Ariz. Admin. Code § R13-13-201 – Minimum Standards for Compressed Natural Gas Fuel Systems

A. In addition to the definitions in R13-13-101, in this Article, unless otherwise specified:
“AGA” means the American Gas Association.
“ANSI” means the American National Standards Institute.
“Angle of departure” means the area above an imaginary line that extends from the bottom outside edge of the rear bumper on a vehicle to the point at which a tire on the vehicle’s rear drive axle touches the ground.
“Appurtenance” means an item connected to an opening of a natural-gas pressure vessel to make the natural-gas pressure vessel gas-tight. This includes pressure relief devices, shutoff, backflow, excess-flow, and internal valves, liquid-level and pressure gauges, and plugs.
“Approved” means acceptable to the Department.
“ASE” means National Institute of Automotive Service Excellence.
“Bracket” means rubber-lined, hoop and cradle mounting hardware supplied or approved by a pressure-vessel manufacturer to hold a natural-gas pressure vessel in a rack.
“CNG” means compressed natural gas, a combustible mixture of hydro-carbon gases and vapors, principally methane, that is reduced in volume by pressure for use as a vehicular fuel.
“Fuel-distribution assembly” means a device that regulates the flow of fuel from a natural-gas pressure vessel to a vehicle engine.
“Fuel line” means a pipe, tubing, or hose, and all related fittings through which natural gas passes on a vehicle.
“Installer” means a person who converts a school bus from the use of gasoline to the use of CNG by attaching a natural-gas fuel system to the school bus after the school bus is manufactured.
“Listed” means included in a publication of an approved organization that is concerned with product evaluation, conducts periodic inspection of equipment or material, and includes equipment or material in the approved organization’s publication only if the equipment or material complies with appropriate standards or performs in a specified manner.
“NFPA” means the National Fire Protection Association, which is located at 1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101, and which is accessible at (617) 770-3000 and www.nfpa.org.
“NGV-1” means specific standards set by the American National Standards Institute and American Gas Association for the refueling connection device of a natural-gas vehicle.
“NGV-2” means specific standards set by the American National Standards Institute and American Gas Association for a vehicle-on-board natural-gas pressure vessel.
“Natural gas” means a combustible mixture of hydrocarbon gases and vapors, principally methane.
“Natural-gas fuel system” means a group of items including a pressure vessel and all attached valves, piping, and appurtenances that form a network for distributing natural gas to a vehicle engine.
“Operating pressure” means the internal force that a manufacturer intends for a natural-gas pressure vessel to achieve during normal operation of the vehicle to which the natural-gas pressure vessel is attached.
“Out-of-service” means not compliant with these rules, NFPA 52, or manufacturer’s instructions for installation, maintenance, or repair.
“Owner” means a private business, school, or school district that owns a school bus.
“PSI” means pound per square inch.
“Pressure-relief device” means a mechanism that is installed in a natural-gas pressure vessel or integrated with a valve, that is operated by temperature, pressure, or both, and that releases the CNG in the natural-gas pressure vessel in specific emergency conditions. A pressure-relief device for a U.S. Department of Transportation or Canada Transport natural-gas pressure vessel also includes a mechanism capable of protecting a partially charged natural-gas pressure vessel.
“Pressure vessel” means a cylinder that is part of a natural-gas fuel system and that is constructed, inspected, and maintained in accordance with U.S. Department of Transportation or Canada Transport regulations or ANSI/AGA NGV2, Basic Requirements for Compressed Natural Gas Vehicle (CNGV) Fuel Containers, or CSA B51, Boiler, Pressure Vessel and Pressure Piping Code.
“Pressure-vessel valve” means a mechanical device connected directly to a natural-gas pressure vessel opening that regulates the flow of CNG from the natural-gas pressure vessel to the vehicle engine.
“Rack” means a metal structure that surrounds a natural-gas pressure vessel mounted on a vehicle and is secured to the vehicle frame by a method capable of withstanding a static up, down, left, right, forward, or backward force of eight times the weight of the fully pressurized natural-gas pressure vessel.
“UL” means the Underwriters’ Laboratory, Inc.
B. Applicability and enforcement date of this Section
1. 1. This Section applies to school buses that are manufactured to use only gasoline or diesel fuel and are converted to use CNG, in whole or in part.
