Sprinklers For Life International Conference Glasgow SSEC 2000
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Water mist applications
DATA CENTERS
Choosing a water mist system rather than a clean agent gas system may eliminate the need for special room alterations or HVAC shutdowns. Backup generator rooms are another critical area within the data center infrastructure because these spaces contain hydrocarbon fuel, which can contribute to very intense fires. Water mist systems are especially effective in rapidly extinguishing these high-energy fires.
INDUSTRIAL FRYERS
Industrial oil cookers are a unique fire hazard in the large-scale industrial cooking industry. Using clean, potable water combined with a fine water mist discharge, it penetrates the fire, blocks radiant heat, and cools the oil below its auto-ignition temperature. High-pressure water mist systems are usually configured to provide protection for fryer hood, fines box, takeout conveyor, and the vertical exhaust ducts.
HISTORICAL/CULTURAL HERITAGE BUILDINGS
In the event of a fire, the high-pressure fine water mist rapidly cools and suppresses the fire using minimal amounts of water to preserve artifacts and decorations. Water mist systems also offer installation advantages, because their small, bendable stainless-steel tubes are easy to install, are low-profile and can preserve building aesthetics because they can be tucked behind a variety of design elements, such as crown molding.
POWER PLANTS AND HEAVY INDUSTRY
The worst-case scenario is when the leakage breaks out close to the hot surfaces of the equipment and a fire results. High-pressure water mist fire suppression systems can protect machinery from fire at the source, keeping damage and downtime to a minimum.
LOWER TOTAL COST OF OWNERSHIP
Although a water mist system may require a larger upfront investment than a conventional sprinkler system, the total cost of ownership may be lower, taking into account the superior durability and lower maintenance costs associated with some manufacturers' water mist systems.
Water mist fire suppression design approaches
Water mist systems can also be designed to provide various suppression approaches, as described below.
PRE-ACTION
These are designed to activate in the double interlock dry-pipe pre-action style; meaning that two different actions must occur to discharge the water. With smoke detectors or heat sensors operating the valves in both systems, the water is held back from flowing until the frangible temperature bulb on a particular discharge head is activated by the heat from a fire. Only then is the water allowed to flow through the system piping/tubing to the activated sprinkler head.
TOTAL FLOODING
A total flooding water mist system is a dry pipe system designed to discharge mist uniformly throughout the entire enclosure/compartment through open discharge heads, making water mist more cost-effective than other agents, because there is no need to tightly seal the protected space.
LOCAL APPLICATION
Water mist fire suppression systems can be designed to protect specific equipment within a larger enclosure. During the design and installation, the discharge heads must be carefully selected and positioned, within the guidelines of the systems' design manual to provide the required coverage, flow and distribution patterns.
FACILITY-WIDE PROTECTION
This means that a water mist system can be the primary fire suppression system for both hazardous and non-hazardous and spaces, eliminating the need for traditional sprinklers in areas where water mist is deployed. The bottom line is, water mist fire suppress systems are a viable and cost-effective solution.
When a fire is detected, the system discharges a fine water mist. This mist absorbs heat and displaces oxygen at the core of the fire and blocks radiant heat to control, suppress or extinguish fires.
Water mist also helps pre-wet and block heat transfer to adjacent combustibles which decreases the risk that the fire will grow and spread. When dealing with occupied spaces, having a suppression system that dissipates heat and reduces smoke also allows for a safer evacuation and assists in maintaining the structural integrity of the area it is protecting.
The effectiveness of water mist suppression is due to the size of the water droplets emitted by its discharge heads. To offer an idea of droplet size, sprinkler systems have a droplet size over 1000 microns, low-pressure systems droplets are sized at just under a thousand micron-the thickness of a dime-while intermediate pressure produces 300 to 500-micron droplets. High-pressure systems, which are the most widely used water mist systems today, produce 50 to 100-micron size droplets. These significantly smaller droplets provide a larger surface area for heat transfer/absorption, which causes much of the water mist to be vaporized into steam.
Since much of the water is vaporized during the suppression process, water damage to property and critical assets is minimized. Less water also means faster cleanup and minimal business interruption-because spaces can become reoccupied and operational in a shorter time following a fire.
Another benefit of water mist is its smoke-scrubbing capabilities. Smoke is not a gas, but a cloud of very small particles. Because particles stick to the surface of water droplets, water mist has the effect of cleaning the air. This is welcome as the particles involved can be highly toxic or carcinogenic, and smoke Inhalation is a major cause of death in fires.
Manufacturers & traders should be insisting on this as minimum level protections. Insurers, you're being taken for fools.
25 yrs after #Scottsdale Arizona's #FireChief explained his department's long fight to persuade investors misting saves lives with minimised after fire impacts clean up.