Every above-ground LPG storage tank in a Thai gas depot now needs a water spray cooling system meeting a specific density, orifice size and discharge pressure, certified by a licensed professional engineer and trip-tested every year for the Department of Energy Business. The compliance window for existing depots closed on 18 February 2026.
A note on the figures in this article. The values quoted below are those published in the notification and in NFPA 15, given for general orientation. They are not a design basis for any particular depot. The densities, flows, reserve volumes and pump duties that apply to your tanks must be calculated from as-built geometry and certified by a licensed professional engineer under clause 5.
The deadline has already passed
Existing licensed depots were given one year from the gazette date of 18 February 2025 to comply. That period expired on 18 February 2026. If your cooling system has not been recalculated, certified and trip-tested, the depot is operating outside the notification today, not at some future date.
What the regulation actually is
The rule is the Ministry of Energy notification on water spray piping above the surface of above-ground LPG storage and dispensing tanks, and sprinkler fire protection for covered LPG loading platforms in LPG depots, B.E. 2567.
It was signed on 18 December 2024 and published in the Royal Gazette (volume 142, special part 75 Ngor, pages 10 to 13) on 18 February 2025, taking effect on publication. It is issued under clause 22(4) and clause 38 paragraph two of the Ministerial Regulation on LPG Depots B.E. 2564, which is why the two documents have to be read together: the parent regulation carries the water reserve and fire pump duties, and the notification carries the spray design criteria.
The notification covers two separate systems. Part 2 governs water spray cooling over above-ground LPG tanks. Part 3 governs sprinkler protection for covered LPG loading platforms. Most depots need both.
Does it apply to your tanks?
Yes, for any above-ground LPG storage or dispensing tank in a licensed gas depot, with one route out.
Clause 3 exempts tanks protected by fireproofing rated at least one hour thirty minutes to UL 1709, ASTM E119, ASTM E1529 or ISO 22899. If you hold a valid fireproofing certification to one of those standards, the notification does not apply to that tank. In practice most Thai depots do not, and the water spray route is the realistic one.
The technical requirements, clause by clause
The figures below are as published. Confirm them against the gazette text, and against the edition of NFPA 15 in force for your project, before using them in a specification.
Clause 7(1) — water density
At least 10.2 litres per minute per square metre of the tank’s outer surface area, with any fraction of a square metre rounded up. This is identical to NFPA 15 section 7.4.2.1 (0.25 gpm per square foot).
Clause 7(2) — nozzle spacing
Horizontal and vertical spacing must cover the entire tank surface. NFPA 15 allows a maximum rundown spacing of 3.7 m, and gives no rundown credit below the equator of a sphere, so the lower hemisphere needs dedicated rings.
Clause 7(3) — orifice and pressure
Nozzle orifice at least 6 mm, and pressure at least 20 psi (137.9 kPa) at the nozzle. This matches the NFPA 15 section 8.1.2 outdoor minimum and rules out several small-orifice nozzle models that are otherwise attractive because they keep pipe sizes down.
Clause 7(4) — pipework
Steel pipe with external corrosion protection, or stainless steel. Dry systems that are normally empty must be protected inside as well as outside. Galvanised deluge pipework corrodes internally, and this is a common finding on older installations.
Clause 7(5) — pump duration
The fire pump must run continuously for at least 30 minutes at the required flow and pressure from the depot’s water source. This is often the binding constraint.
Clause 5 — engineering certification
Calculations must follow the Engineering Institute of Thailand fire protection standard, and the system must be designed and supervised by a licensed professional engineer. Certification is part of compliance, not paperwork added afterwards.
Clause 8 — testing
An acceptance test on installation, then an annual functional test. Records must be kept for at least one year and made available to the DOEB. Testers must be qualified under the Section 7 ministerial regulation on testers and inspectors.
An indicative example: one 16.6 m sphere
The following illustrates the order of magnitude involved for a sphere of 16.6 m outside diameter. It is an illustration rather than a design calculation, and the rounded values should not be carried into a real project without an engineer rerunning them from as-built geometry.
- Surface area — pi times D squared, giving approximately 865 square metres.
- Spray demand — 865 multiplied by 10.2 L/min per square metre, giving approximately 8,850 litres per minute, or 531 cubic metres per hour.
- Statutory water reserve — 865 multiplied by 600 litres per square metre under clause 34 of the 2564 ministerial regulation, giving approximately 519 cubic metres, which is about 59 minutes of supply.
- Two-sphere scenario — two spheres at 8,850 L/min plus a hose allowance of 1,900 L/min, giving approximately 19,600 litres per minute, or 1,176 cubic metres per hour.
Note the last figure. NFPA 15 section 7.1.10.2 requires you to consider the burning tank together with adjacent exposed tanks. A depot that sized its pump and reserve for one sphere in isolation will fail a properly conducted review even if every individual spray ring is correct.
