Industrial Fire Protection Systems: Sprinklers, Foam, Gas and Hydrants

Quick Answer

Fire protection system selection follows the hazard, and the hazard classification determines everything downstream. Under NFPA 13, occupancies run from Light Hazard (design density around 4.1 mm/min over 139 m²) through Ordinary Hazard Groups 1 and 2 (6.1-8.1 mm/min) to Extra Hazard Groups 1 and 2 (12.2-16.3 mm/min), with storage occupancies handled by separate criteria entirely. Water remains the default agent because it absorbs more heat per unit mass than any practical alternative — about 2,257 kJ/kg in latent heat of vaporisation alone. Foam is required for flammable liquid hazards, where water alone spreads the fire; AFFF, fluoroprotein and increasingly fluorine-free (F3) concentrates are proportioned at 1%, 3% or 6% depending on the product and the fuel, with polar solvents requiring alcohol-resistant types. Clean agent gaseous systems protect occupied electrical and electronic spaces: inert gases (IG-01, IG-55, IG-100, IG-541) work by oxygen reduction to around 12-14%, halocarbons (FK-5-1-12, HFC-227ea) mainly by heat absorption, both at concentrations below the no-observed-adverse-effect level. Fire pumps to NFPA 20 must deliver 150% of rated flow at a minimum 65% of rated pressure, with churn pressure not exceeding 140% of rated — and the pump must be sized against the single most demanding hydraulic area, not the whole system.

A warehouse in East Africa stored palletised packaged goods — cartons, plastic film, some aerosols — at 7.5 metres. It had a sprinkler system. The design density was 5 mm/min over 140 m², which is roughly Light Hazard criteria.

The fire started in the aerosol section. The sprinklers operated and did essentially nothing: the fire plume from a high-piled rack storage fire develops far more heat release than 5 mm/min can absorb, so the sprinklers opened across a large area, dropped the system pressure, and delivered a fraction of the required density to any of them. Forty-one heads were open when the water supply ran out.

The building was a total loss. The insurance assessment found the system had been designed to the wrong occupancy class from the outset — storage occupancies with that commodity class and that height needed roughly 12 mm/min with a much larger design area, in-rack sprinklers, or an ESFR system with a water supply several times larger.

A sprinkler system designed to the wrong hazard class is not partial protection. It is a system that proves it was installed, operates, and fails.

Hazard Classification — The Decision That Determines Everything

NFPA 13 classifies occupancies by the quantity and combustibility of contents and by the expected rate of heat release.

Storage occupancies are classified separately by commodity class (I through IV plus Group A, B and C plastics), storage arrangement (palletised, rack, solid pile, shelf), and storage height. A Class IV commodity or Group A plastic at height requires densities and water supplies far beyond any ordinary hazard figure, and frequently requires in-rack sprinklers or ESFR.

Design density and design area work together. Water supply demand is approximately density × area, plus hose stream allowance, held for the required duration — 30 to 60 minutes for light and ordinary hazard, 60 to 120 for extra hazard and storage. This product, not the density alone, sizes the pump and the tank.

Getting the classification wrong is the root cause of most inadequate systems. It must be established from the actual commodity, the actual storage arrangement and the actual height, and revisited whenever occupancy changes — which it does, constantly, without anyone telling the fire engineer.

Sprinkler Systems

Wet pipe

Pipework permanently filled with water. A sprinkler operates, water discharges immediately.

• Simplest, most reliable, fewest components, lowest cost
• Fastest response — no delay
• Cannot be used where freezing is possible, or where accidental discharge would be unacceptable
• The default system wherever conditions allow

Dry pipe

Pipework filled with pressurised air or nitrogen holding a dry pipe valve closed. A sprinkler operates, air pressure falls, the valve trips and water flows.

• For unheated spaces: loading docks, cold stores, unheated warehouses, car parks
• Delay of up to 60 seconds between sprinkler operation and water arrival, during which the fire grows
• NFPA 13 requires water delivery within 60 seconds for systems above a certain volume, which drives the use of accelerators and limits on system size
• More components, more maintenance, higher cost
• Internal corrosion is a known problem: air in a wet-walled pipe causes oxygen corrosion and pinhole leaks. Nitrogen inerting is now common practice and markedly extends system life.

