【 Weak current College 】 on air-foam fire extinguishing agent in the application of the depot

Foam extinguishing systems is an important oil depot fire protection systems, fire protection in oil facilities work plays an extremely important role, in line with the air-foam fire extinguishing agent in the depot fire work has been widely applied. Understanding air foam extinguishing mechanism, familiar with the characteristics of air-foam fire extinguishing agent, for better use and management of the oil foam fire extinguishing system, give full play to the foam fire-extinguishing equipment facility feature.

1 air-foam fire theory

Air bubbles by a certain percentage of foam mixed liquid and water, the air agitation, formed through physical interaction with the air bubble film. Foam expansion according to the different nature of foam can be up to 2 ~ 1000 times, relative density (water = 1) in 0.001 ~ 0.5, far less than ordinary combustible liquids, which may give rise to the surface of floating in a liquid, a thick coating of air bubbles.

Air bubble cover from combustion of liquid on the surface of the air, on combustion of liquid surface has good suffocation, cooling effect, coupled with a foam generating steam after heating evaporation, able to dilute the concentration of the combustion zone atmosphere, cut off the flame radiant heat, and thus prevents the combustion of liquid heating evaporation, combustible gas combustion zone, difficult to access for fire fighting capability. It should be pointed out that fire is a complex process, the 4 effects tend to be heavy after another role, you must enclose the whole dynamic point of view to analysis and research. Air bubble more stability, oil closed long face, combined with cooling effect in fighting with good performance to prevent recurrence, the other fire extinguishing agent are incomparable, but also air foam extinguishing agent in oil widely used one of the main reasons.

2 foam extinguishing agent composition and characteristics

Relatively speaking, foam extinguishing systems fire high efficiency, good effect, air-foam fire extinguishing agent is an easy to use, good fluidity, safe and reliable, economical and practical, the depot at present is the ideal medium. By foaming ratio can be divided into low multiples, in multiples, and high-expansion foam fire extinguishing agent 3 types; the foam liquid and water volume mixing ratio, can be divided into 6%, 3%-2 type; as to the raw material composition, can be divided into protein synthesis-2 type and type. Where in the depot in commonly used low expansion foam fire extinguishing agent is protein (protein, animal protein), f-type, water film-3 major categories.

2.1 low expansion foam fire extinguishing agent

GB50074-2002 specifications for the design of the library, aboveground fixed roof, internal floating roof tanks should be set low expansion foam fire extinguishing system, floating roof tanks yishe low expansion foam fire extinguishing system. GB50151-2000 low expansion foam fire-extinguishing system design code stipulates that non-water soluble, b, c liquid storage tanks, when used on injection foam extinguishing liquid, can choose protein, f protein, aqueous film forming foam liquid-liquid; when using liquid injection foam extinguishing, should use fluorine protein, aqueous film forming foam liquid, etc. Low expansion foam fire extinguishing agent may be applied to the fixed, semi-fixed or mobile foam fire extinguishing system, foaming ratio is less than 20, since than the major, foam can distance Jet, wind interference ratio and high expansion foam is strong, the floating roof tanks of liquid, foam sprayed on, easy-to-cover surface protection foam layer, apply to the open fire.

2.1.1 protein foam fire extinguishing agent

Protein foam fire extinguishing agent is made from animal proteins, such as cattle, horses, sheep, pig's hoof Horn, wool or vegetal proteins such as blood in soybean, rapeseed, and in the alkaline (NaOH or calcium hydroxide), through the partially hydrolyzed, join the stabilizer, antifreeze and corrosion inhibitors, preservatives and viscosity control agents, additives and processing concentration. Protein foam liquid raw materials by manufacturers divided into animal protein and protein 2 class. Protein foam fire extinguishing agent is used for oil storage tank fire extinguishing agent, oil tank farm liquid-system on the widespread use of extinguishing agent, domestic products have been serialized and standardization.

Its main advantage is the low price, high resistance to fire, the disadvantage is easy to oxidize corruption, storage time is short.
2.1.2 Fluor protein foam fire extinguishing agent

Oil-hydraulic injection foam extinguishing systems relatively fluid on injection foam fire extinguishing system, a fire extinguishing efficiency, reliability, good clear advantages. Application for a wide range of oil-hydraulic injection foam extinguishing technology, in the early 1980s began to widely apply fluoride protein foam fire extinguishing agent.

