A foam fire suppression system is an active fire protection system that delivers firefighting foam — produced by mixing foam concentrate with water and aerating the solution — to suppress or extinguish flammable liquid and solid fuel fires. Foam systems range from simple portable equipment carried on a fire engine, to complex engineered fixed systems on petroleum storage tank farms, aircraft hangars and offshore platforms that operate automatically on fire detection.
This guide covers every element of foam fire suppression system design — the difference between fixed and portable systems, the five main proportioner types, how to select the correct foam concentrate for the hazard, key NFPA 11 design requirements, and how all the components connect into a complete, compliant system.
Contents
Fixed vs Portable Foam Fire Suppression Systems
All foam fire suppression systems fall into one of two broad categories — fixed systems that are permanently installed and protect a specific hazard area, and portable systems that are carried to the fire by firefighting crews. Many facilities use both: a fixed system provides immediate automatic protection when a fire is detected, while portable equipment allows firefighters to reinforce, mop up and protect adjacent areas.
Fixed Systems
Permanently Installed — Automatic or Manual Activation
Engineered and installed to protect a specific hazard — a storage tank, a pump room, an aircraft hangar. The concentrate storage, proportioner, pipework and nozzles are all permanently connected. The system can activate automatically on fire detection or manually by an operator.
✓Immediate response — no setup time
✓Can be automatic — operates unattended
✓Designed to NFPA 11 for the specific hazard
→Higher capital cost, requires maintenance programme
Portable Systems
Mobile — Deployed by Firefighting Crews
Portable foam equipment — foam tenders, CAFS rigs, lightweight foam units — is carried to the incident by firefighters. The crew sets up the proportioner, connects to a water supply, and applies foam through a portable branch pipe or monitor. CA-FIRE’s lightweight portable foam unit (轻便式) is designed for rapid deployment at fuel depots, chemical plants and loading terminals.
✓Flexible — can be used anywhere
✓Lower capital cost
✓Supplements fixed systems
→Requires trained crew; setup takes time
Fixed System Sub-Types
Core Components of a Foam Fire Suppression System
Regardless of system type or hazard, every foam fire suppression system consists of the same fundamental components. Each must be correctly specified, sized and interconnected for the system to perform to the design standard.
System Flow — From Concentrate to Foam
🛢️
Concentrate Storage
Bladder tank / drum / IBC
→
⚙️
Proportioner
Mixes conc. + water
→
💧
Foam Solution
Flows through pipework
→
🔫
Nozzle / Generator
Aspirates air into solution
→
🫧
Finished Foam
Applied to fire
1
Water Supply
A reliable, pressurised water supply capable of delivering the system design flow rate for the full operating duration. May be a mains supply, dedicated fire water ring main, storage tank with fire pumps, or sea water supply for marine installations. Water supply design must account for simultaneous demands from other fire protection systems on the same site.
2
Foam Concentrate Storage
The concentrate storage vessel — a bladder tank (pressure proportioner), a dedicated concentrate storage tank, or IBC totes — must hold sufficient concentrate for the full system operating duration per NFPA 11, plus any required reserve. The storage must be sized for the design mixing ratio and the maximum system flow rate. Labelling, temperature management and annual inspection are mandatory.
3
Proportioner (Foam Induction Device)
The proportioner meters the correct percentage of concentrate into the water supply to produce foam solution at the design ratio (3% or 6%). It must be calibrated for the specific concentrate type and maintain accurate ratio across the full flow range. See Section 3 for a full comparison of proportioner types.
4
Distribution Pipework & Valves
The fixed pipe network that carries foam solution from the proportioner to the nozzles or foam makers. Pipe sizing must ensure the design flow rate is maintained at the required pressure at the most remote nozzle. Isolation valves, drain valves and pressure gauges are installed at appropriate points for maintenance and testing.
5
Foam-Generating Nozzles / Equipment
The foam-making device — an aspirating nozzle, foam pourer, foam monitor, foam maker or high-expansion generator — that entrains air into the foam solution to produce finished foam at the required expansion ratio. Nozzle type determines expansion ratio, throw distance, application pattern and foam quality. Selection is dictated by the system type and hazard geometry.
6
Detection, Control & Alarm
For automatic fixed systems: fire detectors (heat, smoke or flame) trigger the control panel, which initiates the alarm sequence, opens the deluge valve or bladder tank discharge valve, and starts the foam pumps. Manual activation stations must also be provided at accessible locations outside the hazard zone. The alarm system must comply with NFPA 72.
