Firefighting units and foam concentrates

Fire extinguishing units with foam of low, medium and high expansion are used at different industrial facilities, oil refineries, production shops, warehouses of various industries among them. Requirements for the design of automatic fire extinguishing systems are established by GOST 12.3.046 and GOST R 50800. Foam concentrates and wetting agents are used in sprinkler and deluge systems. The choice depends on the fire hazard of the facility. In the article we tells you how to choose the extinguishing agent in order to get an effective and economically viable firefighting system.

Content:

• Sprinkler and deluge fire extinguishing installations
• Composition of foam fire extinguishing installations
• Types of extinguishing agents for a firefighting installations
• Pozhneftehim foam concentrates for firefighting
• Fire extinguishing systems with wetting agent
• Advanced training courses: foam extinguishing

Pozhneftehim manufactures dosing (proportioning) systems, bladder tanks, foam concentrates and equipment for foam sprinkler and deluge type fire extinguishing systems. We offer customers standard design solutions and integrated supplies of fire extinguishing systems. The use of foam systems and fire extinguishing units with a wetting agent in accordance with the requirements of SP 5.13130 allows to save on flows and water reserves for the facility. The purchase costs of pumping units, water tanks, energy consumption, and area required for pumping units are therefore reduced.

Sprinkler and deluge extinguishing systems

Sprinkler system – fire extinguishing unit, which is triggered when a specified level of air temperature is reached. When the temperature rises, the thermal lock of the sprinkler irrigator opens and extinguishing agent is supplied from the pipeline, which is constantly under pressure. The extinguishing agent may be water or water with a foam concentrate (wetting agent).

Deluge system – fire extinguishing unit, which is triggered when a signal is received from a fire detection system. The deluge system can be started manually or when a signal is sent from the fire alarm system. The extinguishing agent may be air-mechanical foam, water, water with a foam concentrate (wetting agent).

Drencher sprinklers vary in design, but must comply with the requirements of the state standard GOST R 51043-2002. The use of standard deluge irrigators at a number of facilities may not be effective due to the design and technological features of warehouses, production shops and other buildings and premises. In these cases, Pozhneftehim recommends choosing the universal Antifire water-foam nozzle, which is a special deluge sprinkler in compliance with GOST R 51043-2002 “Automatic water and foam fire extinguishing units. Sprinklers." Thisdeluge sprinkler is designed to supply low expansion foam and water in a wide pressure range. The Antifire water-foam nozzle can be equipped with an oscillator for a larger irrigation area.

There are 2 popular errors in designing foam fire extinguishing units.

1. Using solution-filled pipelines. Given the current environmental requirements, there are no foam concentrates that can retain fire-fighting capacity when stored in solution. Therefore, at the initial moment of starting the fire extinguishing installation, aqueous solution will be supplied instead of extinguishing foam, which in case of highly flammable and combustible liquids will cause a fire to spread .
2. Using S type foam concentrate according to GOST R 50800 with standard water sprinklers. Type S foam concentrate is designed for extinguishing with medium expansion foam. If is not effective when used with low-expansion water-foam nozzlesfor fire extinguishing of highly flammable and combustible liquids.

Composition of foam fire extinguishing installations

A fire extinguishing agent is one of the main elements of a fire extinguishing installation, along with a dosing system, foam generators, and a pumping station.

Pozhneftehim, a Russian manufacturer of firefighting equipment and foam concentrates, offers comprehensive fire extinguishing systems for facilities of various industries. We cooperate with design organizations throughout Russia, and also, upon request, develop concepts of anti-fire defense, , coordinate Special technical conditions and provide standard design solutions to our customers.

According to A.3 table of SP 5.13130.2009, the type of automatic fire extinguishing unit, the method of extinguishing, and the type of fire extinguishing agent are determined by the design organization. The design organization selects the extinguishing agent taking into account the recommendations of the Reference book A.Ya. Korolchenko, D.A. Korolchenko “Fire and explosion hazard of substances and materials, and means of firefighting” (hereinafter referred to as Korolchenko’s Reference book) and section 5 of the recommendations of FGBU VNIIPO of EMERCOM of Russia “Firefighting equipment. Scope. Type selection” (hereinafter Recommendations of FGBU VNIIPO of EMERCOM of Russia). For example,

Cotton

Fire hazard: Flammable, combustible, fibrous material. Can smolder for a long time from the ignition source (spark, smoldering cigarette, etc.). Ignition temperature 210 °C:. Self-igniting temperature 407 °C: cotton dust can form explosive dusty air mixtures with concentration 50 g/m3: max. explosion pressure 630 kPa: rate of pressure rise: average 12.9 MPa/s. Max. 17.5 MPa/s: min ignition energy 25 mJ: Minimum explosive oxygen content 17% vol. Cotton is prone to spontaneous combustion under the action of nitric and sulfuric acids, as well as in contact with oxidizing agents. Vegetable oils that get on cotton are easily oxidized, causing it to spontaneously ignite. Selfheating temperature of raw cotton 60 °C; Smolding temperature 205 °С: conditions of thermal spontaneous combustion: lg tc = 2.018 + 0.140 lg S:1g tc = 2.332 - 0.05gt.

Extinguishing media: Sprayed water with wetting agents, air-mechanical foam. Water extinction is ineffective.

