Fire extinguishers

Ton Cremers <museum-security [at] museum-security__org>

>Sue Dunlap <sdunlap [at] wooster__edu> writes
>
>>We need to equip our special collections area with fire
>>extinguisher.  Our safety officer on campus suggested one that uses
>>water or one that uses powder. ...
>
>In an environment with museum, archive or library collections one
>should *never* use powder. Powder is not only poisonous but
>extremely corrosive. One may say that it will put out the flames but
>that the fire will continue for years.

One respondent to this issue has stated that powder should "never"
be used because it is corrosive and poisonous. There are three
powder types and of these ammonium phosphate types alone could be
considered corrosive but I am not sure if they should be described
as poisonous.

The three powder types are rated as follows in LD50 terms--ammonium
phosphate (3000 mg/kg) sodium bicarbonate (4220 mg/kg) and potassium
bicarbonate (4900 mg/kg) mg/kg is also the same as parts per
million. It is not for me to suggest what level is toxic but it is
certain that in a fire there will be several carcinogenic combustion
gases in the air that will make these numbers look very benign.

I also imagine that fire suppression practice would require the
availability if not mandatory wearing of respiratory equipment, in
anticipation of such combustion toxins and that such equipment would
not allow powders to pass given that it is designed to exclude toxic
gases in a fire.

But the issue here is not about protecting conservators but about
the innocents in their care. Any form of water will destroy or
seriously damage paper based art works. Conservators will have
protected themselves before they combat a fire, the collection has
no defence against water.

When the fire is finally out beware that caffeine has an LD50 of
192.

Andrew Thorn


                                  ***
                  Conservation DistList Instance 21:46
                  Distributed: Thursday, March 6, 2008
                       Message Id: cdl-21-46-006
                                  ***