**LCA**

**INC.**

**LOSS CONTROL ASSOCIATES INCORPORATED**

**FIRE SAFE FUEL FARM OPERATIONS**

**Orville M. "Bud" Slye, Jr., PE, FSFPE**

**Presented at the 30th Annual Airport Conference, Hershey, PA**

**March 6 - 8, 2007**

The storage, handling and use of flammable and combustible liquids
requires effective measures prevent and protect personnel and facilities
from fire and explosion. Experience shows that when safe operating
practices and procedures are not followed, flammable and combustible
liquids can be a significant fire and explosion hazard exposing
facilities to fire damage with a potential for injury to operating
personnel.

This paper examines steps for maintaining or improving fire safety in
flammable and combustible liquid storage tank areas. Observing these key
operating and facility design and safe practices can prevent fires and
prepare for control and extinguishment of fires should they occur in an
airport storage tank facility.

Attachment 1 is a review of typical fires in flammable and combustible
liquid storage and handling facilities which illustrates the hazards and
difficulties inherent in controlling major storage tank fires.

**WHAT STEPS ARE EFFECTIVE**

Effective steps to tank fire safety can be determined through answers to
the following questions:

-   What is in the tank?

-   What type of tank is being used?

-   Where is the tank located?

-   How are spills controlled?

-   How are vents for the tank arranged?

-   How are ignition sources controlled?

-   What fire prevention measures are being used?

-   What fire protection is provided for the tank?

-   What fire safety measures are required for the loading rack?

-   How will an emergency (fire) be handled?

**WHAT IS IN THE TANK?**

The first step is to determine what liquid is stored is in a tank. This
chemical data is essential to understanding the inherent hazards of the
liquid and should include specific data on the chemical and whether or
not the liquid is a flammable or combustible liquid.

Airport storage tanks will most likely to be a flammable or combustible
liquid. However, chemical data is extremely helpful in developing an
effective site fire protection plan. Data related to specific hazards of
fuel stored should include data from the Material Safety Data Sheet
(MSDS) on flash and boiling points, molecular weight, vapor density and
flammable range. Other data; such as whether the chemical is an acid,
base or solvent, or heating or other special measures for safe storage
should be determined.

A review of the definitions for the fire hazard of liquids follows:

**Liquid Hazards**

Key terms that define flammable and combustible liquids fire hazards are
[Flashpoint]{.underline} and [Vapor Pressure,]{.underline} These terms
provide the vital information used for emergency planning and fire
prevention

> [Flashpoint]{.underline} -- This is the liquid temperature at which a
> liquid releases sufficient vapor to form an ignitable mixture with
> air, either near the liquid surface or within a vessel. Flashpoint is
> determined by a flashpoint tester and is the basis for hazard
> classification. There is a direct connection between volatility and
> flashpoint. A liquid with a flashpoint near normal temperatures,
> without being heated, will produce vapor that can be ignited by a
> small ignition source; such as a spark or pilot flame. Flashpoint and
> boiling point temperatures are reduced as altitude increases since
> liquid volatility increases with reduced atmospheric pressure. Liquids
> that are combustible at sea level may be more hazardous as atmospheric
> pressure is reduced.
>
> [Vapor Pressure]{.underline} -- This is the pressure, measured in
> pounds per square inch absolute (psia), exerted by vapor against the
> atmosphere. Just as the atmosphere exerts pressure on the liquid
> surface, the liquid pushes back. Vapor pressure is normally less than
> atmospheric pressure and is a measure of the evaporation or change in
> state from liquid to the gaseous state. This characteristic is often
> termed volatility and liquids that easily evaporate are termed as
> "volatile" liquids. The safety concern is that the higher the vapor
> pressure, the more the liquid evaporates and the lower the boiling
> point, resulting in more vapors within an increased risk.

**Liquid Classifications**

A uniform system of defining and classifying flammable and combustible
liquids has been developed for application of fire and safety code
requirements. Flammable liquids are Classified as Class I liquids and
combustible liquids are classified as Class II or III liquids.

> [Flammable Liquids]{.underline} - Any liquid with a closed-cup (type
> of flashpoint test) flashpoint below 100^0^F (37.8^0^C) and a Reid
> vapor pressure not exceeding 40 psia (2068 mm H~g~) is a flammable
> liquid. These liquids are referred to as Class I liquids. Liquid
> classifications are further divided into three sub classifications as
> follows:

-   Class IA liquids have flashpoints below 73^0^F (22.8^0^C) and
    boiling points below 100^0^F (37.8^0^C).

-   Class IB liquids have flashpoints below 73^0^F (22.8^0^C) and
    boiling points at or above 100^0^F (37.8^0^C).

-   Class IC liquids have flashpoints at or above 73^0^F (22.8^0^C), but
    below 100^0^F (37.8^0^C).

Gasoline, Jet B, and JP 4 are typical examples of a flammable liquid.