Pre-action

A dry system where water entry requires both detection system actuation and sprinkler operation.

• Single interlock: detection opens the valve; water then waits at the heads until one opens
• Double interlock: both detection actuation and loss of air pressure are required before the valve opens — protects against accidental discharge from a damaged pipe
• Used where accidental water discharge would be catastrophic: data centres, museums, archives, clean rooms, freezer rooms
• Most complex, highest cost, requires detection system integration and regular functional testing

Deluge

All sprinklers are open — no thermal element. The system is dry until a detection system opens the deluge valve, at which point water discharges from every nozzle simultaneously.

• For high-hazard areas where fire spreads faster than individual heads could respond: transformer bays, flammable liquid loading racks, LPG spheres, process units, turbine lube oil systems, aircraft hangars
• Provides cooling of adjacent equipment and surface wetting, not just fire suppression
• Very high water demand, because the whole system discharges at once
• Detection design is critical — the system does nothing until detection operates, so detector type, placement and response time are part of the fire protection design, not an electrical afterthought

Sprinkler head types

• Standard response (5 mm glass bulb or fusible link) — RTI above 80, for storage and where pre-wetting of adjacent areas is desirable
• Quick response (3 mm bulb) — RTI 50 or below, operates faster, limits fire size, standard for light hazard and life safety
• Extended coverage — larger spacing per head, up to about 20 ft × 20 ft, fewer heads but higher flow each
• ESFR (Early Suppression Fast Response) — high K-factor (K-14 to K-28), high pressure, designed to suppress rather than control a storage fire without in-rack sprinklers. Needs significant pressure at the head — typically 2.4-5.2 bar — and has strict obstruction and ceiling-height rules.
• Residential — specific spray pattern for wall wetting in dwellings
• Sidewall — for corridors and rooms where ceiling pipework is impractical
• Dry pendent and dry sidewall — for freezer and unheated spaces served from a heated wet system

Temperature ratings: ordinary 57-77°C, intermediate 79-107°C, high 121-149°C, extra high 163-191°C. Heads must be rated above the maximum ambient at ceiling level — under a skylight, near a heater or in an uninsulated roof space in a hot climate, ordinary-rated heads nuisance-trip. Conversely, over-rating heads delays operation and allows the fire to grow.

K-factor defines discharge: Q = K√P, with Q in L/min and P in bar. Common values are K-80 (nominal 15 mm), K-115 (20 mm), K-160, K-200, K-240 and above. Higher K delivers more water at a given pressure, which is how ESFR achieves its density without extreme pressures.

Fire Pumps (NFPA 20)

The water supply is the system. A perfectly designed sprinkler layout on an inadequate supply protects nothing.

Performance requirements

NFPA 20 requires a fire pump to deliver:

• 100% of rated flow at 100% of rated pressure
• 150% of rated flow at not less than 65% of rated pressure
• Churn (no-flow) pressure not more than 140% of rated pressure

The 150% point matters because real fire demand often exceeds the nominal design point, and the 140% churn limit matters because excessive shut-off pressure overpressurises the system and its components.

Driver options

Electric motor — simple, reliable, needs a reliable power supply. NFPA 20 requires either a reliable utility source, a dedicated generator, or a second independent source. Fire pump controllers are listed assemblies with specific transfer, monitoring and alarm requirements, and are not ordinary motor starters.

Diesel engine — independent of the electrical supply, which is why it is specified where power reliability is doubtful. Requires a fuel tank sized for the required run duration (typically 8 hours of full-load operation under NFPA 20), engine cooling with a reliable water supply, batteries with dual chargers, a ventilated and heated pump house, and weekly test running. A diesel fire pump that is not exercised weekly is not a fire pump.

Steam turbine — rare, used where high-pressure steam is always available.

Configuration

Horizontal split case — the standard for most installations, flooded suction, easy to maintain.

Vertical in-line — compact footprint.

Vertical turbine — for suction lift from a well, tank or open water source where positive suction pressure is unavailable. The only option where the water level is below the pump.

End suction — smaller duties.

