Recommended Product Specifications
Sub Base Fuel Tank
This specification describes requirements for a Sub Base Fuel Tank designed to support an
Emergency/Standby Power System (Diesel Generator Set). The codes and standards that are
referenced are typical for North American applications.
Note: Items in RED text should be adjusted to meet the appropriate specification. This
specification assumes that a number of pieces of information described on the mechanical and
electrical drawings provided for the project.
PART 1 - GENERAL
1.1 RELATED DOCUMENTS
A. Drawings and general provisions of the Contract, including General Conditions and Division 01
Specifications, apply to this Section.
1.2 SUMMARY
A. These specifications describe requirements for a fuel sub base tank sized to support full load
operation of a generator set for ____ hours.
B. The manufacturer shall design and furnish all materials and equipment to be fully compatible
with electrical environmental and space conditions of the site. It shall include all equipment to
safely support the full demands of the generator set and be designed for unattended operation.
1.3 DEFINITIONS – Select one (1) of the following UL / ULC listed classifications based on regional
requirements for the Project location.
A. Secondary Containment Generator Base Tank: Per UL 142 / ULC S601 Listing: Generator base
tank of a secondary-containment type. Constructed with two shells that form an interstitial space
capable of being pressurized and monitored for leakage.
B. Closed-top Diked Generator Base Tank: Per UL 142 / ULC S601 Listing: Generator base tank of
a diked containment type. Aboveground storage tank within a steel containment dike vessel
capable of being monitored for leakage, diked area is not capable of being pressurized. Dike is
covered to resist rain or debris entering the dike.
Sub Base Fuel Tank Specification
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1.4 CODES AND STANDARDS
1.4.1
The fuel sub base tank and all associated equipment and components shall be manufactured in
accordance with applicable listings for performance and safety.
A. UL 142 (US) Steel Aboveground Tanks for Flammable and Combustible Liquids
B. ULC S601 (CANADA) Steel Above Ground Tanks for Flammable and Combustible Liquids
1.4.2
The installing contractor shall be an experienced firm regularly engaged in the installation of sub
base fuel tanks, fuel piping systems and generator sets, and be responsible to conform to the
requirements of the codes and standards, as applicable.
The fuel sub base tank is intended for installation and use in accordance with the following
standards.
A. NFPA 30 – Flammable and Combustible Liquids Code
B. NFPA 37 – Standard For the Installation and Use of Stationary Combustion Engines and Gas
Turbines
C. NFPA 70 – National Electrical Code. Equipment shall be suitable for use in systems in
compliance to Article 700, 701, and 702.
D. NFPA 99 – Health Care Facilities Code
E. NFPA 110 – Standard for Emergency and Standby Power Systems
F. CSA B139-09 - Installation Code for Oil-burning Equipment
1.5 WARRANTY
A. Base Warranty: Manufacturer shall provide base warranty coverage on the material and
workmanship of the fuel sub base tank for a minimum of twelve (12) months from date of
shipment.
B. Extended Warranty: Manufacturer shall offer extended coverage of 2 to 5 years from date of
shipment.
PART 2 – PRODUCTS
2.1 MANUFACTURERS
A. Manufacturers: The basis for this specification is Tower Power Solutions fuel tank, approved
equals may be considered if equipment performance is shown to meet the requirements herein.
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2.2 CONSTRUCTION
A. Primary tank: Heavy gauge steel construction design uses structural baffles to preserve tank top
uniformity over the length of the tank. Primary tank shall have provisions for both normal and
emergency venting. The tank penetration openings for these vents shall be located on the top of the
tank.
a. Normal vent – A storage tank opening or device that automatically relieves internal pressure or
vacuum during normal storage (atmospheric pressure equalization) and during normal operations (fill
or withdraw). Normal vents are designed so as not to exceed 1.0 psig (6.9 kPa) pressure and minus
0.5 psig (minus 3.4 kPa) in the tank.
b. Emergency vent – A storage tank opening or device that automatically relieves excessive internal
pressure due to an external fire exposure or blockage of the normal vent. UL Listed emergency vent
cap shall be spring-pressure operated. Initial opening pressure shall be 0.5 psig; full opening pressure
shall be 2.5 psig.
B. The total (actual) capacity of primary tank shall not be: Less than the rated nominal capacity and
More than 105 percent of the rated nominal capacity
C. Secondary containment tank: The fuel sub base tank shall feature a welded steel containment
tank, sized at a minimum of 125% (Wisconsin/Chicago) of the tank capacity to prevent escape of fuel
into the environment in the event of a tank rupture.