> [Combustible Liquid]{.underline} - A liquid with a closed-cup
> flashpoint at or above 100^0^F (37.8^0^C) is a combustible liquid.
> These liquids are referred to as either a Class II or Class III
> liquids based on the following:

-   Class II Liquids have flashpoints at or above 100^0^F (37.8^0^C) and
    below 140^0^F (60^0^C).

-   Class IIIA Liquids have flashpoints at or above 140^0^F, but below
    200^0^F (93^0^C).

-   Class IIIB Liquids have flashpoints at or above 200^0^F (93^0^C).

> Class IIIB liquids are generally not included in the scope of codes
> and standards with the exception of the International Fire Code which
> does not differentiate between Class IIIA and IIIB liquids requiring
> the same safety measures despite the lower hazard. Fuel Oil No. 2,
> kerosene, and some Jet A and A-1 fuels are typical examples of a
> combustible liquid.

**WHAT TYPE OF STORAGE TANK IS BEING USED?**

Fuel storage tanks can be either a horizontal or vertical configuration
and are normally designed to operate at atmospheric pressure. Tanks that
are pressurized to facilitate dispensing or some other purpose are
rarely used for fuel storage.

A number of options may be used to arrange storage tanks in a facility.
Some key factors in tank design and arrangement include:

-   Tanks are designed for either installed above or below ground
    installation.

-   Tanks can be either vertical or horizontal configuration.

-   Tanks are most likely to be metal construction, but concrete and
    fiberglass tanks for underground are common.

-   Tanks may be lined with corrosion resistant materials; such as
    plastic for protection from corrosives; however, this would be
    unusual for aboveground fuel tanks.

-   Tanks can be double containment metal tanks to contain leaks from an
    inner tank, or more likely, will be located in a dike or spill
    collection basin.

-   Smaller tank systems are available with an integral spill basin,
    pump and hose reel for product transfer.

Since aboveground vertical and horizontal tanks are the most common
tanks, protective measures associated with these tanks will be discussed
in this paper.

**Atmospheric Above Ground Storage Tanks**

Atmospheric storage tanks operate at pressures ranging from atmospheric
up to and including 1.0 psig. Larger atmospheric storage tanks may have
a maximum operating pressure below 1 psig in order to eliminate roof
plate weld stress from continuous exposure to higher operating pressure.

Some locations may have Low Pressure Tanks designed to operate at
pressures greater than 1 psig but not more than 15 psig. The primary
differences between an atmospheric and low pressure tank is that
protection is provided to the low pressure tanks to prevent explosive
tank failure when exposed to fire.

Atmospheric tanks can be vertical or horizontal tanks. Storage tanks are
defined in NFPA Standard 30, as any vessel having a liquid capacity
exceeding 60 gallons, intended for fixed installation and not used for
processing.

**Atmospheric Tank Design Standards**

The most commonly used standards for the design and construction of
atmospheric storage tanks are listed in Table 1. The definitive standard
that is commonly used for fire safety in the handling, storage and use
of flammable and combustible liquids is the National Fire Protection
Association, Standard 30, *The Flammable and Combustible Liquids Code.*
Most building and fire codes and the standards developed by other
organizations use NFPA 30 as the definitive standard for flammable and
combustible liquids fire safety.

**Vertical Storage Tanks**

The configuration of a vertical aboveground tank design can be either an
[open top]{.underline} with the roof floating on the stored liquid or a
[fixed roof]{.underline}. The safe design of floating roof tank offers a
considerable level of fire safety over other vertical tank designs. As a
result, fire codes allow closer spacing between floating roof tanks and
for separation from adjacent properties or operations providing a cost
advantage in tank farm layout and arrangement.

> [Open Top Tanks]{.underline} -- An open top tank has a floating roof
> exposed to the environment. Open top tanks have a low fire potential
> with the most likely fire exposure being a limited amount of liquid in
> the seal area between the shell and the roof. The fire potential is
> very low this area, which is the only space on the tank roof where an
> ignitable mixture normally exists. Fires in the seal area can be
> readily extinguished by a hose line or a portable extinguisher on
> small to medium sized tanks; while a fixed foam system is normally
> installed on larger tanks.
>
> Lightning is the most prevalent ignition source for a seal area fire
> and is preventable by installing a bond between the roof and the
> shell. Routine inspection of lighting protection bonding straps is
> required to assure that protection measures are in place and not
> damaged by roof movement, maintenance activities or by weather
> effects. Another ignition source is hot work on the roof or near the
> seal area without proper precautions to prevent ignition. Fire in a
> dike area near or impinging on the tank can ignite seal area vapors.
> Fire activities should minimize tank shell fire impingement to prevent
> fire spread to the seal area.
>
> [Covered Floating Roof Tanks]{.underline} -- This tank design is a
> floating roof which is protected by another fixed roof for weather or
> environmental control. During filling, an ignitable mixture can be
> present in the vapor space between roofs. Gas tests should be
> conducted before personnel entry or during hot work in the vapor space
> above the floating roof. Personnel entries into the vapor space should
> be conducted as a confined space entry. It is possible for the
> floating roof to be less substantial or stable than a standard open
> top floating roof tank. Where the roof is a pan configuration, see
> discussion below on Fixed Roof Tanks.
>
> [Fixed (Cone) Roof Tanks]{.underline} -- Fire exposure to a tank
> increases internal pressure from boiling liquids or, very rarely, from
> an internal explosion. Fixed roof tanks are designed to vent during an
> emergency by opening weak roof-to-shell joint seams at the point of
> panel attachment to the tank shell. The weak seam allows the roof to
> tear free from the tank shell to prevent failure of other joints.
>
> An internal pan roof floats on the liquid. These roofs are typically
> constructed of honeycombed aluminum panels, metal on plastic floats or
> similar style roof design. This type of roof lacks substantial support
> and stability inherent in an open or covered floating roof tank and is
> not fire resistant. A common failure mode for this style of roof is
> tilting or sinking resulting in fire exposure to the tank. This style
> of roof is commonly used for emission control purposes, but is
> unlikely to have a substantial effect on tank fire safety.
> Installation of a pan roof can also result in blocking application of
> foam during a fire, especially where the tank is protected by
> sub-surface foam and/or the roof sinks blocked foam inlets