Jockey pump

A small pump maintaining system pressure so the main pump does not start on minor leakage. Sized to make up normal leakage only — typically 1-3 L/s — and set to start and stop above the main pump's start pressure so pressure is restored without calling the fire pump.

Essential ancillaries

• Flow test loop with a test header or flow meter, so annual full-flow testing can be done without discharging to waste
• Casing relief valve where churn pressure or temperature could damage the pump
• Circulation relief valve to prevent overheating at churn
• Suction and discharge gauges, and an eccentric reducer on suction with the flat side up to avoid air pockets
• OS&Y gate valve or listed butterfly valve, supervised open
• Suction pipe design — no elbow within 10 pipe diameters of the suction flange on split case pumps, straight approach, adequate submergence, and vortex suppression at the tank draw-off

Water supply

Tank capacity = (design density × design area + hose allowance) × duration. For an Ordinary Hazard Group 2 system at 8.1 mm/min over 139 m² plus 950 L/min hose allowance for 60-90 minutes, the stored volume typically lands in the region of 130-190 m³ before any margin.

Tanks are bolted steel panel, welded steel, concrete or GRP. The tank must be dedicated to fire protection, or have a dedicated reserve that process use cannot draw down — a shared tank with no partition between the process draw-off and the fire reserve has failed to be a fire water supply at the moment someone fills a tanker.

Foam Systems

Water alone on a flammable liquid fire spreads burning fuel. Foam forms a blanket that excludes oxygen, cools, and suppresses vapour release.

Concentrate types

The PFAS transition is a live design issue. Fluorine-free concentrates are not drop-in substitutes: they often require higher application rates, different discharge devices, and a thorough system flush because residual fluorinated concentrate contaminates the new fill. Any new system, and any refill of an existing one, should be designed against current regulation in the destination country and the owner's own policy, not against what the old system used.

Expansion ratios

• Low expansion (up to 20:1) — tank protection, bund and spill fires, loading racks, monitors, aircraft rescue
• Medium expansion (20:1 to 200:1) — bunds, spill containment, vapour suppression
• High expansion (200:1 to 1,000:1) — total flooding of enclosed spaces, warehouses, LNG spill vapour control, basements

Proportioning methods

• Inline balanced pressure — a foam pump and a balancing valve keep concentrate pressure matched to water pressure across the whole flow range. The most accurate and most flexible, used on large fixed installations.
• Bladder tank (pressure proportioning) — water pressure squeezes a bladder containing concentrate. No power required, which is a significant advantage; limited to one tank-full, and refilling takes the system out of service.
• In-line eductor (venturi) — simple and cheap, but accurate only over a narrow flow range and imposes a substantial pressure loss, typically one-third of inlet pressure.
• Around-the-pump proportioner — simple, but sensitive to discharge pressure variation.

Application devices

• Foam chambers / air foam makers on fixed-roof tanks, discharging gently onto the surface
• Rimseal pourers on floating roof tanks
• Subsurface injection through the tank shell, using fluoroprotein — the foam rises through the fuel. Avoids the exposure of a topside approach and is unaffected by a damaged roof.
• Monitors, fixed and oscillating, for bunds, loading racks and large area coverage
• Foam-water sprinklers and spray nozzles for loading racks, hangars and process areas
• High expansion generators for total flooding

NFPA 11 application rates

Indicative rates for hydrocarbon fuels:

• Fixed roof tank, fixed foam system: 4.1 L/min/m² of liquid surface, 55 minutes for hydrocarbons
• Floating roof rimseal: 12.2 L/min/m² of seal area, 20 minutes
• Monitor application to spill fires: 6.5 L/min/m²
• Loading rack and spill area with foam-water sprinklers: 6.5 L/min/m²
• Polar solvents require higher rates per the concentrate's own listing — the manufacturer's listed rate governs, not the generic figure

Gaseous and Clean Agent Systems

For spaces where water would destroy the protected asset: electrical rooms, control rooms, data centres, switchgear, archives, laboratories, machinery spaces.

Inert gas systems (NFPA 2001)

IG-01 (argon), IG-55 (argon/nitrogen 50:50), IG-100 (nitrogen), IG-541 (nitrogen 52%/argon 40%/CO₂ 8%).

