NFPA 11 (2024 edition), the Standard for Low-, Medium-, and High-Expansion Foam, is the de-facto reference standard for foam systems at refineries, terminals and tank farms across Thailand. It is cited in EPC specifications, in insurance underwriting, and in the audit checklists used by major Thai oil refineries, petrochemical operators, tank-farm operators and national oil and gas companies. Yet many systems originally designed to NFPA 11 drift out of compliance not at the design stage, but during years of incremental operational change, foam supplier swaps and partial retrofits.
This guide focuses on the practical compliance checks an EHS or asset-integrity manager can run on an existing foam proportioning system, and explains where FireDos GEN III water-driven proportioners simplify both design and long-term ITM under NFPA 25 (2023 edition). For the parallel PFAS-transition story driving most current retrofits, see our IMO 2026 PFOS foam-ban guide for Thai operators.
SATU’s compliance principle: Every foam concentrate — existing or new — must be tested for proportioning-rate accuracy against the installed proportioner before the system can be signed off as NFPA 11 / NFPA 25 compliant. This guide does not recommend a specific brand; it explains what the audit trail must show.
Five NFPA 11 requirements that drive proportioner selection
1. Proportioning accuracy
NFPA 11 requires the proportioning rate to remain within the design band, typically 3% +0.3 / -0 percentage points for a 3% concentrate. Older balanced-pressure and bladder-tank systems struggle to hold this band across the full flow range, especially when only a few monitors or chambers are activated. FireDos GEN III water-driven proportioners hold the rate across an FM Approved 1:15 turndown (for example 1,330 l/min to 20,000 l/min on the FD20000/3-S) because the ratio is mechanically locked to the firewater flow.
2. Foam concentrate compatibility
NFPA 11 requires the proportioner, concentrate and discharge device to be qualified together. Swapping a foam concentrate without re-checking the proportioner is one of the most common findings on Thai sites. The FireDos GEN III FD2000, FD6000, FD10000 and FD20000 range covers AR-AFFF, AR-SFFF, FFF, Class A and PFAS-free concentrates. Concentrate options being evaluated on Thai sites include the BIOEX ECOPOL family (ECOPOL Premium for marine and tank-farm AR service, ECOPOL F3HC for hydrocarbon-only bunds) and the VERSAGARD family by Perimeter Solutions (VERSAGARD AS-100 3×3 where UL 162 plus IMO MSC.1/Circ.1312 are required by the underwriter). The choice depends on the binding listing stack at the site — and any concentrate must be tested for proportioning-rate accuracy against the proportioner before commissioning, regardless of family.
3. Listing and approvals
NFPA 11 expects the system to be listed by an approved testing laboratory. UL Listed and FM Approved are the credentials Thai underwriters and EPC reviewers look for. FireDos GEN III is FM Approved, with VdS approval on the FD10000/3-S, and the M-series monitors (M1, M2, M4 and M9) are qualified for hydrocarbon and polar-solvent service.
4. Discharge device coverage and design density
The application rate at the discharge device must meet NFPA 11 minimums. For Class IB and IC hydrocarbons in fixed-roof storage tanks, the standard sets a minimum application rate of 4.1 L/min/m² (0.10 gpm/ft²) at the foam-water solution, with discharge times typically 55 minutes for crude oil and Class I liquids and 30 minutes for Class II and III. For carbon steel external floating-roof tanks and full-contact internal floating roofs, NFPA 11 requires a higher minimum rate of 12.2 L/min/m² over the rim seal area for at least 20 minutes. A proportioner that loses accuracy at low flow will starve the rim seal during the early phase of a fire.
5. Reliability of energy source
NFPA 11 requires the system to operate on the energy available during a fire. Bladder-tank systems depend on the firewater pressure differential. Balanced-pressure systems depend on a foam pump and its driver. Water-driven proportioning uses only the firewater itself. Fewer single points of failure means a shorter compliance argument.
Where Thai facilities fail NFPA 11 audit
Across the Sriracha refinery cluster, the Map Ta Phut petrochemical zone, the Laem Chabang and Songkhla port complexes, and upstream onshore facilities operated by major Thai oil refineries, petrochemical operators and tank-farm operators, four findings recur:
- Proportioning rate drift after a foam swap. The new concentrate is more viscous, the seal package was not changed, and the rate has drifted to 2.4% on a 3% design.
- Annual ITM run with water only. NFPA 25 allows water-only flow tests for many components, but the proportioning rate itself must be verified. Sites that have not run a rate test in three or more years are flagged.
- Inadequate documentation of design density. When a tank is repurposed or the rim seal is replaced, the application rate is rarely re-derived against the 4.1 or 12.2 L/min/m² thresholds.
- Mixed concentrate stocks. Trailers and portables holding a different concentrate to the fixed system. NFPA 11 expects compatibility within the response strategy.
Building a defensible compliance file
A compliance file should let an auditor walk from the hazard, to the design rate, to the proportioner, to the concentrate, to the most recent ITM result, in five steps.
Hazard and design rate
Document the protected hazard, application method, design density in L/min/m², and the assumed fire size and duration. Reference the NFPA 11 (2024) clause for each number.
Proportioner specification
Capture the model, listing certificates, design flow envelope, design proportioning rate, and seal package. For FireDos GEN III systems this is a single sheet with the FD model number (FD2000/FD6000/FD10000/FD20000), UL and FM listings, and the concentrate type.
