• If applicable

Posted Tuesday, September 28th, 2021


When you’re designing a building or commercial complex where a critical power backup solution is required, you’ll need to include a stand-by generator (genset) and a fuel source to ensure power is maintained for the specified number of hours should the power go out. For critical situations such as data centers, healthcare facilities and large commercial buildings, the most viable backup power source is currently diesel-powered generators. Although other solutions are being researched, diesel is still the simplest to specify, install and manage for all parties involved in the foreseeable future. With a genset, it is very likely you will be required to safely store the fuel supply in a building.

Emergency and stand-by diesel generator units are relied on at many more sites, including coal and nuclear power plants, as well as industrial, commercial, medical and educational facilities. This means that almost anywhere power is generated, you’ll find diesel is stored. And it needs to be stored correctly and safely.

For Australia and other projects across the Asia Pacific, we recommend you go through the AS1940:2017 Australian Standard as that will answer most questions (this can be purchased from https://infostore.saiglobal.com/). The AS1940:20217 standard is recognised across all Australia states, as well as many other Pacific Island nations. It’s written specifically for ‘The Storage and Handling of Flammable and Combustible Liquids’. For New Zealand projects, the relevant standard is called Health & Safety At Work  Hazardous Substances Regulations 2017. This is available free of charge from www.legislation.govt.nz. The objective of each standard is to promote the safety of persons and prevent damage to property and the environment where flammable or combustible liquids are stored or handled. In simple terms, this standard tells us how to correctly store fuel in a building.

However, to make your compliance process and journey through the project simple, in this article we will highlight the areas you need to focus on. We’ll be recommending varying solutions, some of which may not be the right fit for you project. But in any case, it is our mission to make your job simple, no matter what fuel storage method you end up specifying.

In this article we go over the three different options you have when it comes to safely storing fuel in a building, helping you specify a compliant solution for your project of client.

Tank Location

Clause 5.6 of the AS1940 Standard mentioned above relates to the ‘Location and Capacity of Indoor Tanks’. You’ll also find that 5.6.2 outlines three ways or positions within a building where you can place your tank (the relevant section in the NZ Health & Safety At Work (Hazardous Substances) Regulations is 17.63 Stationary tank for certain class 3.1C and 3.1D substances). See below some helpful hints we offer on each option:

  1. A double walled tank below the lowest floor level, installed in accordance with clause 5.12. This is an underground tank of which people in the industry call ‘dig a hole and bury it’.
  2. A single walled tank placed in a tank chamber or a sand-filled chamber, in accordance with clause 5.13. This is commonly referred to as a single wall tank in a fire-rated room. (See NZ Health & Safety At Work (Hazardous Substances) Regulations 17.63 (4) (a) and (7)).
  3. A tank having integral secondary containment with an FRL of 240/240/240 and complying with clause 5.9. This is commonly referred to as a ‘Fire-rated tank’ and is fast becoming the simplest way to comply. (See NZ Health & Safety At Work (Hazardous Substances) Regulations regulations 17.64 (6) (a)).

Here’s a brief comment on these three options:


– Burying your tanks underground – go to clause 5.12 in AS1940:2017 (See Health & Safety At Work (Hazardous Substances) Regulations 17.84, 17.85 and 17.86)

While this can be an excellent way of saving space in a tight location, it does come with some implications that need to be considered, eg. Overall cost, a more complex installation process, and the possibility of hidden services.  All these can cause delays during the construction process. The completed solution will need an ongoing monitoring program and may be difficult to inspect and repair. Leaks aren’t easily visible, and overall, the underground solution is a big expense with no ability to relocate or remove at ‘end-of-life’.

The cost associated with installing underground tanks can be higher than those for setting up an above ground tank and may require expensive excavation work, including a variety of permits, land use consents and specialising equipment for the installation. If burying a tank within a building, other factors you need to consider include access pits for servicing, proximity to property boundaries and building foundations and corrosion protection.