**Horizontal Storage Tanks**

Horizontal tanks are commonly cylindrical in shape with flat ends and
are usually mounted on legs or steel or concrete support structure. The
structure may not be fire proofed or protected to prevent failure when
fire exposed. Supports over 12 inches in height should be protected by
fire proofing materials or water spray protected to prevent catastrophic
failure where fire exposed.

Emergency venting of horizontal tanks is provided by vent devices
similar to those for fixed roof vertical tanks. In addition to emergency
vents, pressure relief vents protect the tank from overpressure during
tank filling and from collapse during liquid discharge from the tank.

Secondary tanks are becoming a common means of enclosure of the primary
tank to achieve spill or leak containment. Small horizontal tank sets
are available which include containment dikes sized for the tank. Some
tanks are capable of being moved by a forklift truck. When installing
portable tanks near buildings, sufficient clearance from the exposed
building should be provided to assure that a tank fire does not expose
adjacent equipment or the building. Tanks and their contiguous spill
basins should be carefully evaluated to assure that emergency vents are
sized to prevent tank collapse or failure during fire exposure.

**WHERE ARE THE TANKS LOCATED?**

The location of a tank facility has a direct impact on fire safety. The
tank location should be arranged to prevent exposing fires from
spreading into the tank farm; and conversely adjacent buildings should
be located so that a fire in the tank farm will not spread off of the
property or spread to adjacent tanks.

NFPA 30 contains requirements for spacing between tanks and to or from
property lines and adjacent structures and facilities. These distances
are minimal and increased spacing may be beneficial when constructing a
new facility since increased separation will reduce risk of fire
exposure. Reference should be made to NFPA 30 minimum spacing
requirements during emergency planning to prepare for exposure
protection during fire fighting operations.

Accessibility is a key factor in effective storage tank fire control.
Fire fighting operations require separation from the tanks in order to
avoid fire exposure to fire equipment and personnel. Where subsurface
inlets are installed for tank fire control, access to foam inlets should
be outside the dike area or in an easily accessible location where tank
shell connections are utilized.

Where foam trucks and other portable equipment will be used for fire
fighting operations, the tank farm should be accessible from at least
two directions. The ideal arrangement provides complete access around
the tank dike areas with roads and access points sufficiently wide for
fire trucks. Vehicles should be able to move by fire trucks parked at
fire department connections to foam systems and at hydrants.

**HOW ARE SPILLS CONTAINED OR CONTROLLED?**

Product spills occur when tanks are overfilled, as pump seals or
pipeline flanges leak or holes occur in tank shells. The ground area
around the tanks should be arranged to direct spilled liquids away from
the tanks to lower sections of dike areas, into diked impoundment areas
or to a basin, remote impounding. If space is available in a tank farm
the most desirable and safest arrangement is a containment area that is
remote from equipment, tanks, and exposed structures.

Dike area drains should be a fire sealed and extend through the dike
wall. Each drain valve should be clearly labeled and located outside the
dike discharging to the site drainage system for treatment of small
spills in an environmentally correct manner.

**HOW DOES THE TANK VENT IN AN EMERGENCY?**

Tanks exposed to a fire in contact with or near the tank shell will have
an increase in pressure as tank contents are heated. Tank vents are
arranged to facilitate pressure changes as liquid is added or withdrawn
or changes resulting from atmospheric temperature and pressure. Fire
exposure to an aboveground tank heats the contents to their boiling
point which substantially increases tank pressure. Fire exposure also
can damage tank supports and unwetted portions of the tank shell.
Increased pressure can be controlled either by tank design or by tank
vent devices. Emergency pressure relief through tank design includes
lifter or floating roofs, a weak roof to shell tank roof seam or
emergency vent devices. Without pressure relief the tank is likely to
rupture randomly, or even rocket as a result of a failure of the shell
to bottom seam.

