S-8 - Tanks.  


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  • S-8.1   Storage Tanks.

    S-8.1.1   Plans.

    Plans for storage tanks shall be submitted to the Authority Having Jurisdiction for approval, unless listed by an approved listing agency. Such plans shall show dimensions, reinforcing, structural calculations, and such other pertinent data as required by the Authority Having Jurisdiction.

    (Ord. 2013-0050 § 22, 2013.)

    S-8.1.2   Atmospheric Tanks.

    Atmospheric storage tanks shall be vented to the atmosphere and installed in accordance with the manufacturer's installation instructions.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.1.2.1   Overflow.

    Gravity tanks shall be installed with an overflow opening of not less than 2 inches (50 mm) in diameter. The openings shall be above ground and installed with a screened return bend.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.2.2   Makeup Water.

    Makeup water from a potable water system to an atmospheric tank shall be protected by an air gap.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.2.3   Draining.

    An overflow shall be provided for an atmospheric tank. The overflow shall be provided with a means of drainage in accordance with Section 303.0 of this Code. The overflow for an atmospheric tank containing nonpotable water shall be emptied into an approved container.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.3   Prefabricated Storage Tanks.

    Prefabricated storage tanks shall be listed by an approved agency and labeled.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.1.4   Pressure Vessels.

    A pressure-type storage tank exceeding an operating pressure of 15 psi (103kPa) shall be constructed in accordance with ASME BPVC Section VIII. Fiber-reinforced plastic storage tanks shall be constructed in accordance with ASME BPVC Section X.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.5   Devices.

    Devices attached to or within a tank shall be accessible for repair and replacement.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.5.1   Safety Devices.

    Pressure-type thermal storage tanks shall be installed with a listed combination temperature and pressure relief valve in accordance with Section S-13.3.1. The temperature setting shall not exceed 210°F (99°C) and the pressure setting shall not exceed 150 percent of the maximum designed operating pressure of the system, or 150 percent of the established normal operating pressure of the piping materials, or the labeled maximum operating pressure of a pressure-type storage tank, whichever is less. The pressure and temperature setting shall not exceed the pressure and temperature rating of the tank or as recommended by the tank manufacturer.

    Storage tanks and bottom-fed tanks connected to a water heater shall be designed to withstand vacuum induced pressure, or shall be provided with a vacuum relief in accordance with Section S-13.3.4. The vacuum relief valve shall be installed at the top of the tank and shall have an operating pressure not to exceed 200 psi (1379 kPa) and a temperature rating not to exceed 250°F (121°C). The size of such vacuum relief valves shall have a minimum rated capacity for the equipment served. This Section shall not apply to pressurized captive air diaphragm or bladder tanks.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.6   Separate Storage Tanks.

    For installations with separate storage tanks, a pressure relief valve and temperature relief valve or combination thereof shall be installed on both the main storage and auxiliary tank.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.1.6.1   Isolation Valves.

    Storage tanks shall be provided with isolation valves for servicing.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.7   Underground Storage Tanks.

    Tanks shall be permitted to be buried underground where designed and constructed for such installation.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.1.8   Tank Covers.

    Tank covers shall be structurally designed to withstand anticipated loads and pressures in accordance with the manufacturer's instructions.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.1.9   Drainage Pan.

    Where a water heater, boiler, or thermal storage tank is located in an attic, or in or on an attic-ceiling assembly, floor-ceiling assembly, or floor-subfloor assembly where damage may result from a leaking water heater, boiler, or tank, a watertight pan of corrosion-resistant materials shall be installed beneath the water heater, boiler, or tank, with not less than ¾ of an inch (20 mm) diameter drain to an approved location. Such pan shall be not less than 1 ½ inches (38 mm) in depth.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.10   Storage Tank Construction and Materials.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.10.1   Construction.

    Storage tanks shall be constructed of durable materials not subject to excessive corrosion or decay and shall be watertight. Each such tank shall be structurally designed to withstand anticipated loads and pressures and shall be installed level and on a solid bed.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.10.2   Concrete.

    The walls and floor of each poured-in-place, concrete tank shall be monolithic. The exterior walls shall be double-formed so as to provide exposure of the exterior walls during the required water test. The compressive strength of a concrete tank wall, top and covers, or floor shall be not less than 2500 psi (lb/in ) (1.7577 E+06 kg/m ). Where required by the Authority Having Jurisdiction, the concrete shall be sulfate resistant (Type V Portland Cement).

