Fine water mist
One potential halon replacement undergoing extensive development is the use of fine water mist – a water droplet size distribution where 99 per cent of the water volume is contained in droplets less than 1 mm in diameter. The most effective fine water mist systems have a volumetric average droplet size diameter of about 40 µm. ADA Technologies, the United States, has been a leader in fine water mist research since 1993. The applications addressed in ADA’s current research and development programme include protection against fires in aircraft and fires in microgravity environments aboard spacecraft.


A proof-of-concept system for the aircraft fire application features a total weight of less than 34 kg, with over 18 kg of water available for application to the target fire. The layout is simple, robust and modular for ease of installation and maintenance. This module, designated the Modular Effervescent Atomization System (MEAS), is intended to protect about 1,000 ft3 volume. ADA’s effervescent atomizer consists of a radial expansion nozzle, designed to create a supersonic flow section. The supersonic flow creates a shock wave that returns the flow to atmospheric pressure. In passing through the shock, the water droplets are further broken up to generate a fine water mist discharge to the protected space.


ADA’s MEAS has certain advantages over conventional fine water mist fire suppression systems. Relative to a single-fluid system:
 
  • There is no need for a high-pressure pump, which requires auxiliary power supplies and may fail; and
     
  • The atomizer orifices can be larger so clogging does not occur.
    Relative to a dual-fluid system:
     
  • The integrated agent supply/nozzle assembly eliminates the need for large propellant gas supply lines; and
     
  • The secondary effervescent atomization generates smaller droplet sizes with less propellant gas.
     

Contact: Mr. Jim Butz, Vice President, ADA Technologies Inc., 8100 Shaffer Parkway, Suite #130, Littleton, Colorado 80127-4107, United States of America. Tel: +1 (303) 792 5615; Fax: +1 (303) 792 5633


E-mail: Jimb@adatech.com


Source: www.adatech.com

Solid-solid hybrid gas generator compositions for fire suppression
Mainstream Engineering Corporation, the United States, has secured a patent on a solid-solid hybrid gas generator composition, which includes a solid gas generator material and a solid flame retardant material. The flame retardant material may include one or more bromine-, chlorine- and phosphorous-containing compounds. The system is designed as a halon replacement technology.


The flame retardant material in the hybrid gas generator has several functions. First, its decomposition generates radical-scavenging decomposition products, which serve as chemically acting fire suppression agents. Since chemically acting agents are delivered to the fire, significantly less inert gas needs to be delivered. Thus, the hybrid system is significantly smaller and lighter than the current gas generator fire suppression systems. Second, it serves as a heat sink for the exothermic gas generation reaction, resulting in delivery of a cool gas to the fire. Third, when formulated directly with the inert gas generator, it acts as a binder for the formulation. This feature makes the formulation abrasion resistant.


The solid-solid hybrid gas generator has another advantage over conventional inert gas generator systems and the hybrid systems that use liquid or vapour agents. It requires only one storage vessel for both halogen-containing flame retardants and the gas generator materials. The solid flame retardant material has acceptable atmospheric properties and does not pose any global warming or ozone depletion threat during manufacturing, storage and handling. Upon release, the solid materials are in a very reactive form and are removed readily by the fire or in the troposphere, unlike gas and liquid agents that may not fully react when used, thus posing a threat to the environment.


Source: www.freepatentsonline.com
Fire suppression system
Kidde IP Holdings Limited, the United Kingdom, has received a United States patent on a system for discharging inert gas for extinguishing or suppressing a fire. The system has a fluid discharge control arrangement, which reduces the pressure in the fluid flow path downstream, thereby allowing the downstream pipe work to be selected to withstand a lower pressure than in a conventional system.


The fluid discharge control device described in the patent comprises a valve and a restrictor in the first flow path, and another valve-restrictor combination in the second flow path. Fluid (inert gas) from the containers flows initially through a first flow path and then through a second flow path, with the valves regulating the flow and the restrictors reducing the peak pressure. The system is designed to function with inert gases used as replacements for halon suppressants.


Source: www.freepatentsonline.com
Fluorine-free fire fighting agents
Chemguard Inc., the United States, has patented a foam concentrate that provides a fire-fighting composition when mixed with water. The concentrate is formed from the added water, and a high molecular weight acidic polymer (HMWAP) and a co-ordinating salt in the concentrate. The fire fighting concentrate is a synthetic type that meets and exceeds UL162 requirements for use on Class B fires.


The invention provides a method of extinguishing Class B non-polar liquid fires using the fire fighting compositions, either without or with very low added fluorochemical surfactants or fluorinated polymers. This method provides fast extinguishment and burn-back similar to that provided by FP and AFFF agents having high fluorochemical surfactant content. The HMWAPs used in the concentrate may include those containing multiple carboxylic acid groups or other functionally acidic groups, like sulphonic and phosphoric groups. The coordinating salts prefrerred are those having oxidation states of +2 and +3, such as the salts of aluminium, boron, calcium, iron, magnesium and zinc, but could also be barium, antimony, copper, etc.


Source: www.freepatentsonline.com