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

December 10, 2021   |    6 min.

It seems more and more clear that alternative fuels, such as natural gas, electricity (batteries) and hydrogen will be unavoidable in the future of trucking. The industry therefore needs to prepare for taking care of these new vehicles – some have already begun to do so, notably dealers and garages that do their maintenance.

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).

Electrical classification areas – Minor repair facility

Type of bay or area Classification Design requirements
Minor CNG repair area Unclassified All areas if a continuous ventilating purge of 2 air changes per hour (ACH) is provided
Unclassified All areas if:
  1. Continuous normal ventilation is applied of ½ ACH (may be passive or dynamic if the air is extracted 0.5 m from the roof)
  2. A gas detection system triggers on demand an exhaust system of 2 ACH
Class 1, area 2, Groupe IIA Areas immediately below the roof with a height of 0.5 m; 4.5 m in all directions from a ventilation purge vent if:
  1. No continuous ventilation of ½ ACH is provided and
  2. A gas detection system triggers on demand an exhaust system of 2 ACH

All the other areas are unclassified

Electrical classification areas – Major repair facility

Type of bay or area Classification Design requirements
Major CNG repair area Unclassified All areas if continuous ventilation is provided, as specified in the table on the right
Unclassified All areas if:
  1. Continuous normal ventilation is applied of ½ ACH (may be passive or dynamic if the air is extracted 0.5 m from the roof)
  2. A gas detection system triggers on demand an exhaust system, as specified in the table on the right
Class 1, area 2, Groupe IIA Areas immediately below the ceiling with a height of 0.5 m; 4.5 m in all directions from a ventilation purge vent if:
  1. No continuous ventilation of ½ ACH is provided and
  2. A gas detection system triggers on demand an exhaust system, as specified in the table on the right

All other areas are unclassified

 

Minimum ACH (changes of air per hour) for major work Volume of the major repair area “V ” (m3)
10.0 V<400
8.5 400<=V<800
7.0 800<=V<1,600
6.0 1,600<=V<3,200
5.0 3,200<=V<6,400
4.5 6,400<=V<12,800
4.0 V>=12,800

Authorizations of entry for CNG vehicles

Vehicle status – Pressure in tank system Type of repair Repair space needed
All pressure below or equal to 3600 psig (P/T compensated) Minor repair; or unsupervised storage during a minor repair Minor repair (and also major by default)
<500 psig Minor or major repair; or unsupervised storage during a minor or major repair Minor repair
>500 psig Major repair orunsupervised storage during a major repair Major repair

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
installation, minor work, ventilation

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
installation, minor work, ventilation

Adapted installations

It is also possible to design repair bays specifically for alternative fuels inside a facility that takes care of diesel vehicles. Gas-tight partitions made of a fire-resistant material will need to be added, and the new bays will need to be maintained at a sightly negative pressure through natural ventilation.

As for the requirement to depressurize the vehicle tank before doing major work in a repair area designed for minor work, the designers must ensure that the natural gas can be removed in a way that is safe and acceptable for the environment. The capture and flare by a catalytic system or the reinjection of gas at a small refueling station could be good solutions in this regard.

Taking an active part in decarbonization

While this article is only an overview of the new standards on the maintenance of natural gas and other alternative fueled vehicles, it is essential to recall that Québec’s decarbonization objectives will have a major impact on the transportation industry, which alone is responsible for more than 40% of GHG emissions. Alternative fuels are therefore expected to occupy a more and more important place in the trucking sector. In this context, building mechanical contractors and engineers will have a key role to play in adapting maintenance facilities so they comply with new standards in order to welcome this new generation of vehicles.

 

Sébastien Lajoie, Eng., CEM, CMVP
Technical Advisor CNG/LNG Technologies
DATECH Group

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