Proportioner Types — Compared
The proportioner is the most critical component in any foam system — it determines how accurately concentrate is inducted into the water supply, and therefore whether the foam solution meets the specification required for the fire class and system design. CA-FIRE manufactures the PHYM pressure proportioner series (vertical and horizontal) alongside its foam concentrate range, covering flow rates of 4–120 L/s at 0.6–1.2 MPa working pressure.
CA-FIRE PHYM Bladder Tank Proportioner — Key Specifications
3% / 6%
Mixing Ratio
4–120 L/s
Flow Range
0.6–1.2 MPa
Working Pressure
Available in vertical (立式) and horizontal (卧式) configurations. Storage volumes from 0.5 m³ to 13 m³. Compatible with all CA-FIRE AFFF, AR-AFFF, FFFP, High Expansion and Synthetic concentrate types at 3% or 6% mixing ratio.
Foam Delivery Equipment
The foam delivery device — the item at the end of the system that converts foam solution into finished foam and directs it onto the fire — determines the expansion ratio achieved, the throw distance, the application pattern and whether the application is gentle enough to avoid disrupting the foam blanket.
🔫 Foam Branch Pipe
Handheld aspirating nozzle used by firefighters for direct foam application. Lightweight and portable, suitable for spill fires and supplementary attack. Produces low expansion foam at 6–9×.
Use with: AFFF, AR-AFFF, FFFP, Synthetic S-type
🎯 Foam Monitor (Cannon)
Fixed or oscillating high-flow foam cannon. Delivers foam over long distances at high flow rates. Used for large open-area hazards — tank farm perimeters, loading racks, helidecks. Fixed monitors operate automatically; mobile monitors are positioned by crews.
Use with: AFFF, AR-AFFF, FFFP
🪣 Foam Pourer / Foam Maker
Fixed device mounted on the shell wall of a storage tank, directing foam gently onto the fuel surface. The gentle application is essential — foam must flow over the fuel surface, not be driven into it. Used in surface application systems on cone-roof tanks.
Use with: AFFF, FFFP — gentle application critical
🌊 High-Expansion Generator
Blower-type device that forces large volumes of air through a foam-wetted mesh screen, producing 201–1000× foam. Must be used with dedicated high-expansion concentrate (YEG-3 / YEG-6). Cannot be used with low-expansion foam types.
Use with: High Expansion only — YEG-3 / YEG-6
💨 CAFS Nozzle
Compressed air is injected into the foam solution upstream of the hose, producing a dry, lightweight foam that clings to vertical surfaces and travels up to 20 m. Primarily used with Class A foam on wildland and structural fires.
Use with: Class A MJABP, Synthetic S-type
⬇️ Subsurface Injection Nozzle
Foam solution is injected through a base pipe into the bottom of a storage tank. Requires a high-back-pressure foam maker that resists fuel back-pressure as the foam rises. FFFP is the preferred concentrate for subsurface injection due to its oil-shedding properties.
Use with: FFFP preferred; AFFF limited effectiveness
Foam Concentrate Selection by Hazard
The concentrate type is determined by the fire hazard — the fuel type, the application method and the performance requirements of the applicable standard. The following table maps the most common foam system scenarios to the correct CA-FIRE concentrate:
→ Full concentrate comparison: Types of Foam Concentrate — all 6 types explained
NFPA 11 Design Requirements
NFPA 11: Standard for Low-, Medium-, and High-Expansion Foam is the primary international standard for foam fire suppression system design. It governs concentrate selection, application rates, proportioner accuracy, system pipework design, concentrate supply duration, testing and maintenance. Key chapters relevant to system designers:
Chapter 3 — Definitions
Precise definitions of foam concentrate, foam solution, foam, expansion ratio, mixing ratio, proportioner, application rate and design area. Essential reference for specification writing.
Chapter 4 — System Components
Requirements for proportioner accuracy (±20% of design ratio across full flow range), concentrate storage, pipework materials and foam-making equipment selection.
Chapter 5 — Low-Expansion System Design
Application rates by tank type and diameter, foam supply duration (minimum 20–30 min for storage tanks), design area calculations, and subsurface injection requirements for Class I and Class II flammable liquids.
Chapter 6 — High-Expansion System Design
Fill time requirements (2 min engine rooms, 4 min hangars), minimum foam depth (600 mm), ventilation shutdown, pre-discharge alarms, life safety and concentrate supply duration.
Annex B — Performance Test Methods
Expansion ratio, 25% drainage time, spread coefficient (AFFF/FFFP) and fire performance test methods used to qualify foam concentrates to the standard.
Annex C — In-Service Testing
Annual foam concentrate sampling, testing frequency, acceptance criteria and documentation requirements for systems already in service. Non-compliance = system not considered operational.
