What is the difference between water and water mist extinguishers?

[Guest mohammFaroo]

I am confused. Water extinguishers can't be used near electricity, water mist can!?!?!?

Water extinguishers can't be used on fat, water mist can?!?!?

Why is water mist five times more expensive than a water extinguisher??

[Safelincs]

The fog created by the water mist is unable to conduct electricity (at typical business voltage anyway), as there is a distance between each microscopic droplet. In addition the mist does not form puddles that could conduct electricity. The best water mist fire extinguishers also use electrically non-conducting de-ionised water.

Normal water droplets sink into hot fat and then erupt violently as they turn into steam, while water mist turns into steam ABOVE the hot fat, cooling the surface and dispelling oxygen from the surface. It should be noticed, though, that water mist should only be deployed on small fat fires.

The price of the models mentioned is mainly based on the special nozzle and dip tube, which contains a rotating 'dispenser', which intersperses water particles with nitrogen gas.

Harry

[Tom Sutton]

Water and foam extinguisher's that has passed the dielectric test should not be use directly on live electrical equipment without consultation with the manufacturer or fire and rescue service. The best solution is the isolate the mains supply and allow any capacitance to discharge then it’s safe to use water.

DO NOT USE WATER ON COOKING OIL OR FAT FIRES only use extinguishers that have passed the class F test and have a rating higher enough to deal with the size of fire you are dealing with.

[Safelincs]

Hi Tom

I agree, normal water extinguishers should never be used on fat fires. However, the dry water mist extinguishers were designed as a solution for small fat fires and are F rated and certified. Watch the application of this

including a F-class fire.

The Dry water mist extinguishers also have passed the dielectrical test up to 35000 V, so can be used safely near electrical appliances of up to 1000 Volt at a 1m safety distance. 

Harry

[Guest Guest D]

Hi, Some websites say water mist extinguishers can be used on all classes of fire but some are saying they can't be used on class D fires. Is anyone able to confirm which is correct? Many thanks

[Safelincs]

Hi,

Water mist fire extinguishers (manufactured using de-ionised water) can be used on most types of fires in an office, home, public settings. That includes A,B,C, F class fires as well as electrical risks up to 1000V (at one meter). So, the perfect office and home extinguisher.

Class D fires on the other hand (basically burning metal swarf, such as magnesium from machining operations) are a risk usually restricted to machining workshops and the water mist would be unsuitable, as water increases the chemical reaction of Class D fires.

Harry

 

[AnthonyB]

Whilst water mist doesn't scatter the burning metal like water jet or water spray the flaming will intensify as the water reacts with the metal until eventually it cools such that it stops burning. This doesn't look to problematic on the demo videos with a tiny amount of magnesium swarf in the middle of a yard but in real world situations may have effects you would not want - it's better to have a proper Class D powder.