Aboveground Diesel Motor Fuel Facility Classification

[arcolon]

Good day. First time posting to this forum. Have been reading forum for past couple of days looking for some information regarding classification of an aboveground diesel fuel facility. I have read plenty of posts in which it is clearly stated that diesel (only) facilities are not classified. However, my questions arises from NEC 500 where it reads that "combustible vapors" are to be classified as Class I. Diesel fuel falls into "combustible" liquids as per NFPA 30, so do I need to consider these "vapors" in the facility and classified it accordingly? Thanks.

 

[don_resqcapt19]

Given the flash point of diesel, it is unlikely that there will be combustible vapors from the diesel. Diesel is a combustible liquid, but in general you only have classified areas for flammable liquids. As I recall flammable liquids are ones with a flash point of 100? or less and combustible liquids have flash points above 100?F.

 

[arcolon]

My concern came from, primarily, from the NEC statement for Class I locations: "combustible liquid produced vapors". Subsequently, I came across this:

"Flash Point
All flammable liquids have what is called a flash point . The flash point is the minimum tempera- ture at which the liquid gives off a vapor in sufficient concentrations to form an ignitible mixture with air near the surface of the liquid within the test vessel . Various ASTM test methods are used to mea- sure the flash point .
The flash points of gases such as hydrogen and methane are well below zero, sometimes close to absolute zero . The flash points are therefore not usually listed for gases .
A flammable liquid as defined in various codes and standards is a liquid with a flash point below 100? F . Combustible liquids have flash points at or above 100? F . Diesel fuel, which by Federal Regulations has a flash point of at least 100? F, does not normally create a haz- ardous location as defined in the National Electrical Code? because at temperatures below 100? F there is insufficient vapor present to result in an ignitible mixture . However, if the ambient temperature exceeds 100? F, diesel fuel becomes a volatile flammable liquid as defined in Article 100 of the National Electrical Code? and can create a hazardous location ."

Therefore, I will assume that the diesel fuel facility is not classified.

 

[don_resqcapt19]

In general, I agree...you just have to look at the flash points and the expected temperature if the combustible liquid...it only becomes a classified area if you expect that you will have inignitible concentrations of flammable gases.
If this is a fuel dispensing location, look at 514.3(A).

(A) Unclassified Locations. Where the authority having jurisdiction can satisfactorily determine that flammable liquids having a flash point below 38C (100F), such as gasoline, will not be handled, such location shall not be required to be classified.

 

[arcolon]

Thanks.