Portable Fuel Dispensers

[iwire]

A question was asked about portable fuel dispensers on another Forum, it is not getting much response so I thought I would post it here.

We see a few liquid gas storage tanks that hold about 500 gallons of gas and have an electric pump mounted on the top. Inquiring minds want to know how this pump is to be wired. This is usually considered a temporary installation and sometimes is relocated to a new site. The pump has a 6-foot cord on it and will occasionally be plugged into an existing outlet via an extension cord.

Tank

Cord

So are both these units allowed to be cord and plug connected?

 

[Rockyd]

514.11(C) has a FPN - For additional information, see 6.7.1 and 6.7.2 of NFPA 30A-2003, Code for Motor Fuel Dispensing Facilities and Repair Garages.

Personally, I can see this for diesel,however gasoline is a whole seperate issue. The cord cap is short enough that it is within a vapor zone for the fumes. If that sounds remote, think how remote it was to the people who had fires caused by cell phones.

This link may turn up some leads -

http://www.mikeholt.com/mojonewsarchive/USEI-HTML/HTML/GasStationRefuelingFires~20020702.htm

 

[roger]

Bob, I'm not making a statement as to legal or not, but, it seems as though 514.3 and table 514.3(B)(1) would apply to classifying the area around these tanks.

Roger

 

[iwire]

I guess my first question is if the NEC applies to these units anymore than the NEC applies to a cord and plug connected coffee machine.

 

[iwire]

Personally, I can see this for diesel,however gasoline is a whole seperate issue.

My very limited knowledge of this subject lead me to the same conclusion.

Diesel OK, gasoline kind of scary.

 

[rbalex]

The diesel is no big deal.

For the gasoline storage tank/dispenser both NFPA 30 and 30A apply.

?Temporary? is irrelevant. [590.2(A)]
?Portable? is irrelevant. NFPA 30, 30A, and 497 all deal with mobile as well as fixed ?sources.?

The gasoline installation is non-compliant.

So why hasn?t it blown up already?

This is a pretty good example that Division 2 locations are usually benign. Gasoline vapors tend to drop like a rock. With a fairly good prevailing wind it?s likely an explosive mixture wouldn?t get much higher than about 6-12? above grade (that?s why we use 18?-24? as a ?buffer?) Additionally, we would need an electrical failure of the cord/local receptacle because the rest of the installation on the tank does appear to be suitable for Division 2. Of course ?pulling the plug? while the pump is running and a vapor cloud has formed would be pretty risky.

So ? the odds are in your favor ? but if you do have a problem ? it?s likely to be a BIG one.

 

[iwire]

Bob thanks for your input.

So ? the odds are in your favor ? but if you do have a problem ? it?s likely to be a BIG one.

In other words if you have a problem you will probably never know it.

 

[don_resqcapt19]

Bob,

So – the odds are in your favor – but if you do have a problem – it’s likely to be a BIG one.

Do you really think so? I would expect that you would have a flash fire and burn off the vapor cloud, but there would not be enough heat energy to cause any problems with the tank and the fuel in the tank. If you are in the vapor cloud at the time, you will be having a very bad day, but I would not expect a big explosion or sustained fire.
Don

 

[rbalex]

Well...

Well...

I guess it's relative as to whether you think a flash fire is a big enough problem or not.

An explosion would be largely dependent on how much air has entered the tank. A full tank would be relatively unlikely to explode. A nearly empty one could be fairly severe. A sustained fire would depend on many variables, primarily how many volatiles collected in the secondary containment before the ignition.

 

[hockeyoligist2]

A full tank would be relatively unlikely to explode. A nearly empty one could be fairly severe.

The vent valve on the tanks that I have saw have a flame arrestor to prevent an explosion. That appears to be the type they are using.

 

[don_resqcapt19]

Bob,

I guess it's relative as to whether you think a flash fire is a big enough problem or not.

As a firefighter, I don't...that type of fire will be out before we get there.
Don

 

[rbalex]

Bob,

As a firefighter, I don't...that type of fire will be out before we get there.
Don

I?ll buy that. As I said, "big" is a relative opinion. Ultimate severity is based on too many variables to know what would happen.

Part of properly engineering a system is attempting to eliminate or reduce as many variables as possible so that there is a reasonably predictable outcome.

Obviously catastrophic events/failures are often unpredictable and unpreventable; but leaving the installation we have been looking at in a non-compliant condition is unnecessary and irresponsible.