The following words and terms shall, for the purposes of this chapter and as used elsewhere in this code, have the meanings shown herein.
GASEOUS HYDROGEN SYSTEM. An assembly of piping, devices and apparatus designed to generate, store, contain, distribute or transport a nontoxic, gaseous hydrogen containing mixture having at least 95-percent hydrogen gas by volume and not more than 1-percent oxygen by volume. Gaseous hydrogen systems consist of items such as compressed gas containers, reactors and appurtenances, including pressure regulators, pressure relief devices, manifolds, pumps, compressors and interconnecting piping and tubing and controls.
HYDROGEN CUTOFF ROOM. A room or space which is intended exclusively to house a gaseous hydrogen system.
HYDROGEN-GENERATING APPLIANCE. A self-contained package or factory-matched packages of integrated systems for generating gaseous hydrogen. Hydrogen-generating appliances utilize electrolysis, reformation, chemical or other processes to generate hydrogen.
Valves including shutoffs, check valves and other mechanical restrictions shall not be installed between the pressure relief device and container being protected by the relief device.
Exception: A locked-open shutoff valve on containers equipped with multiple pressure-relief device installations where the arrangement of the valves provides the full required flow through the minimum number of required relief devices at all times.
Pressure relief devices shall be arranged to discharge unobstructed in accordance with Section 2209 of the International Fire Code. Discharge shall be directed to the outdoors in such a manner as to prevent impingement of escaping gas on personnel, containers, equipment and adjacent structures and to prevent introduction of escaping gas into enclosed spaces. The discharge shall not terminate under eaves or canopies.
Exception: This section shall not apply to DOTn-specified containers with an internal volume of 2 cubic feet (0.057 m3) or less.
Hydrogen piping systems shall be marked in accordance with ANSI A13.1. Markings used for piping systems shall consist of the name of the contents and shall include a direction-of-flow arrow. Markings shall be provided at all of the following locations:
- At each valve.
- At wall, floor and ceiling penetrations.
- At each change of direction.
- At intervals not exceeding 20 feet (6096 mm).
Gauges used for testing shall be as follows:
- Tests requiring a pressure of 10 psig (68.95 kPa gauge) or less shall utilize a testing gauge having increments of 0.10 psi (0.6895 kPa) or less.
- Tests requiring a pressure greater than 10 psig (68.98 kPa gauge) but less than or equal to 100 psig (689.5 kPa gauge) shall utilize a testing gauge having increments of 1 psi (6.895 kPa) or less.
- Tests requiring a pressure greater than 100 psig (689.5 kPa gauge) shall utilize a testing gauge having increments of 2 psi (13.79 kPa) or less.
Exception: Measuring devices having an equivalent level of accuracy and resolution shall be permitted where specified by the design engineer and approved by the code official.
Gaseous hydrogen systems shall be located in indoor rooms or areas in accordance with one of the following:
- Inside a building in a hydrogen cutoff room designed and constructed in accordance with Section 421 of the International Building Code;
- Inside a building not in a hydrogen cutoff room where the gaseous hydrogen system is listed and labeled for indoor installation and installed in accordance with the manufacturer's installation instructions; and
- Inside a building in a dedicated hydrogen fuel dispensing area having an aggregate hydrogen delivery capacity not greater than 12 SCFM and designed and constructed in accordance with Section 703.1.