Compare Mist with Sprinklers
Domestic & Residential Mist Systems
The following information is aimed at the residential sprinkler industry.
The publication of a British standard for water mist fire systems produced by the British Research Establishment (BRE) has been welcomed by the fire sprinkler industry because it has finally produced specific test criteria which water mist suppression systems and components can be measured against. The reason for this delay is partly due to the fact that water mist systems have traditionally been very ‘project specific’ which has made it difficult to produce a broad set of guidelines for their use.
Conventional fire sprinkler systems have been in use for over 100 years whereas mist systems have only been developed comparatively recently and, unlike conventional fire sprinkler systems they do not have the same proof of performance or legacy of 100 years of test data in an extensive range of fire hazards to refer to.
The comparatively short history of Water Mist Fire Suppression Systems
Water mist fire suppression systems were originally developed as an alternative to Halon based fire suppression systems for storage areas and machinery enclosures in ships and various commercial applications.
Such systems performed very well in specific situations where there were no design variables like opening windows or varying fire loadings and where doors would generally be kept closed etc. These systems have subsequently been utilised in land based commercial situations like engine rooms, local asset management of electronic equipment, commercial kitchens, turbine systems etc.
More recently, water mist fire suppression systems have been considered in residential situations and a number of low pressure residential and domestic mist systems have been installed throughout the UK. However, it is fair to say that far more conventional fire sprinkler systems have been installed in the same period using components which have been subjected to extremely rigorous testing procedures over many years in a multitude of different design scenarios.
What is the difference between a Water Mist fire system and a conventional fire sprinkler system?
It has been known for a long time that water droplets evaporate when applied to a fire and the resulting steam reduces the concentration of oxygen close to the fire which in turn interrupts the chain reaction necessary for a fire to establish itself. This is the process for any sprinkler system.
However, Water Mist suppression systems improve on this basic process by producing a finer spray (or mist) than a standard fire sprinkler nozzle. A fine mist is a very effective way of ensuring that water evaporates quicker thus slowing down the combustion process even more effectively than a conventional fire sprinkler system. In order to achieve a finer spray, mist systems operate at a higher pressure than standard conventional sprinkler systems and in most situations can be as effective if not more effective than a conventional residential fire sprinkler system despite the reduced quantity of water used. They are broadly classified as low and high pressure.
What is the difference between a low pressure and high-pressure mist system?
Although low pressure mist systems have been utilised for some time in residential applications, a more recent development in the industry has been a high-pressure mist system manufactured by Plumis. This innovative system operates at around 8-12 times the pressure of a low-pressure mist system and uses considerably less water. Although a low-pressure mist system could never be connected to a town main due to the pressure requirement, a high pressure Plumis system is designed to directly pump water from a standard domestic water connection without exceeding the maximum quantity of water permitted by Water Regulations.
This fundamental difference has proved incredibly useful in situations where sprinkler coverage has been required in domestic situations where it hasn’t been possible to replace the existing water mains supply or where it would prove too expensive to provide an up-graded water supply to a new build project.
Call 01892 680090 and talk to an engineer for more information.