• Extinguish by reducing oxygen from 21% to roughly 12-14%, below which most fires cannot sustain combustion but humans can still function for the time needed to evacuate
• No decomposition products, zero ozone depletion potential, zero global warming potential
• Stored as high-pressure gas at 200-300 bar — large cylinder banks and substantial floor space
• Discharge time 60-120 seconds
• Room overpressure during discharge is a real structural hazard — pressure relief venting must be calculated and installed, and rooms have been damaged by systems with inadequate venting

Halocarbon systems

FK-5-1-12 (fluoroketone, Novec 1230) and HFC-227ea (FM-200).

• Extinguish primarily by heat absorption, with some chemical action
• Design concentrations typically 4-6% for FK-5-1-12 and 6.25-9% for HFC-227ea, which must be below the NOAEL for occupied spaces
• Discharge in 10 seconds, so faster knockdown than inert gases
• Stored as liquid, so far less storage space than inert gas
• FK-5-1-12 has an atmospheric lifetime of days and GWP of about 1; HFC-227ea has a GWP around 3,350 and is subject to F-gas phase-down in many jurisdictions
• Decomposition produces hydrogen fluoride if the agent passes through flame, so fast detection and discharge matter

CO₂ systems

• Extinguish by oxygen displacement at design concentrations typically 34% and above
• Lethal at design concentration. Permitted only in normally unoccupied spaces, with pre-discharge alarms, time delays, lock-off devices and strict procedural controls. Fatalities from CO₂ system discharge are well documented.
• Still used for specific industrial applications: turbine enclosures, ovens, dip tanks, cable tunnels

Essential requirements for all gaseous systems

• Room integrity (door fan) testing to verify the enclosure holds the agent for the required retention period, typically 10 minutes. An otherwise perfect system in a leaky room discharges and the concentration falls below extinguishing level within a minute. Retest after any building work.
• Sealed cable and pipe penetrations, and dampers on ventilation that close on actuation
• Pressure relief venting sized by calculation
• Detection with cross-zoning to avoid false discharge
• Manual release and abort provisions where personnel may be present
• Interlocks to shut down ventilation and, where appropriate, power

Water Mist

Fine water droplets, typically below 200 microns, at low pressure (below 12.5 bar), intermediate, or high pressure (above 35 bar).

• Extinguishes by evaporative cooling and local oxygen displacement; the very high surface-area-to-volume ratio makes evaporation far more effective than from conventional sprinkler droplets
• Uses a fraction of the water of a sprinkler system, typically 10-20%, so far less water damage and much smaller tanks and pipework
• Effective on machinery space fires, turbine enclosures, cable tunnels, archives, historic buildings, and increasingly on data centre and electronics risks
• Performance is listing-specific and cannot be extrapolated. A system listed for a machinery space is not approved for a warehouse. Always design to the manufacturer's listing for the specific hazard and enclosure volume.
• Nozzles have very small orifices, so water quality and filtration are critical; stainless steel pipework is standard

Hydrants, Monitors and Hose Systems

Fire hydrant networks (NFPA 24 for private service mains, local codes for public) — buried ring mains with isolation valves so a single break does not disable the whole network. Pillar and underground hydrants, with spacing and flow per the applicable code and the hazard. Looped mains, not dead-end branches.

Fire water ring main sizing should consider the largest single demand plus hose streams, with velocity below about 3-4 m/s to limit surge and friction loss. Buried mains in corrosive soils need coating and cathodic protection; AWWA C105 polyethylene encasement is common for ductile iron.

Monitors — fixed, oscillating or remotely controlled, for tank farms, loading racks, jetties and process units. Water, foam or combined. Remote control is increasingly specified so operators are not required to approach the fire.

Hose reels and standpipes — for first aid firefighting and for fire brigade use. Standpipe classes under NFPA 14 distinguish occupant-use (Class II, 38 mm hose), fire department use (Class I, 65 mm outlets) and combined (Class III). Pressure limits at the outlet are specified and often require pressure-regulating devices in tall buildings.