2. 2. The Department shall enforce this Section beginning 180 days after it is filed with the Office of the Secretary of State. After the beginning enforcement date, a school bus that is manufactured to use only gasoline or diesel fuel and is converted to use CNG, in whole or in part, shall meet the requirements of this Section when the school bus is introduced into Arizona or when the school bus is converted to natural-gas power. A school bus introduced into Arizona and powered in whole or in part by CNG before the beginning enforcement date of this Section shall meet the requirements of this Section or those at A.A.C. R17-4-611.
3. 3. After the beginning enforcement date of this Section, the Department shall not approve a school bus manufactured to use only gasoline or diesel fuel and converted to use CNG, in whole or in part, unless the natural-gas fuel system meets the requirements of this Section.
C. Insurance
1. 1. An owner shall not contract with an installer unless the installer has insurance coverage provided by a comprehensive general liability broad form insurance policy that is approved by the Department. The insurance policy shall include coverage for liability resulting from:
  1. a. Completed installation operations,
  2. b. Harm that arises on the installer’s premises, and
  3. c. Breach of contract by the installer.
2. 2. In addition to the liability coverage described in subsection (C)(1), an owner shall ensure that either:
  1. a. The installer has insurance coverage for liability resulting from harm that arises from subcontracted work performed by an independent contractor, or
  2. b. An independent contractor who performs work for the installer under an agreement has an insurance policy that provides coverage for liability resulting from harm caused by the independent contractor’s work.
3. 3. An owner shall not contract with an installer unless the installer has an insurance policy that provides at least $1 million liability coverage per occurrence both for bodily injury and for property damage.
4. 4. An owner shall not contract with an installer unless the issuer of the installer’s insurance policies described in subsections (C)(1) through (C)(3) names the Department as an additional insured on each policy and keeps the Department informed of any change in the status of each policy.
5. 5. An owner shall obtain the Department’s approval of the installer’s insurance policy by submitting proof of the insurance described in subsections (C)(1) through (C)(3) to the Department before entering a contractual agreement with the installer for the installation of a natural-gas fuel system on a school bus.
6. 6. If an owner acts as an installer, the owner shall maintain the insurance required by this Section.
7. 7. The Department shall approve an installer’s insurance policy, proof of which is submitted by an owner in accordance with subsection (C)(5), if the policy conforms to the requirements in subsections (C)(1) through (C)(3). The Department shall send written notice of its decision to approve or disapprove the installer’s insurance policy to the owner within 15 days from receipt of the proof of insurance.
D. General requirements for installing a natural-gas fuel system
1. 1. Converting a school bus to use of CNG, whether in whole or in part, is not an alteration as defined in R13-13-101.
2. 2. Unless specifically provided otherwise in this Section, when installing a natural-gas fuel system, an installer shall use parts and equipment and perform work in a manner that meets or exceeds the standards of NFPA 52, Standard for Compressed Natural Gas (CNG) Vehicular Fuel Systems, 1995 (and no later editions or amendments), Quincy, MA, which is incorporated by this reference and on file with the Department and the Office of the Secretary of State.
3. 3. An installer shall use only UL-listed or AGA-approved carburetor equipment when installing a natural-gas fuel system on a school bus.
4. 4. An installer shall meet or exceed the recommended guidelines provided by the manufacturers of all parts of a natural-gas fuel system when installing the natural-gas fuel system on a school bus.
5. 5. An installer shall ensure that installation of a natural-gas fuel system on a school bus is performed by an individual who has proof of training provided by the manufacturer of the natural-gas fuel system or ASE alternative fuels certification.
6. 6. If a school bus is converted from the use of gasoline or diesel fuel to the dedicated use of CNG, the installer shall remove the gasoline or diesel-fuel tank and accompanying gasoline or diesel-fuel system parts from the school bus.
E. Natural-gas pressure vessel: An installer shall use only a natural-gas pressure vessel that is certified by its manufacturer as meeting or exceeding the NGV2 standards and as being U.S. Department of Transportation or ANSI listed. An installer shall use the natural-gas pressure vessel manufacturer’s recommended bracket.
F. Installing a natural-gas pressure vessel
1. 1. An installer shall securely attach a rack to the frame of a school bus in the following manner:
  1. a. By drilling no holes in the school bus frame that exceed the manufacturer’s requirements; and
  2. b. By using no welding on and applying no heat to the school bus frame.