Fluor protein foam is in protein foam liquid added to 2% or 1% (volume ratio) of preformed fluorocarbon surface-active agent made of liquid, with the exception of protein foam advantages, but also has good fluidity foam, oil closed role of strong, strong ability of soothing oil, can be applied to the oil tank with liquid injection foam extinguishing systems. At the same combustion, same size, same supply strength, fluoride protein foam liquid ratio protein foam liquid fire extinguishing time by 1/3 ~ 1/2. The disadvantage is that storage time is short, relative protein foam prices higher.

2.1.3 aqueous film forming foam fire extinguishing agent

2000 revised GB50151-2000 low expansion foam fire-extinguishing system design code for the first time in a clear, non-water soluble, b, c liquid storage tanks, when using liquid injection foam extinguishing, should use aqueous film forming foam liquid, etc. Aqueous film forming foam fire extinguishing agent, also known as the "light" foam fire extinguishing agent, is a new type of synthetic foam liquid, mainly by fluorine carbon surface active agent, hydrocarbon surfactants, stabilizers and other additives and water, is the world's recognized performance best oil fire extinguishing agent.

The extinguishing agent is in the early 1980s, the United Kingdom Angus company to protein-based, add appropriate fluorocarbon surface of agent made from film-forming liquid Fluor protein foam, widely used in developed countries. It features high efficiency of fire (fire extinguishing effect of about 4 times the protein foam), good fluidity, antioxidant, anti freeze, can be stored for a long time, you can apply to the oil tank with liquid injection foam extinguishing systems. The disadvantage is that poor and burn resistance foam at high, closed to the oil surface time and stop fighting time is short, in the prevention of recurrence and isolation heat levelPerformance, less protein foam liquid.

2.2 foam liquid

GB50074-2002 specifications for the design of the library, aboveground fixed roof tank, internal floating roof tanks should be set low expansion foam fire extinguishing system, etc., when the floating roof tanks using Center hose configuration of foam mixed fluid manner, can be set in the expansion foam fire extinguishing system. -Made of foam-fluid is a liquid Fluor protein foam, foam foaming ratio between 20-200 can be applied to the local application type, mobile in-expansion foam fire extinguishing system, 50 times less foam liquid storage tanks for liquid on the floor on fire, 50 times more for flowed fire suppression.

According to the low expansion foam fire-extinguishing system design specifications "thematic report compilation (September 1989) and in October 1992 by former Commerce Design Institute in expansion foam fire extinguishing system materials, low expansion foam mixture supply strength for 5 ~ 7L/(min.m2), mixing ratio of 3%-6%, simmering time 60 ~ 120s, fire extinguishing time 3 ~ 5min; in foam mixture supply strength 4 ~ 4.4L (min.m2), mixing ratio of 8 percent, simmering time 60 ~ 90s, fire extinguishing time is 1 ~ 2min. Strength in supply with 4L/(min.m2), multiple protein in the mixture of foam fire extinguishing time 124s; low expansion foam fire extinguishing mixture of proteins is 459s; low level of protein foam extinguishing time is the mixture of 270s.

The above information describes, in expansion foam liquid in the oil surface flow speed, directly in the oil surface, less affected by the oil pollution, fire resistance, and low expansion foam fire extinguishing liquid, high speed, high reliability, saving investment, can be used to fight oil tank fire, can also be used to fight oil depot, soil tank room fire.

The disadvantage is that storage time is short, relative protein foam prices higher.

2.3 high expansion foam fire extinguishing agent

GB50074-2002 "oil library design code amendment, increase soil tank can be set high expansion foam fire extinguishing system. High expansion foam fire suppression as a new type of high efficiency and low-cost technology. High expansion foam fire extinguishing agent in the base material is synthetic surfactant, also known as synthetic foam fire extinguishing agent, as in the preparation of the mixture with water type, divided into fresh water-and seawater-two, foaming multiples of 200 ~ 1000, can be applied to all submerged, local application and mobile fire extinguishing system. Mainly suitable for extinguishing a fire within a limited space, such as oil depot, soil tank room, underground oil pump housing, etc., which can fire extinguishing, and also helps to remove smoke and toxic gas, also applies to the storage area and operation equipment leaks caused by large liquid fire.

