Okay, let's break down the NEC's definition in Table 515.3 and apply it to your specific situation with a 5000-gallon tank and associated transfer equipment.

Understanding Table 515.3, 2nd Option: "Outdoor equipment installed where flammable..."

This section deals with the classification of hazardous (classified) locations surrounding outdoor equipment that handles flammable liquids. The key here is the phrase "outdoor equipment." The interpretation of "equipment" is crucial.

Defining "Equipment" in this Context



Broad vs. Narrow Interpretation

The word "equipment" can be interpreted in two ways:

Broad

Encompassing the entire system involved in the storage and transfer of the flammable liquid, including the tank itself.

Narrow

Referring specifically to the pieces of machinery used to actively transfer the liquid (pumps, compressors, hoses, etc.).

NEC Intent

Based on the handbook graphics, the context of Article 515, and common industry practice, the

narrow interpretation is usually the correct one. The NEC is primarily concerned with the source of ignition and the release of flammable vapors. The equipment actively handling the liquid is far more likely to be a source of ignition or a leak than the tank itself (assuming the tank is properly designed, constructed, and maintained).

Applying to Your 5000-Gallon Tank Scenario

In your situation, the "equipment" in Table 515.3, 2nd option, typically refers to the:

Transfer Equipment

This includes:

Pump (if used)

Any pump moving the liquid.

Compressor (if used)

Any compressor used to assist in the transfer.

Piping and Fittings

The sections of pipe and fittings directly connected to the pump/compressor and used to move the liquid during the transfer process.



Hoses

The flexible hoses used to dispense the liquid into smaller tanks.

Valves

Valves controlling the flow of liquid in the transfer system.

Metering Equipment

Flow meters or other devices used to measure the amount of liquid being transferred.

Associated electrical controls and wiring for any of the above components.

The Tank Itself

While the tank itself stores the flammable liquid, it's generally not considered "equipment" in the context of Table 515.3 for the purpose of defining the entire classified zone. However, the tank

IS considered when looking at venting, leaks and other releases that might occur around the tank which would then create a classified area.

Why This Distinction Matters

The classification of hazardous (classified) locations depends on the likelihood of a flammable vapor being present in ignitable concentrations. The transfer equipment is where spills, leaks, and releases are most likely to occur during normal operation. The tank, when properly maintained, is significantly less likely to be a source of vapor release. Therefore, the classified zones around the transfer equipment are typically larger and more encompassing than the classified zones directly around the tank.

Important Considerations and Best Practices


Tank Vents

The tank's vent is a critical point for potential vapor release. Classified zones are always required around tank vents. Refer to Table 515.3 for specific requirements and consult API RP 500 or other relevant standards for guidance.
2.

Leakage

Regularly inspect the tank and all associated equipment for leaks. Address any leaks promptly. A leak will create a classified area.3.

Spill Containment

Implement spill containment measures around the transfer equipment and the tank to prevent the spread of spilled flammable liquids.4.

Specific Flammable Liquid

The specific flammable liquid being handled will influence the classification. Liquids with lower flash points and higher vapor pressures will generally require larger classified zones.5.

Local Codes and Regulations

Always consult and comply with all applicable local fire codes, building codes, and environmental regulations. They may have specific requirements that go beyond the NEC.6.

Qualified Professional

Designing and classifying hazardous (classified) locations requires expertise. It is highly recommended to engage a qualified electrical engineer or consultant who is familiar with hazardous location classification and the relevant codes and standards.

In summary:*The tank itself isn't "equipment" in the same sense as the active transfer components. Focus on classifying the areas around the pump, compressor, piping, hoses, and vents where flammable vapors are most likely to be released. Flag for review