Above ground diesel tanks

[inspectored]

Inspected two diesel tanks installed above ground.I was surprised to see everything wired class 1 division 2. Was this an overkill or did the contractor do right? I could not find anything in the NEC regarding wiring around diesel fuels.

 

[ryan_618]

Re: Above ground diesel tanks

You could wire a diesel pump with romex if you wanted to.

 

[derf48]

Re: Above ground diesel tanks

Most inspectors, insurance, fire, and electrical like to require tanks for diesel to be wired per article 514. I fully understand diesel fuel is a combustible liquid and not a flammable liquid, and therefore its presence does not require any classification per 501 and 514.3(B). The problem arises in the interpretation of Motor Fuel Dispensing Facilities, and their intended use, and their actual use. When that tank is filled with a flammable liquid, I didn't say if, the hazards of the electrical system being the ignition source for an explosion are very real.
At the very least, insurance companies like to reduce their risks, and do not like to allow the tanks to be unclassified.

Fred Bender

 

[dillon3c]

Re: Above ground diesel tanks

Originally posted by inspectored:
Inspected two diesel tanks installed above ground.I was surprised to see everything wired class 1 division 2. Was this an overkill or did the contractor do right? I could not find anything in the NEC regarding wiring around diesel fuels.

Inspectored,
I'm just wondering,did these two above-ground tanks..Were the of the "double-walled" construction,or were they single-wall and inside the areas of perminate "containment dikes construction" surrounding these tanks.

And if they were in perminate containment dikes? Was the "dike height" greater that the distance from the tank to the dike, for more than 50 percent of the tank circumferance?

I'm just inquiring into these tanks,and the location,and in the trying to understand "why" these great lengths in wiring methods were deployed in situation of, and location? So I might have a better understanding.

Just what is the ignition point, of this fluid/ vapor?

[ June 16, 2005, 05:53 PM: Message edited by: dillon3c ]

 

[hardworkingstiff]

Re: Above ground diesel tanks

Originally posted by dillon3c:

Just what is the ignition point, of this fluid or vapor?

Fuel oil No.1 has a flash point of 100F to 162F and an ignition tempature of 410F.

Fuel oil No.2 has a flash point of 126F to 204F and an ignition tempature of 494F.

Gasoline has a flash point of -45F to -36F and an ignition tempature of 536F to 853F depending on the octane rating (56-100).

I find it interesting that diesel has a flash point higher than gasoline but an ignition tempature lower than gasoline.

The NEC specifically says liquids with a flash point below 100F are classified. 514.3 (A) states the tanks in question do not need to be wired Class 1 if there are no flammable liquids being handled in the area.

FYI, the state of PA requires all diesel fueling locations to be wired as Classified areas.

 

[dillon3c]

Re: Above ground diesel tanks

hardworkingstiff,
Thank you for taking your time, in investigation.. in reply to my question sir..


-->dillon

 

[rbalex]

Re: Above ground diesel tanks

Originally posted by hardworkingstiff:
...
FYI, the state of PA requires all diesel fueling locations to be wired as Classified areas.

It has been my observation over the years that many individuals are quite competent to install or inspect HAZLOC installations. Its determining whether a location should be classified in the first place that gets messy. All too often locations are grossly overclassified, "just to be safe."

One of my favorite statements in NFPA 497 is:

It is not enough to merely identify a potential source of the combustible material within the building and proceed immediately to defining the extent of either the Class I, Division 1 or Division 2; or Class I, Zone 1 or Zone 2 classified areas.

Unfortunately, this is exactly what most folks do.