The technical requirements of foam fire extinguishing system mainly include the following aspects:
System composition and classification: Foam fire extinguishing system is generally composed of foam liquid storage tank, foam fire pump, foam proportioning mixer (device), foam generating device, fire detection and start control device, control valve and pipeline and other system components. The system can be divided into liquid spraying system, liquid spraying system and semi-liquid spraying system according to the spraying method; according to the system structure, it can be divided into fixed system and semi-fixed system.
Selection of foam liquid: The selection of foam liquid should be adapted to the type of fire extinguishing system, the nature of the combustibles to be extinguished, the water quality of the water supply, etc. For example, when extinguishing a fire of a non-water-soluble flammable liquid storage tank, fluoroprotein or water-forming foam liquid should be used; when extinguishing a fire of a water-soluble flammable liquid that is destructive to ordinary foam, anti-soluble water-forming, anti-soluble fluoroprotein or low-viscosity anti-soluble fluoroprotein foam liquid should be used.
Foam fire water pump and foam liquid pump: Foam fire water pumps should be selected with a flat characteristic curve, and their working pressure and flow rate should meet the system design requirements. The working pressure and flow rate of the foam liquid pump should also meet the system design requirements, and at the same time, it should be ensured that the foam liquid supply pressure is greater than the water supply pressure within the design flow range.
Foam proportion mixer (device): Foam proportion mixer is a device that mixes water and foam stock liquid in a specified proportion. Common types include balanced proportion mixing devices, mechanical pump-in proportion mixing devices, and bladder pressure proportion mixing devices. Fixed systems should use balanced, mechanical pump-in, bladder pressure proportion mixing devices or pump direct injection proportion mixing processes.
Scope and restrictions: Foam fire extinguishing systems are applicable to the design, construction, acceptance and maintenance management of new, rebuilt and expanded projects, but are not applicable to ships, offshore oil platforms and other places. In addition, foam fire extinguishing systems should not be used in places containing chemical substances and strong oxidants such as nitrocellulose and explosives that can oxidize rapidly in an airless environment, as well as low-boiling point flammable liquid storage tanks with a boiling point below 45°C.