Liquids, such as LPG in pressure tanks having boiling points below
atmospheric temperature have relief valves which are set to maintain the
tank at a higher pressure setting. Fire exposure to the portions of the
vessel shell not in contact with the liquid can cause a loss of vessel
shell strength as the fire heats unprotected metal to failure. The
resulting metal tear is likely to completely encircle the tank and to
release tank contents; often with pieces of the tank rocketing
explosively away from the vessel. This action, known as a Boiling Liquid
Expanding Vapor Explosion (or BLEVE), is the catastrophic failure of a
container into at least two major pieces and simultaneously releasing
the contained liquid which is at a temperature well above its boiling
point at normal atmospheric pressure. BLEVES have occurred when LPG
filled railroad cars or storage tanks were fire exposed. Pressurized
tanks may be used for storage of LPG for heating or similar uses in an
airport.

**WHAT FIRE PREVENTION MEASURES ARE BEING USED?**

Precautions need to be taken to prevent ignition of flammable vapors
through the control of open flames, lightning, hot surfaces, radiant
heat, smoking, cutting and welding, static electricity, electrical
sparks and stray currents, heating equipment and other ignition sources.

Smoking should be confined to designated and properly identified areas.
Welding, cutting and similar spark producing operations should only be
conducted under a strict hot work control system. Adequate controls for
hot work should include comprehensive testing of the area to assure that
flammable vapors are not present in the work area. All combustibles that
may be ignited by hot sparks from hot work should be removed or properly
protected to prevent against ignition.

Static electricity controls start with proper operating practices and
controls to minimize the potential for generation of static electricity.
Metallic equipment should be bonded or grounded when used in areas where
an ignitable mixture could be present. All non-metallic equipment and
piping, where an ignitable mixture could be present, should be carefully
reviewed to assure that the generation of static is not a possibility.

Electrical equipment should be designed, selected and installed to meet
requirements of NFPA 70, *The National Electrical Code*. In areas where
there is likely to be the presence of an ignitable vapor mixture, the
equipment should meet requirements for electrical area classification in
accordance with NFPA 30 and 70.

NFPA 30 requires an engineering evaluation of the installation and
operation to determine the extent of fire prevention and control
measures followed by the application of sound fire protection and
process engineering principles. The analysis is required to include:

1\) Analysis of fire and explosion hazards of the facility;

> 2\) Analysis of local conditions, such as exposure to and from
> adjacent properties, flood potential or earthquake potential; and

3\) Fire department or mutual aid response.

**WHAT FIRE PROTECTION MEASURES ARE PROVIDED?**

Fire Protection measures for storage tanks should be based on the
relative hazard of the stored materials instead of on every tank
regardless of hazard. Consideration should be given to the relative
hazard of the stored materials, the hazards inherent in the type of
tanks in the storage facility, and the availability of public and
private fire fighting support and equipment.

NFPA 30 requires that a fire-extinguishing system be provided for
vertical atmospheric fixed-roof storage tanks storing Class I flammable
liquids larger than 50,000 gallons (1190 bbl) capacity. Fire Protection
is especially desirable where tanks are located in a congested area with
an unusual exposure hazard between the tank and adjacent property. Fixed
roof tanks storing Class II or III liquids at temperatures below their
flashpoints and floating roof tanks storing any liquid, generally do not
require protection when the tanks are installed in compliance with
spacing and installation requirements of NFPA 30.

**Relative Hazard of Stored Materials**

Class IIB liquids (flashpoints above 200^0^F) can be safely stored
without fire protection systems unless the oils are being heated to or
above their flashpoint. Tank spacing, containment measures and fire
extinguishing systems are not required by most codes for combustible
liquids with a flashpoint of 200^0^F or above. A low curb or other spill
control means should be provided and spacing for maintenance activities
should be provided between tanks.

Class III liquids (flashpoints over 140^0^F and below 200^0^F) are not
normally fire protected, except when heated to or above their
flashpoints. Unheated tanks in this category will usually not require
foam protection unless there are unusual conditions such as:

-   There is a potential that the tanks will be filled with materials
    with a flashpoint below 140^0^F.

-   Overheating of the tanks can occur resulting in storage temperatures
    exceeding the flashpoint of the stored materials.

-   The tank is vulnerable to fires involving adjacent equipment or
    facilities.

Tanks containing flammable liquids, those with a flashpoint below
140^0^F, may require fire protection. Industry experience with gasoline
and other flammable liquids stored in open top or covered floating roofs
show minimal fire experience; and with good spacing between tanks and
minimal fire exposure, these types of tanks storing flammable liquids
have a low fire hazard. NFPA 30 requirements for protection for Class I
liquids was discussed previously.

**Basis for Foam Protection Requirements**

Evaluate the storage tank facility for relative fire risk and associated
foam protection requirements. As noted above, NFPA 30 contains
requirements for foam protection for Class I liquids. Extinguishment of
the largest cone roof tank fire is typically the design basis for a tank
foam system. Cone roof tanks are typically protected by sub-surface foam
systems, unless the tanks containing polar solvents and alcohol
resistant foams are not available or pan roofs are installed in the
tank. Open-top floating roof tanks require protection from rim fires.

