Fire Sprinkler Systems: More Than Pipes and Sprinkler Heads

Automatic sprinkler systems can look deceptively simple. You see a network of pipes, sprinkler heads and a water supply, and it is easy to assume that the system is relatively straightforward. In reality, the effectiveness of sprinkler protection depends on many things that are not immediately visible.

This article explains how we at Java Fire Protection approach sprinkler protection: how we assess the risk, what goes into a sprinkler design, why the water supply matters as much as the pipework, and how we keep a system effective as the building changes. It is written for building owners, developers, facility managers, consultants and MEP contractors in Lebanon. Where it helps, we point to the references behind our practice:

NFPA 13, Standard for the Installation of Sprinkler Systems;
NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection;
NFPA 22, Standard for Water Tanks for Private Fire Protection;
NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems;
Lebanon's public safety decree.

Our view in brief

We start from the risk inside the building, not from the pipework.

We design to NFPA 13 and prove the design with hydraulic calculations.

We treat the water supply, pumps and their power as part of the system.

We install only listed and approved components.

We design, install, test, commission and maintain sprinkler systems ourselves, and we reassess them when the building changes.

How does a sprinkler system work?

Each sprinkler is a heat-activated valve. When the heat of a fire reaches a sprinkler's rated temperature, that sprinkler alone opens and discharges water onto the fire below it. Only the sprinklers exposed to enough heat open. The rest stay closed. NFPA's research on fires in the United States, U.S. Experience with Sprinklers, shows that in the great majority of fires where sprinklers operate, five or fewer sprinklers open.

Once water flows, a flow switch or alarm valve raises the alarm. Where the building has a fire alarm system, the sprinkler system reports to it, and the control valves are monitored so that a closed valve is noticed.

There are four main system types, and choosing between them is part of the design:

System type	How it works	Where we typically use it
Wet pipe	Pipes are permanently filled with water under pressure; water discharges as soon as a sprinkler opens.	Most offices, hotels, hospitals, retail and car parks.
Dry pipe	Pipes hold pressurised air or nitrogen; water enters only after a sprinkler opens and the air escapes.	Unheated areas where water in the pipes could freeze. Freezers often use double-interlock pre-action instead.
Pre-action	Pipes are dry and monitored; a separate detection system (and, in double-interlock systems, also a sprinkler opening) lets water in. The sprinklers are closed and still open individually.	Archives, museums, freezers and areas where accidental discharge would be very costly.
Deluge	All sprinklers or nozzles are open; a detection system releases water through every one of them at once.	Special hazards; transformers and fuel-handling areas are usually protected by water-spray systems designed to NFPA 15.

Why does the risk inside the building come first?

Because the hazard decides how much water is needed, where, and for how long. The starting point is always the risk inside the building. A warehouse storing combustible products is very different from an office. An automotive facility is different from a hotel. Storage height, storage arrangement, processes, building configuration and available water supply can all change the way sprinkler protection needs to be designed.

NFPA 13 expresses this through occupancy hazard classifications. Each classification sets a design point: a water density applied over a design area, plus an allowance for hoses and a minimum duration.

Classification	Typical examples	Design point (NFPA 13)	Hose allowance and duration
Light hazard	Offices, hotel guest areas, hospitals, schools, residential	0.10 gpm/ft² (4.1 mm/min) over 1,500 ft² (139 m²)	100 gpm (379 L/min), 30 min
Ordinary hazard, Group 1	Bakeries, laundries, restaurant service areas, beverage manufacturing, mechanical rooms	0.15 gpm/ft² (6.1 mm/min) over 1,500 ft² (139 m²)	250 gpm (946 L/min), 60–90 min
Ordinary hazard, Group 2	Car parks and car showrooms, workshops, repair garages, printing plants, mercantile, stages	0.20 gpm/ft² (8.2 mm/min) over 1,500 ft² (139 m²)	250 gpm (946 L/min), 60–90 min
Extra hazard, Groups 1 and 2	Upholstery with plastic foams, flammable liquid spraying, paint dipping, plastics processing	0.30–0.40 gpm/ft² (12.2–16.3 mm/min) over 2,500 ft² (232 m²)	500 gpm (1,893 L/min), 90–120 min
Storage	Warehouses and storage areas, generally above 3.7 m (12 ft), and lower for plastics (above 1.5 m / 5 ft) and some other commodities	Set by commodity class, storage height and arrangement, often with in-rack or specialised sprinklers	Set by the storage criteria

The lower duration in each range is allowed only where waterflow and supervisory signals are monitored at an approved, constantly attended location. In most Lebanese buildings, that means designing to the higher figure.

A warehouse is where this matters most. The same building can need very different protection depending on whether it stores bottled water or plastic packaging, and whether goods are stacked to 3 m or racked to 9 m. A change in what is stored can quietly invalidate the original design, which is why NFPA 25 expects the owner to have the system evaluated before changing the use, the process or the materials stored.

What goes into designing a sprinkler system?

