Area Classification (Grain Silo installation)

[pturcotte]

Hi All,

I am trying to understand the area classification Class / Division of the interior of a grain SILO.
I know Area Classification is the work of an expert team, etc. that you need to know other factors like environment, chemicals used, auto-ignition temperature, LEL, UEL, etc.

From my point of view, (same thing in Europe with ATEX) the interior of a Silo is definitely a confined space where we could have a hazardous atmosphere mixture.

I have been told that in America the vast majority of the installations are not even classified!
Is it because of the low exposure time to the risk?

All I want to know is the following:
In the USA do we have Silos / storage grain facilities that are classified areas C2D1 / Zone 20?

In USA NEC 70 Articles 500-516 it tells me it should be classified.
NFPA 499 (DUST) seems to help but article 1.3.3 tells me it does not apply to agriculture grain-handling facilities.

I am a bit lost here...
This is for my understanding and further guidance

Thanks for your help!

pturcotte

 

[petersonra]

The INTERIOR of a grain silo probably does not have much in the way of electrical systems.

 

[don_resqcapt19]

The actual interior of the silos I have worked on has been Class II, Division 1, but typically other than some sensors there is no electrical inside the silo. The grain handling areas associated with the silo have often been Class II, Division 2.

 

[rbalex]

The primary ignition sources in grain elevators are not what electrical equipment is installed, rather what may be overlooked:

Section 500.4:
Informational Note No.x (may be 2 or 3 depending on NEC Edition): For further information on protection against static electricity and lightning hazards in hazardous (classified) locations, see NFPA 77, Recommended Practice on Static Electricity; NFPA 780, Standard for the Installation of Lightning Protection Systems; and API RP 2003, Protection Against Ignitions Arising Out of'Static Lightning and Stray Currents.