**Foam Application**

Foam application rates should be at least the minimum rates required by
NFPA Standard 11, *Low, Medium and High Expansion Foam*. Foam
application, once started, is required to be applied continuously at the
minimum recommended rate and duration in order to extinguish a tank
fire. Intermittent or shortened foam application without fire
extinguishment results in foam breakdown and destruction of any
established foam blanket. Additional foam concentrate will be required
to re-establish the lost foam blanket and blanket the entire liquid
surface. The NFPA II recommended quantities of foam-producing material
are sufficient for fire extinguishment, however, application of
additional foam-producing concentrate can decrease the time for fire
extinguishment.

> [Cone Roof Tanks]{.underline} -- Foam application on cone roof tank
> fires can be achieved by various methods: subsurface foam injection;
> portable foam towers; fixed foam chambers mounted on the tank shell or
> portable hose streams or monitors. Application by subsurface
> injection, towers or fixed foam chambers is applied at a rate of 0.1
> gallons per minute per square foot and application rates for portable
> hose streams or monitors is 0.16 gallons per minute per square foot.
> Fires in more volatile materials such as gasoline may require higher
> rates of up to 0.2 gallons per minute per square foot, depending on
> pre-burn time
>
> [Cone Roof Tanks with Internal Floating Covers (Pans)]{.underline} --
> Foam protection using an over-the-top system designed for coverage of
> the entire tank liquid surface area of the tank should be provided
> when internal covers are a pan-type design, constructed of combustible
> materials, or are thin aluminum skin and floats. Subsurface
> applications are not recommended since the inlets may be blocked by a
> sunken roof and thus prevent foam application into the tank.
>
> [Open Top Floating Roof Tanks]{.underline} - Open-top floating roof
> tanks are protected for seal fires. For tanks up to 150 feet in
> diameter, foam can be applied from portable hose lines supplied from
> fire trucks for tanks up to 120 feet diameter and from a foam solution
> standpipe on tanks 120 to 150 feet diameter. Tanks over 150 foot
> diameter are more suited for a fixed foam application system for rim
> fire protection. The rim fire protection system (catenary design) can
> be supplied foam from a fire truck or from a piped foam system. The
> rim seal protection system should meet NFPA 11 requirements for
> application rate dependant upon the type of seal and foam outlet
> arrangement.
>
> Portable hose streams should be a minimum of two 50 -- 60 gpm foam
> nozzles supplied from foam fire trucks or a foam-proportioning system.
> A foam dam is required when hose streams are used for protection when
> the seal is a tube seal or includes metal weather shields or a
> noncombustible secondary seal.
>
> [Covered Floating Roof Tanks]{.underline} *-* When the floating roof
> in a covered floating roof tank is a steel floating roof of the single
> or double-deck design, a foam system is normally not required due to
> the low risk of a fire inherent with this tank design. However, other
> styles and designs for covered floating roof tanks should be provided
> with foam systems for control of seal fires meeting requirements for
> open top floating tanks when the tank diameter exceeds 150 feet or
> when the tank has significant value or risk to the site.

**Portable Monitors and Hose Nozzles**

Portable foam monitors and hose streams have limited ability to
extinguish tank fires. Protection from monitors is generally ineffective
on cylindrical or cone roof tanks over 60 feet in diameter and hose
lines are not effective for tanks over 30 feet in diameter and over 20
feet high. While foam monitors have been successful in extinguishing
fires that involved tanks up to 130 feet in diameter and 42 feet high,
the use of large monitors should not be depended upon as a primary means
for extinguishment of large cone roof tank fires.

There are substantial limitations when using portable monitors or hose
streams for tank fire extinguishment. Low tank product levels, wind
effects and intense fire updrafts can prevent foam from reaching the
product surface and forming a foam blanket. Foam requires continuous and
even application to establish a foam blanket, since foam streams should
be directed against the inner tank shell so that the foam flows gently
onto the burning liquid surface without undue submergence. Due to the
difficulties in use of portable foam devices -- hose and monitor nozzles
-- a foam solution rate of at least 0.16 gallon per minute per square
foot of tank liquid surface areas is required. Due to the difficulty in
directing the foam into the narrow annular space of the roof seal, and
the potential to sink the roof, ground level monitors are not
recommended for seal fires. Often poorly executed monitor application
for foam fires has resulted in roofs sinking or tilting, which results
in a larger fuel surface fire in the tank. Boom mounted nozzles on fire
trucks may be useful in application of foam providing there is foam
truck accessibility and the tanks are relatively small in diameter.

**Water Supply**

Subsurface injection or topside foam application rates are determined by
the tank size, the application rate and the amount of water required for
cooling the tank and exposures. For flammable and combustible liquids
the water application rate for subsurface or topside application is
typically 0.1 gallon per minute per square foot. Additional water will
be required for foam hose streams and water cooling streams.