Note on GB 15308: In China, foam concentrate must comply with GB 15308 — 泡沫灭火剂, which specifies performance test methods and classification. Foam suppression system design additionally references GB 50151 (泡沫灭火系统技术标准). CA-FIRE foam concentrate is batch-tested to GB 15308 at our Fujian facility, with test certificates available for all orders.
Application Rates & Minimum Supply Durations
NFPA 11 specifies minimum foam solution application rates and minimum supply durations for different hazard types and tank configurations. These values are the basis for calculating the required concentrate volume for any fixed system.
Reference: NFPA 11 (2021 edition) — Tables 5.3, 5.7.3 and Chapter 6. Always verify against the current edition and local AHJ requirements. Values shown are indicative; actual design values depend on fuel type, tank diameter and local regulatory requirements.
System Type by Protected Hazard
🛢️
Petroleum Storage Tank Farm
Fixed surface foam pourer or monitor system with bladder tank proportioner (PHYM). AFFF for standard tanks; FFFP for large crude oil tanks. Subsurface injection with FFFP for sealed floating-roof tanks. Design to NFPA 11 Chapter 5 and API 2030.
✈️
Airport ARFF & Hangars
ARFF vehicles carry AFFF in around-the-pump or direct-injection proportioner systems for vehicle fuel spill fires. Aircraft hangars: foam-water deluge (AFFF) or high-expansion flooding (YEG-3/YEG-6) per NFPA 409. Design to ICAO Annex 14 for ARFF vehicles.
Concentrate: AFFF / High Expansion
🚢
Marine Vessels
Engine room and machinery space: high-expansion flooding system (SOLAS, 2-minute fill). Cargo deck foam: AFFF monitors or deluge for tanker decks. ARFF/sea water grade AR-AFFF for chemical tankers with polar solvent cargo. Design to SOLAS Chapter II-2.
🧪
Chemical & Pharmaceutical Plants
Fixed foam deluge or monitor systems on solvent storage tanks and bunds. AR-AFFF mandatory where polar solvents (ethanol, IPA, acetone, MEK) are stored or processed. Bladder tank proportioner with PHYM series provides reliable ratio control for AR-AFFF’s higher viscosity.
Concentrate: AR-AFFF
🌲
Wildland & Structural Firefighting
CAFS-equipped fire engines carry Class A foam concentrate for direct attack on wildland fires, structural fires and WUI structure defence. Class A foam at 0.1–1% with direct injection proportioner achieves 50–75% water saving. No fixed system — portable tactical deployment by crews.
Concentrate: Class A MJABP
🏭
General Industrial & Mixed Hazards
Fixed deluge or monitor systems on transformer bunds, industrial fuel storage, warehouses with flammable liquid storage and mixed-hazard manufacturing sites. Synthetic S-type covers both Class A and B from a single stock, simplifying system maintenance. Compatible with all standard proportioner types.
Concentrate: Synthetic S-Type
Testing & Maintenance Requirements
A foam fire suppression system that has not been tested and maintained is not a reliable system — regardless of how well it was originally designed and installed. NFPA 11 and NFPA 25 establish minimum inspection, testing and maintenance (ITM) requirements that must be followed to maintain system compliance.
→ Full storage and testing guide: Foam Concentrate Storage & Shelf Life — complete maintenance guide
Foam Fire Suppression System Design Checklist
Use this checklist as a starting framework when beginning a new foam suppression system design or reviewing an existing system specification:
📚 Standards & Technical References
→ NFPA 11: Standard for Low-, Medium-, and High-Expansion Foam — The primary design, installation and testing standard for all foam fire suppression systems worldwide.
→ NFPA 16: Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems — Covers foam-water sprinkler and deluge systems specifically.
→ NFPA 25: Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems — ITM requirements for foam-water systems and proportioners.
→ NFPA 409: Standard on Aircraft Hangars — Foam suppression system requirements for Group I and Group II aircraft hangars.
→ API 2030: Application of Fixed Water Spray Systems for Fire Protection in the Petroleum Industry — Foam system design for petroleum tank farms and loading terminals.
→ IMO SOLAS Chapter II-2 — Fixed fire suppression system requirements for merchant vessels, including engine room foam flooding and tanker deck foam systems.
Related Articles & Products
Need Foam Concentrate for Your Suppression System?
CA-FIRE manufactures all six foam concentrate types and PHYM bladder tank proportioners factory direct from Fujian. Tell us your system type, hazard, mixing ratio and required volume — we will confirm the correct concentrate and provide a project quote within one business day. SDS, TDS and GB 15308 test certificates with every order.