powder fire extinguishing agent, etc. It can be used to put out the incipient fire of oil, organic solvent, flammable liquid, flammable gas and electrical equipment. The dry powder fire extinguisher can be divided into three types: portable type, backpack type and cart type.
Fire fighting principle
The dry powder fire extinguisher is filled with ammonium phosphate dry powder fire extinguishing agent. Dry powder fire extinguishing agent is a dry and easy flowing fine powder used for fire extinguishing. It is composed of inorganic salt with fire extinguishing efficiency and a small amount of additives, which are dried, crushed and mixed into fine solid powder.
In addition to the special dry powder chemical fire extinguishing agent for metal fire, the dry powder fire extinguishing agent is generally divided into BC dry powder (sodium bicarbonate) and ABC dry powder (ammonium phosphate).
First, the volatile decomposition products of inorganic salts in the dry powder have chemical inhibition and negative catalytic action with the free radicals or active groups produced by the fuel in the combustion process, so that the chain reaction of combustion is interrupted and the fire is put out;
Second, the powder of dry powder falls on the surface of combustible materials, chemical reaction occurs, and forms a glass like covering layer under the action of high temperature, so as to isolate oxygen, and then suffocate and extinguish the fire. In addition, it has the function of partial dilution of oxygen and cooling.
Classification of dry powder fire extinguisher
Dry powder fire extinguisher can be divided into ABC type and BC type.
That is, portable dry powder fire extinguisher and cart type dry powder fire extinguisher, backpack type dry powder fire extinguisher.
Storage requirements of dry powder fire extinguisher
1、 The storage device of dry powder fire extinguishing system should be composed of dry powder storage container, container valve, safety pressure relief device, driving gas storage bottle, bottle head valve, collecting pipe, pressure reducing valve, pressure alarm and control device, etc. And shall meet the following requirements:
1. The dry powder storage container shall comply with the current national standard "Supervision Regulation on safety technology of pressure vessels"; the driving gas storage bottle and its filling coefficient shall comply with the current national standard "Supervision Regulation on safety technology of gas cylinders".
2. The design pressure of dry powder storage container can be 1.6Mpa or 2.5MPa, the loading coefficient of dry powder fire extinguishing agent should not be greater than 0.85, and the pressurization time should not be greater than 30s.
3. The operating pressure and rated discharge capacity of the safety relief device shall be in accordance with the current national standard general technical conditions for components of dry powder fire extinguishing system (gb16668).
4. The dry powder storage container shall meet the requirements of driving gas coefficient, dry powder storage capacity, dry powder conveying rate and pressure at the outlet of output container valve.
2、 Inert gas should be selected as driving gas, nitrogen should be selected; water content of carbon dioxide should not be greater than 0.015% (M / M), other gases should not be greater than 0.006% (M / M); driving pressure should not be greater than the maximum working pressure of dry powder storage container, otherwise it is easy to cause safety accidents.
3、 The storage device of dry powder fire extinguishing system shall be arranged to facilitate inspection and maintenance and avoid direct sunlight. The ambient temperature should be ― 20 ℃～ 50 ℃.
4、 The storage device of dry powder fire extinguishing system should be set in the special storage device room. The setting of special storage device room shall meet the following requirements:
1. It should be close to the protection area, and the exit should directly lead to the outdoor or evacuation passage.
2. The fire resistance rating shall not be lower than grade II.
3. It should be kept dry and well ventilated, and emergency lighting should be provided.
5、 When the measures of moisture prevention, antifreeze and fire prevention are taken, the storage device of local fire extinguishing system can be set in a fixed safety fence.
Scope of application
It is mainly used to put out the initial fire of oil, organic solvent and other flammable liquid, flammable gas and electrical equipment. It is suitable for fighting all kinds of flammable and combustible liquid and gas fires, as well as electrical equipment fires.