> [Water Requirements]{.underline} - The following example illustrates
> the additive quantities of water required to meet the full water
> demand for tank protection:

[*Example 1 --* 40 ft diameter Tank]{.underline}

Required Foam Solution - 125 gpm

Foam Hose Streams 50 gpm

Water Cooling Streams 500 gpm

Total Water Requirement 675 gpm

Foam Solution Rate (@0.1 gpm/sq ft) = 176 gpm

[*Example 2 --* 150 ft diameter Tank]{.underline}

Required Foam Solution - 1,767 gpm

Foam Hose Streams 150 gpm

Water Cooling Streams 1,000 gpm

Total Water Requirement 2,900 gpm

Foam Solution Rate (@0.1 gpm/sq ft) = 1,917 gpm

> [Water Pressure]{.underline}- Water cooling streams can be taken
> directly from fire hydrants, however, hydrant residual pressure less
> than 80 psig will require fire truck booster pumps to supply hose
> streams. As an example, a 250 gpm cooling stream will reach over the
> curb angle of a 75 foot high tank from a horizontal distance of 65
> feet with 50 psig nozzle pressure using a solid stream nozzle of 1 1/8
> inches. Minimum residual hydrant outlet pressure should be 80 psig in
> order to supply 50 gpm through 250 feet of 1 ½ inch fire hose.
>
> Foam hose streams are typically supplied from foam fire trucks. When a
> fixed foam system is installed, foam hydrants might be capable of
> supplying foam hose streams. Alternatively, foam nozzles can be
> equipped with pickup tubes, but these require foam liquid in 5 gallon
> containers to be available at the nozzle in easily handled containers.
> Ranges of foam nozzles typically rated at 100 psig vary based on the
> manufacture. The effective range for 100 gpm nozzles on 1 ½ inch hose
> lines can vary from 50 to 65 feet depending on flow and inlet pressure
> while larger 2 ½ inch nozzles have ranges from 60 to 120 feet.
>
> [Fire Mains and Hydrants]{.underline} -- The storage tank farm fire
> water demand is based on the quantity of water required to protect the
> largest cone roof tank, plus the water needed for cooling hose streams
> to protect exposed tanks or adjacent facilities. As a general rule of
> thumb sufficient water will be required to extinguish a fire in the
> largest tank, plus the amount of water required for protection of
> unshielded neighboring tanks. Water pressure in the hydrants and the
> water system should be adequate to provide 100 psig residual pressure
> when flowing sufficient water to supply cooling streams directly from
> hydrants.
>
> A fire water system looped around the facility provides flexibility
> during use. Isolation of damaged sections without impairment of the
> entire fire protection system can be aided by provision of division
> valves arranged so that any section of the fire main grid or loop may
> be removed from service while fire water continues to be supplied for
> tank fire protection. System hydraulic calculations can assist in
> determining that there is an adequate water flow rate. The number of
> valves needed for system reliability should be based on no more than
> six hydrants out of service as a result of a single main break.
> Hydrants should be provided in sufficient number to permit fire
> fighting operations regardless of wind direction and sized to supply
> 500 gpm from a 4 inch hydrant and 100 gpm from a 6 inch hydrant.
> Outlets should be two hose connections and a large diameter 5 inch
> minimum fire truck connection outlet.
>
> Hydrants should be located outside of tank dike walls, adjacent to
> roadways and a minimum of 1 tank diameter; but no less than 50 feet
> from the tank shell to avoid heat exposure to fire trucks when
> connected to the hydrant. Hydrant outlets should be no more than 6
> feet from the approach of a fire truck to the hydrant. The local fire
> authorities should be consulted to assure that truck connections, hose
> threads and location are compatible with the equipment used by the
> mutual aid fire fighting organizations in your area.

**Tank Protection Using Passive and Active Systems**

Fire exposure protection can be provided by passive systems including
fire proof insulation, concrete encasement or similar insulation
materials applied on the tank shell. Protection should be provided by
methods tested by the Underwriters Laboratories (UL) to a 2 to 4 hour
hydrocarbon fire exposure in order to protect the tank from direct
hydrocarbon fire exposure. Insulation systems are difficult to apply to
vertical tanks and are more suited for horizontal vessels. Careful
consideration should be given to the type of fire exposure and potential
fire duration when applying hydrocarbon fire exposure insulation
methods.

Active tank protection systems include water spray systems for
application of water onto the vessel shell. This type of system,
designed to requirements of NFPA 15, *Water Spray Systems*, typically
applies water through a system of specially designed nozzles at minimum
application rates of 0.15 to 0.40 gpm/square foot of vessel surface
area. Water spray systems require a strong fire water supply and a means
to automatically apply the water in order to avoid delay which will heat
tank contents and possible result in tank rupture.

**IS THE TRUCK LOADING RACK PROTECTED?**

The potential fire hazards of tank truck loading and unloading
facilities include open filling through truck domes, making and breaking
of fill connections, and compartment overfilling leading to a product
spill. Ignition sources that may be present include truck engine
ignition systems and electrostatic charges.

**Electrostatic Ignition Prevention**

Prevention of electrostatic ignition requires bonding of the fill system
to the tuck to ensure that equipment is at the same electrical potential
to prevent sparking.