D. The interstitial space of the secondary containment tank shall have provisions for emergency
venting. The tank penetration opening for this vent shall be located on the tank top, or near the top
provided the penetration opening is above the liquid level should the primary tank leak at rated
nominal capacity.
E. Secondary containment tanks shall be constructed to provide a means for monitoring leakage into
the interstitial (annular) space through the exterior of containment wall, design so that liquid can flow
freely within the interstitial space to the point of monitoring.
F. The tank requirements apply to steel primary, secondary and diked type atmospheric storage
tanks intended for noncorrosive, stable flammable and combustible liquids that have a specific gravity
not exceeding 1.0 for aboveground applications – ASTM D975 #2 Diesel Fuel
G. The UL / ULC listing mark shall be evidence that the tank has been fabricated, inspected and
tested for leakage before shipment from the factory as completely assembled vessel.
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2.3 FUEL TANK STANDARD FEATURES
A. The fuel tank shall include the following features:
a. Tank rails and lift lugs shall be rated for the full dry weight of the tank, genset, and
enclosure.
b. Electrical stub up(s) design dependent.
i. Full-width End with removable end plate
ii. Right-Hand, Left-Hand or both with removable end or side plate
iii. Internal Right-Hand, Left-Hand or both
c. Fuel fill port, lockable; 2” fuel fill.
i. 4” Fuel Fill
d. Mechanical fuel level gauge, UL Listed
e. Atmospheric vent cap, accommodates primary tank normal venting, raised above fuel fill
f. Emergency Pressure relief vent caps – UL Listed
g. Low Fuel Level Switch, to activate at 40% remaining fuel.
h. Leak detection switch, activates warning in the event of a primary tank leak within
containment basin (EQ listed)
i. Spare ports: Two above primary tank and one above containment basin for field upgrade
of regulation requirements or customer use.
2.4 TANK DESIGN AND FEATURES SHALL MEET THE REGIONAL REQUIREMENTS FOR
THE PROJECT LOCATION. – Select ALL that apply. REMOVE features that do not apply.
j. Tank extends beyond gen set base or enclosure periphery to accommodate external vents,
fuel fill and customer use fittings.
k. Normal Vent, located above containment tank
l. Spill box, 5 or 7.5 gallon ULC and Florida EQ Listed with integral drain to tank and
lockable lid.
i. Overfill Prevention, shuts off fuel flow during filling at approximately 95% of
tank full. Fuel fill down tube to terminate within 6 inches of bottom of fuel tank.
m. Fuel Fill Down Tube - terminates within 6” of bottom of tank. Not required when OFPV
is selected
n. High Fuel Switch to activate at 90% of fuel full level (EQ listed)
o. High Fuel Alarm Panel, audible and visual alarm of high fuel condition.
p. Critical Low Fuel Switch
q. Fuel gauge with sender, signal accepted by genset manufacturers control panel
r. Normal Vent Extension – Primary
s. Emergency Vent Extension, Primary and Containment basin.
t. Tank Risers, bolt-on allows visual inspection of tank to foundation clearance.
u. Warning Labels
i. NFPA 704 – Hazard Diamond
ii. Flammable – Keep Fire Away
iii. Combustible Liquids – Keep Fire Away
iv. No Smoking / No Open Flames
v. Tank Contents Label i.e.; Diesel, Bio-Diesel, etc.
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EXECUTION
3.1 INSTALLATION
A. Comply with packaged engine-generator manufacturers' written installation, application, and
alignment instructions and with NFPA 110.
B. Equipment shall be installed by the contractor in accordance with final submittals and contract
documents. Installation shall comply with applicable state and local codes as required by the
authority having jurisdiction. Install equipment in accordance with manufacturer's instructions
and instructions included in the listing or labeling of UL listed products
C. Installation of equipment shall include furnishing and installing all interconnecting wiring
between all major equipment provided for the on-site power system. The contractor shall also
perform interconnecting wiring between equipment sections (when required), under the
supervision of the equipment supplier.
D. Equipment shall be installed on concrete housekeeping pads. Equipment shall be permanently
fastened to the pad in accordance with manufacturer’s instructions and seismic requirements of
the site.
E. All equipment shall be physically inspected for damage. Scratches and other installation damage
shall be repaired prior to final system testing. Equipment shall be thoroughly cleaned to remove
all dirt and construction debris prior to initial operation and final testing of the system.
G. On completion of the installation by the electrical contractor, the generator set supplier shall
conduct a site evaluation to verify that the equipment is installed per manufacturer’s
recommended practice.
END OF SECTION
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