Information on the fire hazard of the material. Example from the Korolchenko reference book

Types of extinguishing agents for a fire extinguishing installation

Foam fire extinguishing units are subdivided according to the foam expansion into low, medium and high expansion systems. Low and medium expansions are used to extinguish a fire over an area. High expansion foam is necessary for the volume method of fire extinguishing. The generally accepted classification of foam concentrates of 10 types is proposed in GOST R 50588-2012:

• Aqueous Film-Forming Foam Concentrates AFFF
• Film-forming fluoroprotein foam concentrates FFFP
• Fluoroprotein foam concentrates FP
• Alcohol Resistant Aqueous Film-Forming Foam Concentrates AFFF/AR
• Alcohol Resistant Aqueous Film-Forming Foam Concentrates AFFF/AR-LV
• Alcohol Resistant Film-forming fluoroprotein foam concentrates FFFP/AR
• Alcohol Resistant fluoroprotein foam concentrates FP/AR
• Synthetic alcohol resistant foam concentrates S/AR
• Synthetic foam concentrates S
• Synthetic foam concentrates WA (wetting agents)

Foam concentrates are used to extinguish class A fires (solid substances) and B (combustible liquids). It is economically feasible to use S type foam concentrates and WA wetting agents to extinguish Class A fires.

When choosing a foam concentrate for extinguishing highly flammable and combustible liquids, it is important to know whether the liquid is polar (alcohols, acetone, ethers, aldehydes and ketones) or non-polar (most petroleum products). The main difference is that polar liquids dissolve in water, while non-polar liquids do not dissolve.

Non-polar liquids can be extinguished with foam concentrates of S type (synthetic) and AFFF (Aqueous Film-Forming Foam Concentrates). Polar solvents (water-soluble liquids) suggest extinguishing with alcohol-resistant foam concentrates of the S/AR type (synthetic alcohol-resistant) and AFFF/AR or AFFF/AR LV (fluorosynthetic alcohol-resistant). Extinguishing polar fuels with S and AFFF foam concentrates is not effective. The foam is destroyed by a water-soluble combustible liquid, and fire will cease only as a result of burning out of the combustible substance or dilution.

Some fuels have water-soluble additives (leaded and high-octane gasolines). In such case as well as for warehouses for the joint storage of polar and non-polar liquids, polar foam concentrates must be used.

Flammable and combustible liquids can be extinguished with synthetic and fluorosynthetic foam concentrates. Extinguishing agent is selected depending on the hazard of the facility, environmental and hygiene requirements.

Attention should be paid to the biodegradability of the foam concentrate so as not to include measures for collecting spilled foam concentrate solution.

Pozhneftehim firefighting foam concentrates

Pozhneftehim produces Aquafom foam concentrates at its own production site in the Moscow region. Our product line includes foam concentrates for low expansion only, and foam concentrates suitable for low, medium and high expansion.

The type of foam concentrate is determined not only by the fire load, but by the supply method. The area of application of installations with foam of different expansion ratio and the type of corresponding foam generators are shown in the table.

Fire extinguishing installations with wetting agent

Fire extinguishing installations with a wetting agent have advantages over water extinguishing systems. Water with a wetting agent allows extinguishing fires more efficiently and makes the fire extinguishing unit cheaper by reducing the required flow rate of the extinguishing agent. Accordingly, the capacity of the pumping station, the volume of water in the tanks, the diameters of the pipelines, shut-off and control valves are reduced. The savings are comparable to the costs of the foam concentrate and the dosing system. In this case, the total savings for the entire fire extinguishing installation with a wetting agent, taking into account the mounting services, can be more than 40% of the cost of the water extinguishing unit.

Biodegradability is one of the wetting agent features. Aquafom SM wetting agent is environmentally friendly, does not irritate the skin and mucous membranes; does not cause carcinogenic, mutagenic or sensitizing effects. The quality and safety of Aquafom SM are confirmed by the sanitary-epidemiological report, certificate of state registration and certificate of compliance.

Advanced training courses: foam firefighting

Pozhneftehim invites specialists from design organizations, engineering companies, construction and operating services to the Advanced training courses. The topic: “Modern technologies of foam fire extinguishing at the facilities of the oil, petrochemical and gas industry”. Contact our managers to participate in the courses.

At the Advanced training courses we talk about the features of fire extinguishing systems, fire equipment and foam concentrates that are available on the Russian market, we demonstrate the operation of fire extinguishing systems of low, medium, high expansion with Aquafom foam concentrates produced by our company. The training is conducted by Pozhneftehim LLC under the License of the Ministry of Education of the Tula Oblast No. 0133/03315 dated September 30, 2016.

Conclusions

The fire hazard of the facility, the type of combustible substance and the economic feasibility of applying various design solutions should be taken into account when choosing the extinguishing agent for the firefighting installation.

The foam concentrates of S or AFFF types should be used for water-insoluble liquids. Foam concentrates of S/AR or AFFF/AR should be used for water-soluble liquids, as well as for their mixtures with insoluble.

For textile, powder, fiber, rubber, plastic materials, water extinguishing with a wetting agent or foam is more effective than water. In this case, the unit of water extinguishing with a wetting agent is more economically feasible.

Pozhneftehim specializes in the design and implementation of fire extinguishing systems since 2004. The company produces and supplies firefighting equipment and foam concentrates, dosing (proportioning) systems and auxiliary equipment.

The article was prepared by specialists of Pozhneftehim LLC.

Консультации по тел. +7 (499) 703 01 32, mail@pnx-spb.ru

Ссылка на источник: https://neftegaz.ru/analisis/view/8691-Ustanovki-pozharotusheniya-i-penoobrazovateli