2. 2. When installing a natural-gas fuel system on a school bus, an installer shall locate the natural-gas pressure vessel and its appurtenances on the vehicle frame as follows:
  1. a. Below the driver’s or passengers’ compartment;
  2. b. So no part protrudes:
    1. i. In front of the front axle,
    2. ii. Beyond the outside face of the rear bumper, or
    3. iii. Beyond the sides of the school bus;
  3. c. Inside a rack; and
  4. d. So the minimum clearance between the road and the lowest part of the natural-gas pressure vessel and its rack on a school bus loaded to its gross vehicle weight rating, is:
    1. i. No fewer than 7 inches (17.5 mm) for a school bus with a wheel base fewer than or equal to 127 inches (323 mm); or
    2. ii. No fewer than 9 inches (22.5 mm) for a school bus with a wheel base greater than 127 inches (323 mm).
3. 3. If the natural-gas pressure vessel and its appurtenances are located behind the rear axle of the school bus, in addition to the requirements in subsection (F)(3), an installer shall locate the natural-gas pressure vessel as follows:
  1. a. Below the floor line, and
  2. b. Above the school bus’ angle of departure.
G. Protecting a natural-gas pressure vessel. To protect a natural-gas pressure vessel and its appurtenances from damage, an installer shall:
1. 1. Surround the natural-gas pressure vessel with a stone guard on all sides that are not protected by the natural barriers of the vehicle. The stone guard shall not be attached to the natural-gas pressure vessel. If the stone guard protects a valve, it shall be made of at least 16-gauge steel. If the stone guard does not protect a valve, it shall be made of at least 3/16-in. mesh with openings no greater than 1 in.;
2. 2. Place a resilient, non-absorbent gasket between the natural-gas pressure vessel and its brackets in a manner that prevents the brackets from directly contacting the natural-gas pressure vessel;
3. 3. Ensure that the weight of the natural-gas pressure vessel is not supported, in whole or in part, by an appurtenance; and
4. 4. Place a shield between, but not attached to, the natural-gas pressure vessel and the vehicle exhaust system if the natural-gas pressure vessel or the fuel lines are located fewer than 8 inches from the exhaust system. The shield shall be constructed of at least 18-gauge metal.
H. Safety and check valves: An installer shall equip a natural-gas fuel system with:
1. 1. Either an automatic fuel supply shut-off valve that is placed between the pressure vessel fuel-pressure regulator and the fuel distribution assembly and activated by engine vacuum or oil pressure, or an electronic fuel injector; and
2. 2. Either a manual or automatically controlled shut-off valve that enables the natural-gas pressure vessel to be isolated from the remainder of the natural-gas fuel system. If a manual shut-off valve is used, it shall:
  1. a. Have no more than 90° rotation from the opened to the closed position;
  2. b. Have a red valve handle;
  3. c. Be placed in an accessible location; and
  4. d. Have “ESV” printed on the school bus at the access location to the manual shut-off valve, in 2-in. to 4-in., unshaded, red letters.
I. Installation of fuel lines. An installer shall:
1. 1. Use fuel lines constructed of seamless stainless steel that has been tested and certified by the manufacturer to an operating pressure of 3600 PSI with a 4:1 safety factor;
2. 2. Mount and brace fuel lines to the vehicle frame in a manner that minimizes vibration;
3. 3. Secure fuel lines to the vehicle frame at least every 24 inches with rubber-lined fasteners;
4. 4. Protect fuel lines that pass through any structural member with rubber grommets, bulkhead fittings, or both;
5. 5. Cause fuel lines that run to the engine to follow the main frame channel; and
6. 6. Install an access door that is at least 70 square inches if access to the fill receptacle and fuel pressure gauge is through the school bus body. The words “CNG Fill” shall be printed on the school bus body, immediately above the access door, in 2-in. to 4-in., unshaded letters.
J. Installation of Venting System. An installer shall ensure that in addition to meeting the requirements in NFPA 52, all vent exits are aimed toward the ground.

Historical Note

New Section adopted by final rulemaking at 6 A.A.R. 4115, effective October 3, 2000 (Supp. 00-4). New Section R13-13-201 recodified from R17-9-201 with Section cross-references revised, at 20 A.A.R. 2083, effective July 25, 2014 (Supp. 14-3).