Concentrate certification
Hold the supplier’s batch certificate, the listing for the concentrate against the hazard class, and the PFAS declaration. For PFAS-free systems the file should reference the specific listing — for example EN 1568-3 Class 1A for BIOEX ECOPOL F3HC, or UL 162 plus IMO MSC.1/Circ.1312 for VERSAGARD AS-100 3×3 — matched to the concentrate that has been tested with the installed proportioner.
ITM record
Hold the most recent NFPA 25 ITM record, including the measured proportioning rate. SATU’s NFPA-aligned ITM service uses FireDos eco-friendly testing that verifies the rate without discharging foam concentrate, which protects sites near the Gulf and the Andaman.
Training record
Crew training, especially after a concentrate or proportioner change. Auditors increasingly ask for evidence the response crew has trained on the current concentrate’s expansion behaviour.
Choosing a proportioner for a Thai retrofit
For brownfield retrofits, the FireDos GEN III FD1000 to FD20000 range covers most refinery and terminal envelopes. Three questions decide the scope:
- Does the existing skid have the footprint? Usually yes. The FireDos GEN III package is more compact than equivalent bladder-tank systems.
- Is there an electrical hazard envelope to simplify? Water-driven proportioning needs no electrical service to the proportioner itself, which simplifies ATEX-classified zones at jetties and bunding.
- What is the long-term concentrate strategy? If the site plans to migrate to a PFAS-free concentrate such as BIOEX ECOPOL Premium or VERSAGARD AS-100 3×3, the retrofit should be specified for that concentrate from day one and the proportioning rate verified during commissioning before declaring the system compliant.
When NFPA minimums are not enough — the M9 case for full-surface and bund fires
NFPA 11 design rates assume an early-stage rim-seal or process-area fire, but Thai operators must also plan for the worst-case scenario: a full-surface tank fire or a bund-area fire after a major release. In these scenarios the smaller M-series monitors (M1, M2, M4) cannot deliver the foam volume or reach required to control the perimeter. The FireDos M9 is the only M-series monitor rated for the worst-case full-surface and bund scenario.
- Design flow: 10,000 L/min at a minimum supply pressure of 7 bar, scalable across the wider M9 envelope (10,000 to 40,000 L/min) where the supply allows.
- Throw range: design throw at 30° elevation, sufficient to project foam across a typical bunded enclosure from a perimeter-mounted location.
- Mounting: 5 m mounting height for tank-rim and bund coverage. Available as both fixed monitor and trailer-mounted mobile unit, so a single platform supports planned tank protection and rapid mobile response.
- Application: full-surface fixed-roof tank fire, external floating-roof rim-seal escalation that has spread to full surface, bunded-area fire, jetty manifold incidents that exceed manual hand-line capacity.
For Thai operators sizing a defensible response, the M9 is the design point that puts the system above NFPA minimums for major-incident scenarios, not just routine compliance.
FAQ
Is NFPA 11 mandatory in Thailand?
NFPA 11 is not enacted as Thai national law, but it is referenced in the design specifications of most major Thai operators and in the underwriting requirements of industrial insurers. In practice, designing outside NFPA 11 (2024 edition) is rarely accepted on a refinery or terminal in Thailand.
How does NFPA 11 interact with NFPA 25?
NFPA 11 sets the design and acceptance requirements. NFPA 25 (2023 edition) sets the inspection, testing and maintenance requirements for the installed system. A facility needs both, and the audit file should make the connection visible.
Can FireDos eco-friendly testing satisfy NFPA 25?
Yes. The FireDos test method verifies the proportioning rate using a calibrated test medium without discharging firefighting foam to the environment. It is consistent with NFPA 25 and is well-suited to environmentally sensitive Thai sites such as port terminals and coastal facilities.
What is the realistic budget for a tank-farm proportioner retrofit?
For a single bunded area with one to two protected tanks, a FireDos GEN III retrofit including engineering, equipment, installation and commissioning typically falls in the low to mid seven-figure THB range. Multi-bund and jetty-manifold scopes scale from there.
Do I need to retrofit if my system was designed to NFPA 11 ten years ago?
Not automatically. Run the five-step compliance file above. If the proportioning rate, concentrate compatibility, listings, discharge density and energy source all still line up, the system is in scope. The most common reason to retrofit is a foam concentrate change, especially the PFAS transition.
Get your NFPA 11 compliance file in order
SATU Innovative is the FireDos service partner in Thailand. We support Thai refineries, tank farms and port facilities with NFPA 11 design reviews, FireDos GEN III retrofits, and NFPA 25 ITM that produces the documentation Class, Flag State and corporate auditors expect to see. To scope a compliance review or a retrofit on your facility, Request a Quote and we will respond within five working days.
External References
- NFPA 11 (2024 edition), Standard for Low-, Medium-, and High-Expansion Foam — nfpa.org/11
- NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems — nfpa.org/25
- FireDos GEN III stationary proportioners (FD1000 to FD20000) — firedos.com
- BIOEX ECOPOL F3HC product page — bio-ex.com
- VERSAGARD AS-100 3×3 by Perimeter Solutions — perimeter-solutions.com
Our Partners
SATU Innovative is the authorised Thailand service partner for the brands behind this guidance.
