Classified Area for Storage of Acetyleye

[mityeltu]

I need some advice concerning the classification of an area (31'x19') where a E-cylinder of acetylene will be stored and piped for a chem lab testing method. I am tasked with installing a cabinet with 480-220 step down transformer and breaker panel within this room. This room will also contain several computer work stations.

It seems to me that this might be classified as Class 1, Div 2. or maybe not even calssified based on the fact that the acetylene will be very unlikely to be present in any concentration high enough to combust. The only thing that worries me is the accident condition. If the regulator becomes inoperable or the valve breaks due to impact, the volume culd quickly rise to a combustible mixture.

What are your thoughts about this?

 

[pete m.]

This room will also contain several computer work stations.

I would ask the design engineer if a classification is necessary. It would seem not if they are putting computer work stations within the room:?

Pete

 

[rbalex]

Compressed acetylene has more issues than electrical area classification and they aren’t in the scope of the NEC. With an explosive range from 2.5 to 99.9% and a minimum ignition energy (MIE) of 0.017 milli Joules (mJ) almost anything can set acetylene off; a high pressure leak is virtually self igniting from air friction.

Assuming the overall installation is compliant with NFPA 55, Compressed Gases and Cryogenic FluidsCode, it’s likely that you don’t have a classified location because it wouldn’t do much good if you did. The same concept is often used where there are ignition sources more likely than the electrical installation to cause ignition. It would be best to get a fire protection expert involved with this one.

 

[mityeltu]

@rbalex

Thank you. I have no idea about the NFPA 55 compliance. I'll contact FP tomorrow as I know he was not at our meeting yesterday. Thank you for your input.