Intrinsic Safety - Aluminum

[zappedagain]

I understand Aluminum is bad in an explosive environment because it can spark when other metals are dragged against it.

IEC 60079-0:2007 clause 8.1.2 states that in 'Group II protection level Ga (ia)' the enclosures can't be more than 10% aluminum. I see Rose Enclosures is selling Aluminum enclosures that they claim are safe for 'ia' applications (

http://www.rose-bopla.com/Prod_Pgs/Ex/Prod_06_Aluminum_Ex_Enclosures.htm).

Am I missing something that Aluminum is safe, or did Rose marketing get a bit overzealous? I notice that the certificates available on the web don't claim 'ia'.

Z

 

[Compositepro]

Most explosion-proof enclosures are cast aluminum. While aluminum can burn it does not spark like steel. It is soft and has high thermal conductivity so the heat generated from friction will tend to be conducted away rapidly. Also, the ignition point for aluminum is above the melting point. Melting also absorbs energy and helps keep temperature down of any aluminum chips. Aluminum reacts with oxygen very rapidly, which might lead one to believe it will burn and spark easily but the oxide the forms on the surface is very effective at protecting it from further oxidation. Iron oxide does not protect the iron underneath.

 

[zappedagain]

Interesting.

IEC 60079-0 Clause 8.1.2 states that Group II Ga enclosures "shall contain not more than 10% in total of aluminum, magnesium, titanium, and zirconium, and not more than 7.5% magnesium, titanium, and zirconium". Are they restricting the combinations, not an individual component (such as Aluminum)?

Z