Hydrant and monitor flow testing is the only way to know what the network actually delivers. Design calculations and as-built reality frequently differ, usually because of closed valves nobody knew about.

Detection and Alarm

Suppression without detection is only as good as the thermal element in a sprinkler head. Deluge, pre-action and gaseous systems depend entirely on detection.

• Heat detectors — fixed temperature and rate-of-rise. Slow but reliable, for dirty and dusty environments.
• Smoke detectors — ionisation and photoelectric. For occupied and electronics spaces. Prone to nuisance alarm in dusty or humid industrial areas.
• Aspirating smoke detection (ASD) — very early warning by continuously sampling air through a pipe network. The standard for data centres, switchrooms and high-value spaces.
• Linear heat detection cable — digital or analogue, for cable trays, conveyors, tunnels and tank rimseals.
• Optical flame detectors — UV, IR, UV/IR and triple IR. Fast response to flaming hydrocarbon fires, for process areas, loading racks and turbine enclosures. Must be selected against the specific fuel's emission spectrum and against expected false-alarm sources — sunlight, arc welding, hot surfaces.
• Gas detection — catalytic bead or infrared for flammable gas, electrochemical for toxic. Detects the release before it ignites, which is a different and often more valuable function.
• Fire alarm control panels — addressable, with cause-and-effect matrices defining what each detection zone actuates. The cause-and-effect matrix is a document that must be written, reviewed and functionally tested; most commissioning problems in fire detection are matrix errors rather than hardware faults.

Common Specification Mistakes

1. Wrong hazard classification. The East African warehouse: storage commodity and height requiring roughly 12 mm/min protected at 5 mm/min.

   Prevention: Establish the classification from the actual commodity, storage arrangement and height, document it, and reassess whenever occupancy changes.

2. Sizing the pump on the whole system rather than the most demanding hydraulic area. Either grossly oversized — wasting capital and risking overpressure — or, where the designer picked a convenient area rather than the worst one, undersized.

   Prevention: Perform hydraulic calculations for the most remote and most demanding design area and verify the pump curve against that demand plus hose allowance.

3. Shared fire water tank with no dedicated reserve. Process use draws the tank down and the fire reserve is not there when needed.

   Prevention: Specify a dedicated fire water tank, or a shared tank with the fire reserve physically protected by draw-off elevation or partition.

4. No room integrity test on a gaseous system. The agent discharges and leaks away within a minute.

   Prevention: Require door fan integrity testing at commissioning and after any building work, with sealed penetrations and ventilation dampers interlocked to actuation.

5. No pressure relief venting on a gaseous system. Discharge overpressure damages walls, ceilings and doors.

   Prevention: Calculate relief vent area for the agent, discharge rate and enclosure, and install before commissioning.

6. Sprinkler temperature rating not matched to ceiling ambient. Nuisance operation under skylights and near heat sources in hot climates, or delayed operation where heads are over-rated.

   Prevention: Determine maximum ceiling-level ambient including solar gain, and select head ratings accordingly, zone by zone.

7. Dry pipe system without corrosion management. Air in wet-walled pipe causes oxygen corrosion and pinhole leaks within a few years.

   Prevention: Specify nitrogen inerting, adequate drainage with auxiliary drains at all trapped sections, and pitch the pipework to the required slope.

8. AFFF system refilled with fluorine-free concentrate without system review. F3 foams often need different application rates, different devices and a full flush of residual fluorinated concentrate.

   Prevention: Treat an F3 conversion as a design change: confirm listings for the specific hazard, recalculate rates, review hardware, and specify the decontamination procedure.

9. Eductor proportioning selected for a system with wide flow variation. Proportioning accuracy collapses outside a narrow band.

   Prevention: Use inline balanced pressure proportioning where flow varies, and reserve eductors for fixed single-device applications.

10. Diesel fire pump installed and never exercised. Batteries flat, fuel degraded, engine will not start.

    Prevention: Specify weekly test running with recorded results, fuel polishing or scheduled replacement, dual battery chargers, and a pump house maintained within the specified temperature range.

11. Suction piping with an elbow immediately at the pump flange. Flow distortion causes vibration, cavitation and a pump that does not make its curve.

