Water mist portable extinguishers

[DavidCR]

Some portable extinguisher manufacturers sell wartermist portable extinguishers that are rated for A:C fires, good for A fires and safe for electrical C fires.

The C clasification supposedly goes from using non-conducting water (de-ionized or distilled). But the manufacturers does no clarify how safe they are and the NFPA10 does not explain on this.

So my question is if somebody know about this type of extinguisher, or has a reference to read on how safe are this extinguishers for electrical fires, I mean if they are as safe as a CO2 B:C extinguisher to prevent electric shock, are there limits to its security, etc, and if they affect electronic equipment.

 

[cdafd]

more than likely the maker would tell you how close or how much electric they could handle

http://www.koetterfire.com/products/100-020-AX-B270.php

No electrical conductivity back to the operator

http://www.amerex-fire.com/products/product/30

 

[stookeyfpe]

David,

Sorry to be late to the party. Here in Austin the semiconductor industry embraced these portable fire extinguishers. I'll make a couple of telephone calls tomorrow as I am aware of some specific tests that were done given the concerns of using these portable fire extinguishers around ion implanters (for the rest of the audience reading this post - think high voltage and high amperage, well beyond the normal arena of electrical service). I also will say the 240V/150A/60Hz is normal arena electrical service in my current office - its my house.

Give me a couple of days. Your question is valid. I also will be calling Underwriters Laboratories and will plug into their fire extinguisher experts.

 

[stookeyfpe]

DavidCR:

My counterparts in the semiconductor industry came through with some information that may be beneficial. First and most important is that DI water must be used. Using anything else increases the hazard of electric shock because of the minerals found in water.

Second is that the extinguisher must be pressurized with either nitrogen or -40 dew point air. All of the folks I talked to prefer N2 because its inexpensive, its quality can be easily verified, and its generally distributed throughout their buildings for purging and providing pneumatic energy for equipment. Use of conventional compressed air introduces moisture and all the minerals it may contain.

 

[DavidCR]

Ive been checking some info of Amerex.

They mention the standard "C" requirement:

CLASS C FIRES
Electrical Equipment
NO FIRE TEST.
Extinguishing agent is tested for electrical non-conductivity. Extinguisher is
discharged onto a copper target charged with 100,000 volts AC across an air gap of ten inches between the
target and the discharge nozzle. No measurable current can be detected at the nozzle in order to pass the
test. Water based agents must have a conductivity of 1 microseimen or less. If acceptable, “C” Symbol is
added.

So from the lab conditions it looks very safe. (And I´m looking forward to hearing news from "stookey" if he had luck with his calls).

Related to this I want to clarify about the extinguisher requirements for electronic equipment installations, following NFPA 75.

NFPA 75 says:
8.3 Portable Extinguishers and Hose Lines.
8.3.1 Listed portable fire extinguishers of the carbon dioxide type or a halogenated agent type shall be provided for the protection of electronic equipment. The extinguishers shall be maintained in accordance with NFPA 10, Standard for Portable Fire Extinguishers.
8.3.2 Listed extinguishers with a minimum rating of 2-A shall be provided for use on fires in ordinary combustible materials, such as paper and plastics. Dry chemical extinguishers shall not be permitted.

So I understand that you can use CO2, but also you need to use A class to accomplish this double requirement. When we tell that CO" is not enough and suggest to use water extinguishers people hesitate and don´t install it.

So the water mist seem to be a good alternative; clarifying the use of water mist on its shock risk and damage potencial is important for us to sell the idea for offices with important electronic equipment.

 

[stookeyfpe]

David,

Look at my 05 August 09 post @ 13:44. I have additional information for you.

 

[786392]

Stookey has clearly identified in his referred post(De-Ionized water usage)

Best Regards
Qalander(Chem)