The two requirements depots most often miss
In our experience reviewing existing installations, the spray rings themselves are usually present. The failures are upstream.
Water reserve of 600 litres per square metre
Clause 34 of the 2564 ministerial regulation requires a permanent water source of at least 0.6 cubic metres for every square metre of tank outer surface, fractions rounded up. At the 10.2 L/min per square metre design density that is roughly 59 minutes of supply, so the legal floor is about one hour. International practice for LPG exposure fires under API 2510A is two hours or more. State both figures in any design report and let the operator make an informed decision.
An engine-driven fire pump
Clause 35 requires at least one engine-driven fire pump, sized to the EIT standard, able to reach every tank and every loading and receiving area, kept accessible and always ready, and tested at least once a year. Clause 36 additionally places pumps and fire equipment at least 30 m from loading platforms and tank groups. An electric-only pump set does not satisfy clause 35.
Testing and the DOEB record trail
Clause 8 creates an ongoing duty, not a one-time hurdle. You need an acceptance test when the system is installed or modified, then a functional test every year, both to the EIT standard. Records must be retained for at least one year and produced to the DOEB on request.
A defensible annual test covers spray coverage across the whole surface, pressure at the remotest nozzle of at least 1.4 bar, deluge valve trip time, and a pump run at rated duty. NFPA 15 section 10.4.2.1 expects the system to trip within 40 seconds of detection.
Covered loading platforms: the second half of the notification
Part 3 is easy to overlook because it sits behind the tank clauses, but it applies to any roofed LPG loading platform.
- Clause 10(1) — density of at least 12.2 L/min per square metre of platform area, fractions rounded up.
- Clause 10(2) — a maximum of 9.3 square metres protected per sprinkler.
- Clause 10(3) — sprinkler spacing no more than 3.7 m along a branch, and no more than 3.7 m between branches.
- Clause 10(4) — steel pipe with corrosion protection or stainless steel; dry systems protected inside and out.
- Clause 10(5) — pump running continuously for at least 30 minutes.
- Clause 11 — acceptance test plus annual test, with records kept at least one year for the DOEB.
If your depot is not compliant today
The deadline has passed, so the sequence matters. Work in this order.
- Recalculate the hydraulics from as-built geometry, not from the original design file, and have a licensed professional engineer certify the result.
- Run a witnessed full-flow test: confirm coverage over the whole surface, at least 1.4 bar at the remotest nozzle, and deluge trip within 40 seconds.
- Inspect pipework and nozzles for internal corrosion and plugging. Hot-dip galvanised deluge pipe ages badly on the inside, and blocked orifices are invisible until you flow the system.
- Confirm the water reserve reaches 600 litres per square metre, and that the engine-driven pump proves 30 minutes continuous at rated duty.
- Put the annual trip-test regime in place and start the DOEB record file.
Where a tank cannot practically be brought to the spray standard, the clause 3 fireproofing route remains open, but it requires a certified one hour thirty minute rating to one of the four named standards, which is a substantial specification in its own right.
Frequently asked questions
Does the rule apply to underground or mounded LPG tanks?
The notification addresses above-ground storage and dispensing tanks. Tanks that are genuinely mounded or underground fall outside Part 2, but the parent ministerial regulation still governs the depot’s water supply and fire pump provisions.
Can we use a smaller nozzle orifice if the hydraulics still work?
No. Clause 7(3) sets 6 mm as a floor independent of the hydraulic result. The reason is blockage: small orifices plug with scale and sediment, and a plugged nozzle is invisible until the system runs.
Is a hydraulic calculation on file enough to demonstrate compliance?
No. Clause 8 requires acceptance and annual functional testing with retained records. A calculation shows intent; a witnessed flow test shows the system actually delivers.
How long does a compliance upgrade usually take?
Recalculation and certification typically take a few weeks. Where nozzles, ring pipework or the pump set need replacing, the programme is driven by shutdown windows rather than by engineering time.
Related reading
- Safety & risk engineering services — assessment, design and compliance verification
- Hydrauvision fire pumps and water transport
- SATU engineering services
- Talk to SATU about an LPG cooling system review
This article summarises the regulation for general guidance only and is not engineering advice. All figures are indicative and subject to verification. Design, calculation and certification of a water spray system must be carried out by a licensed professional engineer under clause 5 of the notification, working from the current gazette text and the applicable edition of the referenced standards.
Image credits
Hero image: LPG storage spheres, Tarnów. Photo by Andrzej Otrębski, via Wikimedia Commons, licensed under CC BY-SA 4.0. Image resized and used with a dark overlay applied for display; the file itself is unmodified.
LPG sphere farm: photo by Manjarul.hasan, via Wikimedia Commons, licensed under CC BY-SA 4.0.