    Prevention: Provide at least 10 pipe diameters of straight suction pipe to a split case pump, with an eccentric reducer flat side up.

12. Cause-and-effect matrix not written or not tested. Detection operates and the wrong things happen, or nothing happens.

    Prevention: Require a written cause-and-effect matrix as a deliverable, reviewed by the owner, and functionally tested point by point at commissioning.

13. Water mist system specified by analogy rather than listing. A system listed for machinery spaces applied to a warehouse has no basis.

    Prevention: Match the manufacturer's listing to the specific hazard, enclosure volume and ceiling height, and require the listing documentation.

Supply from Kasko Makine

Kasko Demir Çelik Makine supplies fire protection equipment and the piping systems that carry it:

Sprinkler and water-based systems

• Sprinkler heads: standard and quick response, pendent, upright, sidewall, concealed, extended coverage, ESFR, dry pendent, in all temperature ratings and K-factors
• Alarm valves, dry pipe valves, pre-action valves, deluge valves and trim sets
• Water motor alarms, pressure switches, flow switches and supervisory switches
• Open spray nozzles, directional and medium-velocity water spray nozzles
• Water mist nozzles and high-pressure skids
• Grooved couplings, fittings, flange adapters and grooved valves
• Pipe hangers, supports, seismic bracing and sway bracing to NFPA 13
• Test and drain assemblies, inspector's test connections

Fire pumps and water supply

• Horizontal split case, vertical in-line, vertical turbine and end suction fire pumps to NFPA 20
• Electric motor and diesel engine drivers
• Listed fire pump controllers and automatic transfer switches
• Jockey pumps and pressure maintenance packages
• Flow test headers, flow meters, casing and circulation relief valves
• Bolted steel panel tanks, welded steel tanks and GRP tanks
• Suction assemblies, vortex inhibitors, foot valves and strainers

Foam systems

• AFFF, AR-AFFF, fluoroprotein, protein, fluorine-free and high-expansion concentrates
• Bladder tank proportioners, inline balanced pressure skids, eductors and around-the-pump proportioners
• Foam chambers, rimseal pourers, subsurface injection assemblies
• Foam-water sprinklers, foam nozzles and branch pipes
• Low, medium and high expansion generators
• Fixed, oscillating and remote-controlled monitors in water and foam duty

Gaseous and clean agent systems

• IG-01, IG-55, IG-100 and IG-541 inert gas systems with cylinder banks and manifolds
• FK-5-1-12 and HFC-227ea halocarbon systems
• CO₂ high and low pressure systems
• Discharge nozzles, pressure relief vents, manifolds, pilot lines and actuation hardware
• Room integrity test services and documentation

Hydrants and hose systems

• Pillar and underground hydrants, hydrant valves and landing valves
• Hose reels, hose cabinets, standpipe assemblies and pressure-regulating devices
• Fire hose in percolating and non-percolating types, branch pipes and nozzles
• Siamese connections, fire brigade inlets and breeching inlets

Detection and alarm

• Addressable fire alarm panels with cause-and-effect programming
• Heat, smoke, multi-criteria and aspirating smoke detectors
• Linear heat detection cable, digital and analogue
• UV, IR, UV/IR and triple-IR optical flame detectors
• Flammable and toxic gas detectors with controllers
• Manual call points, sounders, beacons and voice alarm equipment

Associated supply

• Carbon steel pipe to ASTM A53 and A106 in fire service schedules
• Galvanised and black steel pipe, grooved and threaded
• HDPE and ductile iron buried fire main, fittings and restrained joints
• Butterfly, gate and check valves with supervisory provision
• Pipe coating and cathodic protection materials for buried mains

Engineering support

Send occupancy description, commodity and storage arrangement with heights, site and building layout, available water supply with flow test data, and the applicable code or insurer requirement. We will return a system concept with hazard classification, design density and area, hydraulic calculation summary, pump and tank sizing, and an equipment schedule. For flammable liquid hazards we will state the foam concentrate type, application rate and the basis in NFPA 11, and flag any PFAS regulatory constraint in the destination country.

