QUOTE(ozak @ Nov 17 2015, 03:58 PM)
Not so easy.
DISADVANTAGES
X Visibility Problems - The application of dry powder and generation of a dense powder cloud will dramatically reduce the visibility of the operator so they may not be able to use vision to judge the effectiveness of the powder on the fire or may jeopardise escape in a fire.
X Can Cause Breathing Problems - If dry powder is inhaled it can irritate the respiratory organs. Whilst short term exposure is not considered to be harmful, repeated inhalation should be avoided.
X Leaves a Residue - Dry powder is a very messy extinguishing agent that will leave behind a residue that is corrosive to certain materials and because it is a find powder it can also be abrasive. Thoughtless use may lead to the powder causing more damage than the fire itself, using dry powder fire extinguishers in kitchens or offices as powder can contaminate food and inhibit the use of electrical components such as keyboards if discharged. Because of the properties of powder being very light and easily carried through the atmosphere dry powder extinguishers when discharged risk contamination over a wide area.
X Poor Post Fire Security - Due to the smothering and chemical interference effect of dry powder, it will only remain effective whilst it is present in the atmosphere above the fuel. Because it is a cloud of fine powder, particles of it can easily be dispersed by the wind, giving a very real danger of rapid re-ignition of fuel.
X Vulnerable To Packing Down – Failure of extinguisher can result from the packing down of the powder within the extinguisher body, this problem is associated more with cartridge operated extinguishers. This can be a particular problem on vehicle mounted equipment as the vehicle vibration will cause the powder to compress under its own weight. Regular maintenance routines are essential; to prevent failure of equipment at a crucial time.
X Can Break Down Foam Blanket – The use of dry powder close to an area covered by a foam blanket may lead to the foam breaking down more quickly.
X Usage & Location – Because of the disadvantages above dry powder extinguishers should only be found in industrial settings and where no alternative fire extinguisher mediums are suitable. They should not be found in offices, flats etc.
X Limit of use, not to be used on class D,F fires