How To Determine NEC 500 Class & Divs

[Robert Maddox]

How do you determine if presence of liquid (or gas, vapor or other) puts an location into a NEC Hazardous Classified Location?

The owner has provided the Material Data Sheet(s) (MDS)on the fluids.

MDS Section VII: Fire & Explosion Data- list the fluids as NFPA Class IIIB material ? Combustible Liquid with the 320F Flash Point & other data. (In this case the fluids are in sealed containers & pumped thru a piping system to the point of usage).

As I understand it the NFPA Class is not the same as the NEC Class & Division.

Please advise / Thanks

 

[sgunsel]

If all of the liquids are Class IIIB, you don't have to worry since the flash points are well above normal temperatures (assuming they are not heated or in very hot areas, relative to their flash point). The electrical and fluid classifications ARE different.

Class I liquids have flash points that are below 100 degrees F and are considered "flammable liquids."

Class II liquids have higher flash points at or above 100 degrees F and below 140 degrees F.

Class III liquids have flash opints above 140 degrees F.

Class II and III liquids are "combustible liquids." Check NFPA 30 for the details.

Electrical area classifications are: Class I for liquid, Class II for solids, such as combustible powders.

 

[weressl]

How do you determine if presence of liquid (or gas, vapor or other) puts an location into a NEC Hazardous Classified Location?

The owner has provided the Material Data Sheet(s) (MDS)on the fluids.

MDS Section VII: Fire & Explosion Data- list the fluids as NFPA Class IIIB material ? Combustible Liquid with the 320F Flash Point & other data. (In this case the fluids are in sealed containers & pumped thru a piping system to the point of usage).

As I understand it the NFPA Class is not the same as the NEC Class & Division.

Please advise / Thanks

Read NFPA 497.