– Tanks located in a fire-rated room – Go to clause 5.13 in AS1940:2017 (See Health & Safety At Work (Hazardous Substances) Regulations 17.63 (4)(a) and (7)).

This method is not as difficult as underground. In the construction phase, you will need to consider that the walls, roof, and all penetrations in/out of the room will need to have an FRL (Fire Resistant Level) of 240/240/240. Fire-rated ventilation/dampers will also need to be installed. You will need to design a removable roof tank placement and a fire-rated door that is designed to stay closed. There are specific separation distances from other tanks that need to be kept to, along with services, foundations of the building and boundaries or other properties to be considered in keeping a safe distance from. In addition, the whole room will require water-tight bunding to be able to contain the volume of the largest tank in it.

It’s important to ensure that the concrete products used to construct the room have certification to the FRL (although commonly referred to as fire-rating, the correct term to describe the fire resistance of a building element is FRL – Fire Resistant Level). The FRL is the ability of a building element to withstand a fire under test conditions for a certain period and consists of the three criteria being structural adequacy, structural integrity, and insulation. This means that if a building element was exposed to a standard fire test, it would not be expected to fail for 240 minutes (4 hours) in each of the three following criteria:

  • Structural Adequacy: For a period of 240 minutes (4 hours) the product being tested was able to support a load while subject to fire conditions.
  • Integrity: The product did not disintegrate or crack so as to see flames of the fire for gases to escape.
  • Insulation: The product being tested did not transfer an average temperature reading that exceeds 180ºC above the ambient temperature.

In effect, this comes with most of the difficulties of the underground tank, and is potentially more expensive to install.


– Using a fire-rated tank with FRL of 240/240/240 – Go to clause 5.9.4 of AS1940:2017 (See Health & Safety At Work (Hazardous Substances) Regulations 17.63 (6)(a)).

Specifying a 4-hour fire-rated tank is fast becoming the simplest way to store fuel in a building. Although it takes up space where the underground tank does not, comments have been that the overall flexibility, cost and time savings make it worthwhile. These few notes will explain clause 5.9.4 of the AS1940 Standard where it discusses this option of storing fuel in a building.

While AS1940 defines fire  resistant level (FRL) in terms of AS1530.4 and this standard applies specifically to building construction, clause 1.2.24 clearly requires each of structural adequacy, integrity, and insulation to be demonstrated on the complete tank. Where the complete tank is subject to a recognised US standard test (NZ Health & Safety At Work (Hazardous Substances) Regulations require SwRI 95-03 – see interpretations page 41), only a 4-hour fire rating would be deemed equivalent to an FRL of 240/240/240. An example of an appropriate test is the 4-hour liquid hydrocarbon pool fire test to an appropriate SwRI (Southwest Research Institute) compliance.

Accordingly, a 4-hour fire-rated tank that complies with AS-1940 in regard to the SwRI-93-01 & 95-03 Standards is permitted by clause 5.9.2(a) and (b) are, by virtue of clause 5.9.4(c); “regarding as complying with the requirements for tanks in chambers (see clause 5.13.1 and 5.13.2)”. In less complicated terms, this means that the 4-hour fire-rated tank may store flammable or combustible liquids inside a building.

So in summary...

We think it’s a sensible decision and one with a lot less implications to make your choice the 4-hour fire-rated tank that complies with SwRI 93-01 & 95-03 standards and therefore meeting all compliance requirements. We are now in an age where the community is much more aware of the potential risks of pollution and flooding, and we have very strict regulations covering fuel storage and the consequences and penalties for any neglect can be huge.

Best engineering practice and design of fuel storage tanks has continued to develop to a point where above ground storage tanks offer 100% integrity. This has been achieved mainly by the introduction of the fire-rated tanks with advanced leak detection and online contents monitoring.

The Fuelchief team and our suppliers and manufacturers work very closely to provide the very best solution for your application.

Introducing the Supervault

If you're storing fuel in a building, this tank will tick all your boxes.