Automatic Sprinkler Systems

An automatic sprinkler system discharges water onto a fire from heat-activated heads above it, controlling or extinguishing the fire before it spreads. It comprises a water supply (town main, storage tanks, fire pumps), control valves and alarm valve sets, pipework (risers, mains, branch lines), sprinkler heads, flow and tamper switches connected to the fire alarm, and a fire brigade booster or inlet. Each head opens independently when its glass bulb or fusible link reaches its rated temperature; only heads near the fire operate.

A sprinkler system is designed for a hazard: the building's use, ceiling heights, and in warehouses the commodity, packaging, storage height and racking. When the use changes, the system may no longer be adequate even though nothing in it has deteriorated. This is the most important and most overlooked sprinkler finding in industrial and retail buildings.

Codes have extended sprinkler requirements over time: new residential buildings over 11 metres in England since 2020, new apartment buildings of four storeys and more in Australia from the 2019 code amendments, and most new multi-family buildings in the United States. Older buildings of the same type are often unsprinklered, which is a fire safety strategy matter rather than a defect.

What shortens life:

• Water left in dry pipe systems after trip tests, which corrodes pipe from the inside.
• Microbiologically influenced corrosion (MIC) in wet systems, producing pinhole leaks.
• Oxygen introduced by frequent draining and refilling.
• Corrosive atmospheres: car parks, swimming pools, cold stores, industrial processes.
• CPVC contact with incompatible products: some cable sheaths, sealants, spray foam and oils.

Change of hazard

A warehouse designed for low storage of ordinary goods that now holds high-piled plastics, or racking taller than the design height, overwhelms the system: too few heads open, too little water, and the fire outruns it. Retail and industrial tenancies change commodity and layout far more often than sprinkler systems are redesigned.

Obstruction and shielding

Storage stacked too close to heads, new ductwork, cable trays, lights and partitions below or beside heads, and ceilings lowered in fit-outs block the spray pattern or create unsprinklered areas. Heads painted, taped, bagged during works or loaded with dust and grease respond late or not at all.

Internal corrosion and leaks

Dry pipe systems corrode where trapped water sits at low points; wet systems suffer MIC, which produces tubercles and pinhole leaks and can block small pipes. Corrosion products can block heads. Leaks in occupied buildings cause damage and lead to systems being shut down.

Impairments

Control valves closed for works and not reopened leave parts of a building unprotected. Supervised valves report closure to the fire panel; unsupervised valves do not.

Water supply decline

Town main pressures fall as networks change; tanks lose capacity to sediment and corrosion; pumps deteriorate. A system that met its design at commissioning may not now, and only a flow test shows it.

Head defects and recalls

Certain sprinkler heads have been subject to recalls; corroded heads and those in hot or corrosive areas can fail to open; heads replaced with the wrong temperature rating, response type or coverage break the design.

CPVC cracking

CPVC sprinkler pipe used in residential and light hazard buildings cracks when exposed to incompatible chemicals, sometimes years after installation.

Freezing

Wet pipes in unheated spaces freeze and burst; dry systems with poor drainage freeze at low points.

In the building

• Storage within the clearance zone below heads; racking taller than the design; changed commodities.
• Heads painted, taped, bagged, loaded with dust, or corroded.
• New partitions, ceilings, ductwork and lights below or around heads; rooms without heads.
• Signs of leaks and corrosion on pipework; drips and staining below.
• Spare head cabinet: stocked with heads matching those installed.
• Valve room: control valves open and secured; gauges reading; signage.
• Booster or brigade inlet accessible and in good order.

In the records

• Design certificate and hydraulic calculations, with the hazard classification and storage design.
• Routine service records: weekly or monthly valve checks, alarm tests, flow tests.
• Long-interval inspections: internal pipe inspections and head sampling.
• Impairment log.
• Leak history.
• Changes of use or tenancy since design.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A fire services engineer leads, with the sprinkler maintenance contractor; for storage buildings, the review is against the storage design standards.

• Design review: design certificate, hazard classification, hydraulic calculations, storage design basis, against the building's current use, layout and storage.
• Coverage and obstruction survey of all areas, including new rooms, ceilings and storage.
• Head survey: type, temperature, response, condition, recalls, painting and loading; sample removal and laboratory testing at the age the standard sets.
• Internal pipe inspection: flushing, opening at representative points, internal camera inspection, and pipe sampling for MIC where leaks occur.
• Water supply flow test at the design point.
• Valve inspection: control valves open and supervised; alarm and dry pipe valves internally inspected.
• Records review: service history, impairments, leaks.

The report should state whether the system matches the current hazard, coverage and obstruction issues, water supply adequacy, internal condition, and works needed.

• Restore protection: open and supervise valves; remove covers; clear storage from below heads; manage impairments with permits and fire watches.
• Match storage to the system: reduce storage height or change commodities, or redesign the system (more water, larger heads, in-rack sprinklers).
• Coverage additions after fit-outs.
• Head replacement: recalled, painted, corroded or aged heads.
• Corrosion treatment: replace corroded sections; nitrogen inerting of dry and pre-action systems; MIC treatment and replacement of affected pipe.
• Water supply improvement: pumps, tanks, larger connections.
• Dry system drainage and auxiliary drains at low points.
• CPVC protection: identify and isolate incompatible products; replace cracked sections.

• Spare heads: restock the spare head cabinet with heads matching each type installed, with the correct wrench.

Routine and long-interval inspections are recurring contracts, with lump sums for internal pipe inspections, head sampling and flow tests. Head replacement is per head. Coverage additions per head with design. Redesign for storage is a lump-sum project, possibly with pumps and tanks. Pipework replacement is by length, with access and ceiling works dominating in occupied buildings.

Inspections and safety rectification are code compliance; pipework and heads at end of life are lifecycle; repairs are repairs and maintenance. A change of use that requires redesign is usually borne by the project that changes the use.

• Australia. The National Construction Code sets where sprinklers are required, including newer requirements for apartment buildings; AS 2118.1 governs design and installation; AS 1851 sets routine service, including weekly or monthly checks, annual flow tests, and long-interval inspections and testing; sprinklers are essential safety measures with annual certification.
• United Kingdom. Approved Document B sets where sprinklers are required, including new residential buildings over 11 metres; BS EN 12845 with the LPC Rules covers commercial systems and BS 9251 residential systems, with weekly tests, quarterly to annual inspections and long-interval inspections; insurers often set additional requirements.
• United States. NFPA 13, 13R and 13D govern design; NFPA 25 sets inspection, testing and maintenance, including weekly to annual checks, five-yearly internal pipe assessments, and testing of sample heads at 50 years (20 for fast-response) and periodically thereafter; the International Building and Fire Codes set where sprinklers are required.

• Design certificate, hazard classification and hydraulic calculations.
• Routine service records and annual certification.
• Flow test results against the design curve.
• Internal pipe inspection and head sampling reports.
• Impairment log.
• Leak and repair history.
• Storage arrangement and commodity description for warehouses.
• Insurer surveys and recommendations.

• Records of recalled heads identified and replaced.
• Fit-out records showing sprinkler alterations and who certified them.