Certification

UL listing and FM approval documentation for listed components, material certificates to EN 10204 3.1, hydrostatic test certificates, pump performance test curves witnessed to NFPA 20 where specified, foam concentrate batch certificates with quality analysis, room integrity test reports for gaseous systems, and factory acceptance test records for pump sets and proportioning skids.

Logistics

Sprinkler heads, valves, fittings and hydrants generally ship in 2-6 weeks. Fire pump sets and controllers typically 10-18 weeks. Tanks, foam skids and gaseous systems 12-20 weeks. Shipping from Istanbul by road to Europe, the Caucasus and Iraq, and by sea to Gulf, African and Asian destinations.

Send your occupancy and hazard details and we will return a system concept and equipment schedule within five working days. Reach us at info@kaskomakine.com or WhatsApp +90 (537) 521 1399.

Continue Reading: Fire and Safety Series

• Fire Pumps and NFPA 20 Requirements
• Industrial Valves: Complete Guide
• Industrial Process Burners: Types and Selection
• Carbon Steel Pipe: Grades and Standards

Frequently Asked Questions

Q: What design density does a sprinkler system need?
A: Density follows the NFPA 13 hazard classification: about 4.1 mm/min over 139 m² for Light Hazard, 6.1 mm/min for Ordinary Hazard Group 1, 8.1 mm/min for Ordinary Hazard Group 2, 12.2 mm/min over 232 m² for Extra Hazard Group 1 and 16.3 mm/min for Extra Hazard Group 2. Storage occupancies are classified separately by commodity class, storage arrangement and height, and frequently require far higher densities plus in-rack sprinklers or ESFR.

Q: What does NFPA 20 require of a fire pump?
A: The pump must deliver 100% of rated flow at 100% of rated pressure, at least 65% of rated pressure at 150% of rated flow, and churn pressure not exceeding 140% of rated pressure. The driver must have a reliable power source or be a diesel engine with fuel for the required run duration, listed controllers are mandatory, and the installation needs a flow test provision, relief valves, and straight suction piping of at least ten diameters to a split case pump.

Q: What is the difference between a deluge and a pre-action sprinkler system?
A: A deluge system has open nozzles with no thermal elements, so when detection opens the deluge valve every nozzle discharges simultaneously — used for fast-spreading high-hazard risks such as transformers, loading racks and process units. A pre-action system has closed sprinklers and requires both detection actuation and sprinkler operation before water discharges, which protects data centres and archives against accidental discharge.

Q: Which foam concentrate should be used for a flammable liquid fire?
A: AFFF and fluoroprotein foams suit hydrocarbons, but polar solvents such as alcohols, ketones and esters destroy an ordinary foam blanket and require alcohol-resistant AR-AFFF. Fluorine-free F3 concentrates are the regulatory direction of travel because of PFAS restrictions, but they are not drop-in substitutes — they often need higher application rates, different discharge devices and a full system flush of residual fluorinated concentrate.

Q: How do clean agent gas systems extinguish fire?
A: Inert gases such as IG-541 and IG-100 reduce oxygen from 21% to roughly 12 to 14%, below the level most fires can sustain but still survivable for evacuation, and discharge over 60 to 120 seconds. Halocarbons such as FK-5-1-12 and HFC-227ea work mainly by heat absorption at design concentrations of 4 to 9%, discharging in 10 seconds. Both require room integrity testing and calculated pressure relief venting.

Q: Why does a gaseous suppression system need a room integrity test?
A: The agent must stay at extinguishing concentration for a retention period of typically 10 minutes, and a leaky enclosure allows it to escape within a minute, leaving the fire unsuppressed. A door fan pressurisation test quantifies the leakage area and verifies the retention time. The test must be repeated after any building work, because a single new cable penetration can invalidate it.

Q: How large should a fire water tank be?
A: Capacity equals design density multiplied by design area, plus the hose stream allowance, multiplied by the required duration — 30 to 60 minutes for light and ordinary hazard and 60 to 120 minutes for extra hazard and storage. An Ordinary Hazard Group 2 system at 8.1 mm/min over 139 m² plus 950 L/min of hose for 60 to 90 minutes typically needs 130 to 190 m³ before margin, and the fire reserve must be protected from process draw-down.