The storage and use of flammable gases shall be in accordance with this chapter. Compressed gases shall also comply with Chapter 30 and cryogenic fluids shall also comply with Chapter 32. Bulk hydrogen compressed gas systems and bulk liquefied hydrogen gas systems shall comply with NFPA 55. Hydrogen motor fuel-dispensing facilities and repair garages and their associated above-ground hydrogen storage systems shall also be designed and constructed in accordance with Chapter 22.
- Gases used as refrigerants in refrigeration systems (see Section 606).
- Liquefied petroleum gases and natural gases regulated by Chapter 38.
- Fuel-gas systems and appliances regulated under the International Fuel Gas Code other than gaseous hydrogen systems and appliances.
- Pyrophoric gases in accordance with Chapter 41.
The following words and terms shall, for the purposes of this chapter and as used elsewhere in this code, have the meanings shown herein.
BULK HYDROGEN COMPRESSED GAS SYSTEM. An assembly of equipment, consisting of, but not limited to, storage containers, pressure regulators, pressure relief devices, vaporizers, manifolds and piping, with a storage capacity of more than 400 ft3 (scf) (11 m3) of compressed hydrogen gas, including unconnected reserves integral to the system. The bulk system terminates at the point where the gas supply, at service pressure, first enters the supply line. The containers are either stationary or portable, and the gas is stored as a compressed gas.
BULK LIQUEFIED HYDROGEN GAS SYSTEM. An assembly of equipment, consisting of, but not limited to, storage containers, pressure regulators, pressure relief devices, vaporizers, manifolds and piping, with a storage capacity of more than 39.7 gallons (150 L) of liquefied hydrogen, including unconnected reserves integral to the system. The bulk system terminates at the point where the gas supply, at service pressure, first enters the supply line. The containers are either stationary or portable, and the gas is stored as a cryogenic fluid.
FLAMMABLE GAS. A material which is a gas at 68°F (20°C) or less at 14.7 pounds per square inch atmosphere (psia) (101 kPa) of pressure [a material that has a boiling point of 68°F (20°C) or less at 14.7 psia (101 kPa)] which:
- Is ignitable at 14.7 psia (101 kPa) when in a mixture of 13 percent or less by volume with air; or
- Has a flammable range at 14.7 psia (101 kPa) with air of at least 12 percent, regardless of the lower limit.
The limits specified shall be determined at 14.7 psi (101 kPa) of pressure and a temperature of 68°F (20°C) in accordance with ASTM E 681.
FLAMMABLE LIQUEFIED GAS. A liquefied compressed gas which, under a charged pressure, is partially liquid at a temperature of 68°F (20°C) and which is flammable.
METAL HYDRIDE. A generic name for compounds composed of metallic element(s) and hydrogen.
METAL HYDRIDE STORAGE SYSTEM. A closed system consisting of a group of components assembled as a package to contain metal-hydrogen compounds for which there exists an equilibrium condition where the hydrogen-absorbing metal alloy(s), hydrogen gas and the metal-hydrogen compound(s) coexist and where only hydrogen gas is released from the system in normal use.
- Cylinders of nonliquefied compressed gases not exceeding a capacity of 250 cubic feet (7.08 m3) or liquefied gases not exceeding a capacity of 40 pounds (18 kg) each at normal temperature and pressure (NTP) used for maintenance purposes, patient care or operation of equipment.
Containers of liquefied flammable gases and flammable gases in solution shall be positioned in the upright position or positioned so that the pressure relief valve is in direct contact with the vapor space of the container.
- Containers of flammable gases in solution with a capacity of 1.3 gallons (5 L) or less.
- Containers of flammable liquefied gases, with a capacity not exceeding 1.3 gallons (5 L), designed to preclude the discharge of liquid from safety relief devices.
|MAXIMUM AMOUNT PER STORAGE AREA (cubic feet)||MINIMUM DISTANCE BETWEEN STORAGE AREAS (feet)||MINIMUM DISTANCE TO LOT LINES OF PROPERTY THAT CAN BE BUILT UPON (feet)a||MINIMUM DISTANCE TO PUBLIC STREETS, PUBLIC ALLEYS OR PUBLIC WAYS (feet)a||MINIMUM DISTANCE TO BUILDINGS ON THE SAME PROPERTY|
|Nonrated construction or openings
within 25 feet
|2-hour construction and no openings within 25 feet||4-hour construction and no openings within 25 feet|
|0 - 4,225||5||5||5||5||0||0|
|4,226 - 21,125||10||10||10||10||5||0|
|21,126 - 50,700||10||15||15||20||5||0|
|50,701 - 84,500||10||20||20||20||5||0|
|84,501 or greater||20||25||25||20||5||0|
For SI: 1 foot = 304.8 mm, 1 cubic foot = 0.02832 m3.
- The minimum required distances shall not apply when fire barriers without openings or penetrations having a minimum fire-resistance rating of 2 hours interrupt the line of sight between the storage and the exposure. The configuration of the fire barrier shall be designed to allow natural ventilation to prevent the accumulation of hazardous gas concentrations.
Storage tanks shall be located outside in accordance with the following:
- Tanks and associated equipment shall be located with respect to foundations and supports of other structures such that the loads carried by the latter cannot be transmitted to the tank.
- The distance from any part of the tank to the nearest wall of a basement, pit, cellar or lot line shall not be less than 3 feet (914 mm).
- A minimum distance of 1 foot (305 mm), shell to shell, shall be maintained between underground tanks.
The tank shall be buried such that the top of the vacuum jacket is covered with a minimum of 1 foot (305 mm) of earth and with concrete a minimum of 4 inches (102 mm) thick placed over the earthen cover. The concrete shall extend a minimum of 1 foot (305 mm) horizontally beyond the footprint of the tank in all directions. Underground tanks shall be set on firm foundations constructed in accordance with the International Building Code and surrounded with at least 6 inches (152 mm) of noncorrosive inert material, such as sand.
Metal hydride storage systems shall be marked with the following.
- Manufacturer's name;
- Service life indicating the last date the system can be used;
- A unique code or serial number specific to the unit;
- System name or product code that identifies the system by the type of chemistry used in the system;
- Emergency contact name, telephone number or other contact information; and
- Limitations on refilling of containers to include rated charging pressure and capacity.
Metal hydride storage system valves shall be marked with the following:
- Manufacturer's name;
- Service life indicating the last date the valve can be used; and
- Metal hydride service in which the valve can be used, or a product code that is traceable to this information.
Metal hydride storage system pressure relief devices shall be marked with the following:
- Manufacturer's name;
- Metal hydride service in which the device can be used, or a product code that is traceable to this information; and
- Activation parameters to include temperature, pressure or both.
Cylinders, containers and tanks used in metal hydride storage systems shall be marked with the following:
- Manufacturer's name;
- Design specification to which the vessel was manufactured;
- Authorized body approving the design and initial inspection and test of the vessel;
- Manufacturer's original test date;
- Unique serial number for the vessel;
- Service life identifying the last date the vessel can be used; and
- System name or product code that identifies the system by the type of chemistry used in the system.