The term "switch loading" is the loading of a low or intermediate vapor
pressure product into a compartment that contains flammable vapors from
previous use. An example would be loading a combustible liquid, such as
kerosene, fuel oil, or high flashpoint Jet A into a compartment that had
contained motor or aviation gasoline on the previous load.

The procedure to be followed in switch loading should be posted at the
loading rack. Conductivity additives can be added to low-conductivity
products to diminish the potential for static ignition. Loading controls
required to minimize the possibility of electrostatic ignition should be
well communicated to loaders and/or drivers to assure maximum safety of
rack operations.

**Spills**

Since ignition sources are always present, there is the potential for
flashback and fire in the event of a major spill of volatile product. A
drainage system should be provided to permit such spills to be flushed
and drained away from the rack to a sate location without entering a
public sewer system. Water steams can be used to divert spills from the
truck loading area and foam can be used to blanket large spills and to
prevent ignition until cleanup can be achieved.

To minimize spills and associated hazards, an emergency shutdown system
for pumps and product shutoff valves should be provided in all product
lines to the rack area for remote fuel source shut off. Hand operated
valves should be at least 50 feet from the nearest truck loading
position Power operated valves can be closed by emergency shutdown
switches at the rack loading position from remote locations and by fire
detection devices. Fire protection systems should be interlocked on
operation to shut down product flow.

Drainage systems should be provided to remove spills from the loading
area into a spill retention area or tank located away from the rack. The
drainage system should include fire stops and should be connected to
collection and separation systems provided to prevent flow into public
sewers or other disposal units.

**Loading Rack Fire Protection**

A fire protection system should be considered for loading racks handling
flammable liquids, especially where switch loading is conducted.
Protection is particularly desirable for those locations where the
driver is the sole attendant during loading, where there are potentially
hazardous conditions at the rack or fire exposure to the rack exists.

Fire protection may be provided by a fixed foam water or dry chemical
fire protection system. System design should be compliant with NFPA 11
for Foam Protection and NFPA 17, *Dry Chemical Extinguishing Systems*
for dry chemical systems.

Automatic fire detection systems should be considered for racks that are
not constantly attended by personnel other than the driver during
loading operations. The systems can be arranged to actuate all loading
rack fire extinguishing systems. The automatic detection system should
consist of line or spot-type heat detectors or photoelectric detectors
installed in accordance with NFPA 72, *The National Fire Alarm Code*.
Manual actuation should also be provided for the rack protection system
so that personnel can actuate the system. Product flow to the rack
should be shut down on operation of the fire alarm system.

**HOW WILL AN EMERGENCY BE HANDLED?**

Emergency planning can never be successful if it is started when the
facility is on fire. Emergency planning requires a great deal of effort
including time to develop an emergency plan, arrange mutual aid
agreements, identify sources of foam and other fire fighting chemicals,
develop procedures for all operations and plans for controlling
emergencies, and last but not least, conducting drills to practice
emergency plans and procedures.

**Planning for the Emergency**

A comprehensive plan should be developed with participation of all
parties involved in emergency operations for storage, handling and use
of bulk quantities of fuels. Guidance on development of emergency plans
for fighting fires in atmospheric storage tanks can be found in API
Recommended Practice 2021, *Management of Atmospheric Storage Tank
Fires*.

**CONCLUSION AND SUMMARY**

Past experience has proven that storage and handling of flammable and
combustible liquids can be conducted without fire losses to storage
tanks. Operators should be aware of the hazards associates with
operation of storage tanks and fuel transfer. Proper precautions begin
with the design and installation of storage tanks taking into account
the accepted safety measures for the use, storage and handling of
flammable and combustible liquids.

Application of effective fire protection to the protection of storage
tanks and facilities related to handling fuels at an airport can be
achieved through an evaluation of fire hazards and installation of
protective measures and practices. The facility designer has available a
number of tools to provide a fire safe facility including good
engineering practices as outlined in NFPA Standards.

**REFERENCES**

1\. *Fire Investigation Report, Tank Farm Fire, Denver, CO. November 25,
1990*, M.S. Isner, National Fire Protection Association

2\. *Aviation Accident Report, Fuel Farm Fire at Stapleton International
Airport, Denver CO, November 25, 1990*, NTSB/AAR-91/07. Adopted October
1, 1991 Notation 5576

3\. *Truck Loading Rack Safety, Loss Prevention and Protection*,
Industrial Risk Insurers, 1983.

4\. *Tank Fires, Review of Fire Incidents 1951 -- 2003*, Brandforsk
Project 513-021, SP Swedish National Testing and Research Institute, SP
Report 2004:14

5\. *Interim Study-Prevention and Suppression of Fires in Large
Aboveground Atmospheric Storage Tanks*. American Petroleum Institute,
API Publication 2021A, July 1998, prepared by Loss Control Associates,
Inc., O.M.Slye, Jr, PE

6\. *Dark Skies Over England, Explosion, Flames Destroy U.K. Fuel
Storage Depot,* Kevin D. Westwood, Industrial Fire World,
January/February 2005.

