What you need to know about the new maintenance facilities Code for natural gas vehicle (NGV) and other alternative fueled vehicles

That is why the Énergir DATECH group has been working in close collaboration for several years with technical experts involved with the Canadian Standards Association (CSA Group) to develop codes especially for the alternative fuels market.

Recently, several codes have been revised and improved and are now available for building mechanical designers. These include the installation code for natural gas vehicles CSA-B109, the installation code for compressed natural gas (CNG) and liquefied natural gas (LNG) refueling stations CSA B108:21 series, and the second edition of the code on service establishments for natural gas vehicles CSA B401, which we will examine in detail in this article.

An indispensable Code for building mechanical designers

In 2016, the CSA Group set up a technical committee to develop a code expressly for the maintenance of natural gas vehicles. Their work led to the release of Code CSA-B401, the second edition of which was published in spring 2021. This code is aimed at establishing reasonable means to manage the risks associated with the maintenance and repair of CNG or LNG fueled vehicles in service establishments for motorized vehicles.

Principal changes in the second edition:

• clarification of intent of first edition;
• addition of Appendix D for private enclosed parking infrastructures;
• addition of Appendix E, as a comment, to provide additional information on the reasoning behind certain clauses in the Code;
• addition of coverage to address maintenance facilities for propane vehicles. This led the creation of separate codes to address different fuel types: CSA B401.1 for natural gas and CSA B401.2 for propane.

The CSA Group is already considering the possibility of additional chapters in its next edition covering maintenance facilities for hybrid and hydrogen vehicles.

More precise, more detailed

In addition, the Code contains non-exhaustive appendices on the procedures for operations and maintenance, safety training and intervention in emergencies for NGV maintenance facilities. Also, references to Code CSA B401 should be included in the next edition of the National Building Code of Canada (endorsed most of the time by Québec in its Construction Code), as well as in the National Fire Code of Canada.

Updated standards

Code CSA B401 also proposes improved air supply management compared with the rule of four fresh air changes per hour proposed in the temporary guides created a dozen years ago. Those guides aimed at compensating for the shortcomings in the design of maintenance facilities following the sudden appearance of LNG and CNG fueled trucks. The Code also includes details about the fresh air changes per hour needed for some types of repairs, whether minor or major. These details also consider the energy intensity (pressure) in vehicle tanks at the time of their repair.

A repair facility ventilated 24/24 to prevent possible fuel leaks would not be very energy efficient, so much so that the continuous rate of four changes of fresh air per hour is not justified.

Minor and major repairs

The Code establishes a risk-management strategy related to the pressure remaining in the tank that is equivalent to a manageable quantity of gas in case of an accidental spill. The Code therefore defines two types of repairs based on the risk of working near a vehicle’s fuel supply system: minor repairs and major repairs. A distinction is also brought to the risk of relying on the quantity of energy present during the repair. In fact, according to Code CSA B401, a mechanic or dealer may carry out “major” repairs on a CNG vehicle in an area designated for “minor” repairs, if the vehicle is depressurized beforehand in a secure outdoor location, under 500 psig (3,500 kPa). Note that the maximum operating pressure of a CNG vehicle tank is 3,600 psig (24,800 kPa), but the engine supply pressure is about 125 psig (860 kPa).

Distinct spaces

The repair areas of a facility can thus be designed and dedicated based on the risks involved. Several special features apply to adapting these spaces – in particular, the space for major work – but the principal points to be taken into account are the ventilation rate for fresh air and the installation of methane detectors. The following mechanical design tables indicate the electrical classification in the repair areas, as well as the entry authorizations for CNG vehicles (Refer to Code CSA B401 for the complete rules).

Two types of installation

The following graphics are based on these standards and they illustrate in part the requirements applicable to a facility or part of a facility used as an area for minor repairs.

1. Schematic overview for minor facility type area upgrade

Electrical unclassified areas for CNG vehicle under repair (CSA B401):

•  No required modification IF a continuous ventilating purge of 2 ACH is already provided

2. Schematic overview for minor facility type area upgrade – with modifications compared to the preceding situation

If the preceding situation is not applied, electrical unclassified areas for CNG:

•  Everywhere in the building for minor repairs if:
  • A continuous ACH of ½ is applied (generally the case – could be passive if the air is extracted 0.5 m from roof)
  • A gas detection system triggers on demand an exhaust system of 2 ACH