Classifying the Classified Area? 500.4

[TrickleCharge]

I have a large manufacturing facility that primarily deals with aerospace products. This large building has several areas that utilizes propane, hydrogen, oxygen, etc. There are also other areas where there is what appears to be a woodshop with saws, etc. ALong with spray areas for painting some of their products. I had requested an area classification study to be submitted and basically I got a response back today that was interesting. The designers are proposing to install large mechanical equipment thruout that will ensure that the areas of concern will have adequate venitlation that includes multiple air changes per hour. They would like to use this in lieu of having the areas as part of a classification study. Is there something that dictates that this would work (maybe in the NFPA) ? Or will the classification study need to be done completely in order to ensure the right wiring methods are done? Input in appreciated!

 

[Smart $]

A classification analysis would be necessary to determine air exchange and filtering levels sufficient enough to render areas unclassified. How do they propose to determine those levels without doing a study?

 

[TrickleCharge]

The is what the EE has given me as a response. I still need to pull our fire code to thoroughly read thru it.

2704.3.1(2)requirement.

Said IFCsection states that if we provide 1 cf of ventilation per minute per sf inthese rooms that any fumes and vapors are therefore diluted to the point thatthe hazardous potential is removed. Our mechanical engineer has confirmedin our worst case scenario, we are providing twice the ventilation required bythis section and in our best case are providing five times the requirement.

Now I am going to have to do some research but I agree. How do I know that what they are installing will meet the requirements without a study that gives me evidence of this?

 

[sgunsel]

The paint booths will be Class 1, Division 1 with adequate ventilation, which is required. See NFPA 33. Also, the areas within 3 feet of any opening will be Class i, Division 2 based on latest NFPA 33. Older versions, which may be in effect, call for larger Div 2 areas. Can't speak for other areas since info is too sparse.

 

[sgunsel]

Per NFPA 33 and article 516, the spray booth requires adequate mechanical ventilation and will be Class I, Division 1. The areas within 3 feet of any spray booth opening are Div 2 based on the latest version of NFPA 33, but older versions and 516 specify larger distances for the Div 2 boundaries. I can't address the other areas since the information provided is too sparse.