7\. *NFPA Documents Causes of AST Fires*, R. Benedetti, NFPA Staff
Liaison NFPA 30, Tank Talk, Steel Tank Institute, March/April 1994.

8\. *The Lastfire Project (Large Atmospheric Storage Tank Fire
Project***)**, Dr. Niall Ramsden, fs-world.com, undated.

9\. *Lastfire Project, Review of Escalation Mechanisms,* June 1997.

10\. *Buncefield -- Anatomy of a disaster*, Industrial Fire Journal,
January 2006.

11\. *Fire, water & pollution -- Buncefield incident post-mortem,*
Industrial Fire Journal, April 2006

12\. *Management of Atmospheric Storage Tank Fires,. Recommended
practice 2021*, American Petroleum Institute, Fourth Edition, May 2001.

13, *Guidelines for Technical Planning for On-Site Emergencies*,
American Institute of Chemical Engineers.

14\. 1910.38, Employee Emergency Plans and Fire Prevention Plans,
Occupational Safety and Health Administrations, US Department of Labor.

15\. API Recommended Practice 2021, *Management of Atmospheric Storage
Tank Fires.*

**NFPA PUBLICATION STANDARDS LIST**

1\. NFPA 11, *Standard for Low-, Medium-, and High-Expansion Foam*, 2002
Edition.

2\. NFPA 15, *Standard for Water Spray Fixed systems for Fire
Protection*, 2001 Edition.

3\. NFPA 17, *Standard for Dry Chemical Extinguishing Systems*, 2002
Edition.

4\. NFPA 30, Flammable and Combustible Liquids Code, 2003 Edition.

5\. NFPA 70, National Electrical Code®, 2002 Edition.

6\. NFPA 72, National Fire Alarm Code, 2007 Edition

7\. NFPA 1561, *Fire Department Incident Management System*, 2005
Edition.

**TABLE 1 - STORAGE TANK STANDARDS**

+------------------------------+---------------------------------------+
| **STANDARDS ORGANIZATION**   | **STANDARD TITLE**                    |
+------------------------------+---------------------------------------+
| Underwriters Laboratories    | UL 142, *Standard for Steel           |
| Inc.                         | Aboveground Tanks for Flammable and   |
|                              | Combustible Liquids*;                 |
|                              |                                       |
|                              | UL 58, *Standard for Steel            |
|                              | Underground Tanks for Flammable and   |
|                              | Combustible Liquids*;                 |
|                              |                                       |
|                              | UL 80, *Standard for Steel Inside     |
|                              | Tanks for Oil Burner Fuel*;           |
|                              |                                       |
|                              | UL 1316, *Standard for Glass-Fiber    |
|                              | Reinforced Plastic Underground        |
|                              | Storage Tanks for Petroleum Products, |
|                              | Alcohols and Alcohol-Gasoline         |
|                              | Mixtures*;                            |
|                              |                                       |
|                              | UL 1746, *Standard for External       |
|                              | Corrosion Protection Systems for      |
|                              | Steel Underground Storage Tanks*;     |
|                              |                                       |
|                              | UL 2080,*Standard for Fire Resistant  |
|                              | Tanks for Flammable and Combustible   |
|                              | Liquids*;                             |
|                              |                                       |
|                              | UL 2085, *Standard for Protected      |
|                              | Aboveground Tanks for Flammable and   |
|                              | Combustible Liquids*.                 |
+------------------------------+---------------------------------------+
| American Petroleum Institute | API Specification 12 B, *Bolted Tanks |
|                              | for Storage of Production Liquids*;   |
|                              |                                       |
|                              | API Specification 12 D, *Field Welded |
|                              | Tanks for Storage of Production       |
|                              | Liquids*;                             |
|                              |                                       |
|                              | API Specification 12 F, Shop Welded   |
|                              | Tanks for Storage of Production       |
|                              | Liquids;                              |
|                              |                                       |
|                              | API Standard 620, *Recommended Rules  |
|                              | for the Design and Construction of    |
|                              | Large, Welded, Low Pressure Storage   |
|                              | Tanks*;                               |
|                              |                                       |
|                              | API Standard 650, *Welded Steel Tanks |
|                              | for Oil Storage.*                     |
+------------------------------+---------------------------------------+
| Petroleum Equipment          | PEI RP 100, *Recommended Practices    |
| Institute                    | for Installation of Underground       |
|                              | Liquid Storage Systems*;              |
|                              |                                       |
|                              | PEI RP 200, *Recommended Practices    |
|                              | for Installation of Aboveground       |
|                              | Storage Systems for Motor Vehicle     |
|                              | Fueling*.                             |
+------------------------------+---------------------------------------+
| American Society of          | ASME, *Code for Unfired Pressure      |
| Mechanical Engineers         | Vessels*, Section VIII, Division I.   |
+------------------------------+---------------------------------------+

*NOTE: This listing of standards is limited to the most cited standards
and documents. A complete listing of related standards can be found in
NFPA 30, Annex H, which contains a complete listing of informational
references related to the design, installation and operation of
flammable and combustible liquids handing systems, tanks, and
equipment.*

*07-002*

FAA Paper 21607