High expansion foam than in multiple, low expansion foam, foam with less water consumption quantity big, the submerged speed, fire-fighting capability strong features, in addition to the dosage as foam liquid, so little cost greatly reduce fire. The disadvantage is that high-expansion foam thermal stability, density is relatively small, cannot be used for fire extinguishing oil tank.

3 foam extinguishing agent compatibility issues

Dry powder extinguishing advantages is the ability to quickly control the fire, fire extinguishing speed, its fatal flaw is the cooling effect is very small and easy to produce comes alive after the fire. Advantages of air-foam fire extinguishing agent is thermal stability, resistance to burning ability is strong, thick foam sheathing, cooling effect, with good performance against comes alive. In fighting oil fire, in order to improve the fire effect, often will foam and dry chemical fire extinguishing agent used in conjunction with the first injection rapidly suppress fire extinguishing agent, then spray foam covering oil surface to prevent recurrence, give full play to the strengths of 2 kinds of fire extinguishing agent, can greatly reduce fire extinguishing time. However, because ordinary powder of additives on ordinary foam have a lot of damage, 2 kinds of extinguishing agent encounters, and destruction of a large number of foam to disappear soon after, but reducing the fire effect. Therefore, in the same fire places, at the same time using different fire extinguishing agent, you must first be 2 or more of the extinguishing agent have compatibility. For example, fluorine protein foam extinguishing agent from perfluorocarbon surfactant liquid film provide protection, so that the powder particles and additive molecules between the foam, making the foam from destruction, the powder extinguishing agent will have compatibility.

3.1 powder extinguishing agent and air-foam fire extinguishing agent compatibility

Suitable for extinguishing A, B, C class fire of ammonium phosphate powder extinguishing agent is used with various air-foam fire extinguishing agent compatibility, you can use. Suitable for extinguishing A, B, C class fire of sodium bicarbonate, potassium hydrogen carbonate powder extinguishing agent, ammonium phosphate powder extinguishing agent may with protein, aqueous film forming foam extinguishing agent compatibility, you can use.

Suitable for extinguishing the fire class B, C of sodium bicarbonate, potassium hydrogen carbonate powder extinguishing agent and foam extinguishing agent to be non-compliant and cannot be combined.

3.2 air foam extinguishing agent compatibility between

Fluor protein foam and protein foam extinguishing agent compatibility, you can use.

Aqueous film forming foam extinguishing agent and protein foam fire extinguishing agent, protein foam extinguishing agent to be non-compliant and cannot be combined.

4 air foam extinguishing agent for use and management

4.1 to strict procurement gateway

For new purchases of protein foam fire extinguishing agent, should the State issued production license and product quality analysis report, and in accordance with the standard check every performance meets the technical requirements.

4.2 to ensure the quality of storage containers

Is used to store the foam liquid container should be of steel, stainless steel or HDPE plastic materials processing of special containers, steel storage containers internal application solvent coatings do a wall of anti-corrosion treatment.

4.3 to ensure good storage conditions

Should be stored in a cool, dry place, cannot be placed in outdoor exposure. Storage ambient temperature upper limit is 40 ° c, lower water film and high expansion foam fire extinguishingAgents should be above its freezing point 5 ° c, and other foam liquid as it flows point push 2.5 ℃, usually 0-5 ¡æ, the storage temperature is too high, too low a deteriorating;, it will freeze. Usually the foam liquid storage container should be filled with, and ensure that the seal. Aqueous film forming foam extinguishing agent in the form of the original liquid, can also be stored in a mixture of stocks. Other foam solution only original liquid storage. Different types and different models, or the same model, different manufacturers or production batch of foam extinguishing agent cannot be mixed.

4.4 to periodic inspection

94 under GB15308-the General specifications of foam extinguishing agent "and other regulatory requirements, the main air-foam fire extinguishing agent has made multiple specifications, 25 per cent (50%) of fluid time, fire extinguishing time, 25 per cent (1%) against burn-time, pH value, liquidity, deposit, anti freeze, touch of performance, diffusion coefficients, etc. Should the user request according to the product description should annual sampling inspection. If there is a noticeable deterioration, should stop using; if the modification is not serious, you can continue to use, but to increase the supply of foam mixed ratio or strength.