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.10.3   Metal Tanks.

    Metal tanks shall be welded, riveted and caulked, brazed, bolted, or constructed by use of a combination of these methods.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.1.10.4   Filler Metal.

    Filler metal used in brazing shall be nonferrous metal or an alloy having a melting point above 1000°F (538°C) and below that of the metal joined.

    (Ord. 2016-0055 § 20, 2016.)

    S-8.2   Expansion Tanks.

    S-8.2.1   Where Required.

    An expansion tank shall be installed in a solar thermal system as a means for controlling increased pressure caused by thermal expansion. Expansion tanks shall be of the closed or open type and securely fastened to the structure. Tanks shall be rated for the pressure of the system. Supports shall be capable of carrying twice the weight of the tank filled with water without placing strain on the connecting piping.

    Solar thermal systems incorporating hot water tanks or fluid relief columns shall be installed to prevent freezing under normal operating conditions.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.2.2   Solar Thermal Systems with Open-Type Expansion Tanks.

    Open-type expansion tanks shall be located not less than 3 feet (914 mm) above the highest point of the system. Such tanks shall be sized based on the capacity of the system. An overflow with a diameter of not less than one-half the size of the water supply or not less than 1 inch (25 mm) in diameter shall be installed at the top of the expansion tank. The overflow shall discharge through an air gap into the drainage system.

    (Ord. 2013-0050 § 22, 2013.)

    S-8.2.3   Closed-Type Solar Thermal Systems.

    Closed-type solar thermal systems shall have an airtight tank or other approved air cushion that will be consistent with the volume and capacity of the system, and shall be designed for a hydrostatic test pressure of two and one-half times the allowable working pressure of the system. Expansion tanks for systems designed to operate at or above 30 psi (207 kPa) shall comply with ASME BPVC Section VIII. Provisions shall be made for draining the tank without emptying the system.

    (Ord. 2016-0055 § 20, 2016: Ord. 2013-0050 § 22, 2013.)

    S-8.2.4   Minimum Capacity of Closed-Type Expansion Tank.

    The minimum capacity of a gravity-type hot water system expansion tank shall be in accordance with Table S-8.2.4(1). The minimum capacity for a forced-type hot water system expansion tank shall be in accordance with Table S-8.2.4(2) or Equation S-8.2.4.

    T28_S_8.2.4.png (Equation S-8.2.4)

     

    Where:

    Vt = Minimum volume of expansion tank, gallons.

    Vs = Volume of system, not including expansion tank, gallons.

    t = Average operating temperature, °F.

    Pa = Atmospheric pressure, feet H 2 O absolute.

    Pf = Fill pressure, feet H 2 O absolute.

    Po = Maximum operating pressure, feet H 2 O absolute.

    For SI units: 1 gallon = 3.785 L, °C = (°F-32)/1.8, 1 foot of water = 2.989 kPa

    (Ord. 2016-0055 § 20, 2016; Ord. 2013-0050 § 22, 2013.)

    TABLE S-8.2.4(1)
    EXPANSION TANK CAPACITIES FOR GRAVITY HOT WATER SYSTEMS

    INSTALLED EXPANSION DIRECT RADIATION* (square feet) TANK CAPACITY (gallons)
    Up to 350 18
    Up to 450 21
    Up to 650 24
    Up to 900 30
    Up to 1100 35
    Up to 1400 40
    Up to 1600 2 to 30
    Up to 1800 2 to 30
    Up to 2000 2 to 35
    Up to 2400 2 to 40

     

    For SI units: 1 gallon = 3.785 L, 1 square foot = 0.0929 m2

    *For systems exceeding 2400 square feet (222.9 m2) of installed equivalent direct water radiation, the required capacity of the cushion tank shall be increased on the basis of 1 gallon (3.785 L) tank capacity per 33 square feet (3.1 m2) of additional equivalent direct radiation.

    (Ord. 2013-0050 § 22, 2013.)

    TABLE S-8.2.4(2)
    EXPANSION TANK CAPACITIES FOR FORCED HOT WATER SYSTEMS

    SYSTEM VOLUME* TANK CAPACITY (gallons)
    100 15
    200 30
    300 45
    400 60
    500 75
    1000 150
    2000 300

     

    For SI units: 1 gallon = 3.785 L

    *Includes volume of water in boiler, radiation, and piping, not including expansion tank.

(Ord. 2013-0050 § 22, 2013.)