Hazard classification, sprinkler layout, hydraulic calculations, the water supply and coordination with every other trade. At Java, we therefore begin by looking at the occupancy, the hazard, the applicable requirements and the available water supply before moving into detailed design. Depending on the project, this can involve:

Hazard classification, area by area, including storage.
Sprinkler layout: sprinkler type, K-factor, temperature rating, spacing and distance from walls, ceilings and obstructions.
Hydraulic calculations, which prove that the most demanding area of the building receives the required density at the required pressure, from the water supply actually available.
Pipe sizing, which follows from the hydraulic calculations.
Zoning and control valves, so that each area can be isolated, monitored and tested.
Fire pumps and water storage, sized to the hydraulic demand and its duration.
Seismic protection: bracing and flexibility where required. Lebanon has significant seismic hazard, and its public safety decree also covers protection against earthquakes.
Coordination with the architectural and MEP services: ducts, beams, cable trays, lighting and false ceilings all affect where water can reach.

The purpose of all this work is not simply to satisfy a drawing requirement. It is to make sure that when the system is called upon to operate, the water can reach the right place in the required manner.

For a leading airport and airline service provider, our review of the estate found that the existing water supply was not sufficient for the protection required, and we designed a new fire water network as part of the work.

Is the building's water supply enough?

Often not, in Lebanon, which is why we check it before designing anything else. Many buildings rely on tanks rather than a dependable public main, and fire water is sometimes shared with domestic water. A sprinkler design is only as good as the water and pressure behind it.

Tank size follows from the hydraulic calculation: the sprinkler demand, plus the hose allowance for any hoses or hydrants fed from the tank, multiplied by the required duration. It is measured as usable volume above the pump suction, and it cannot be read from a rule of thumb.
Shared tanks can work only if the fire reserve is protected, for example by placing the domestic outlet above it, so that domestic use can never draw the tank below the volume reserved for firefighting.
Fire pumps are installed and tested to NFPA 20. Where the normal power supply is not reliable, NFPA 20 requires an alternate power source, such as an on-site standby generator, unless a back-up diesel-driven fire pump is installed.
Power and fuel. Many of the pumps we install and maintain in Lebanon are diesel driven for this reason, with their own fuel supply, batteries and controller.

Why do we install only listed and approved components?

Because NFPA 13 requires the devices and materials essential to the system's operation to be listed, and because an unlisted part is an unknown. We install sprinklers, valves, pumps and controllers that are UL listed or FM approved, supplied with their datasheets and listing documentation. A listed sprinkler carries a sprinkler identification number (SIN), usually stamped on the deflector, which can be checked against the manufacturer's data and the listing.

How do we install and commission a sprinkler system?

We install to the approved drawings, then prove the system works before handing it over. Our commissioning includes:

Hydrostatic test. New piping is tested at 200 psi (13.8 bar) for two hours, or at 50 psi (3.4 bar) above the maximum working pressure where that is higher.
Flushing. Underground and lead-in mains are flushed before connection, to NFPA 24.
Alarm and valve tests. We test waterflow alarms, valve supervision and the connection to the fire alarm system.
Main drain test. We record the baseline pressure that future annual tests are compared against.
Pump acceptance test. We test fire pumps at churn, rated flow and peak flow, to NFPA 20.
Documentation. We hand over as-built drawings, the hydraulic calculations and the test certificates. We also provide the hydraulic design information sign at the riser, and a spare sprinkler cabinet with the correct sprinklers and wrench.

Why doesn't our responsibility end at handover?

Because buildings change continuously, and a sprinkler system only protects the building it was designed for. The responsibility does not end when installation is completed. Storage arrangements can change, sprinkler heads can become obstructed or damaged, valves can be closed, systems can deteriorate and buildings can be extended or modified. A sprinkler system that once complied with the original design may no longer provide the same level of protection if the building around it has changed.

The faults we find most often in the field include:

control valves closed or partly closed, often after maintenance work;
sprinklers painted, covered or damaged;
storage stacked too close to sprinklers, blocking the spray;
new partitions, ducts or false ceilings installed without moving sprinklers;
fire pumps left in manual mode or with their batteries or fuel run down;
fire water drawn down for domestic use;
a warehouse now storing goods the original design never considered.

What does an NFPA 25 inspection involve?

A schedule of inspections, tests and maintenance, from weekly checks of valves and pumps to tests every five years and beyond. NFPA 25 sets the minimum frequencies. The main ones for a wet sprinkler system:

Frequency	What is checked
Weekly or monthly	Control valves are open and secured: weekly where sealed, monthly where locked or electronically supervised. Fire pumps are run without flow: weekly for diesel pumps, and weekly for electric pumps that take suction from tanks (as most in Lebanon do) or serve buildings beyond the fire brigade's pumping reach; otherwise monthly.
Quarterly	Waterflow alarm devices and gauges are inspected; mechanical waterflow alarms are tested.
Semiannually	Vane-type and pressure-switch waterflow alarms are tested.
Annually	Sprinklers, pipework and hangers are inspected from the floor; the main drain test is carried out and compared with the baseline; control valves are operated through their full range; the fire pump is flow-tested; spare sprinklers and the hydraulic design sign are checked.
Every 5 years	The internal condition of the piping is assessed; gauges are replaced or checked against a calibrated gauge.
After 20 to 50 years	Sprinklers are replaced, or samples are sent for laboratory testing: standard-response sprinklers at 50 years, fast-response at 25 years, early suppression fast-response (ESFR) and dry sprinklers at 20 years, then every 10 years. In harsh environments, every 5 years.

The owner is responsible for making sure this programme is carried out. At Java, we carry it out, record every visit, and report impairments and deficiencies with a clear recommendation, so that a closed valve or an obstructed sprinkler is corrected rather than simply noted.

What do Lebanese law and the codes require?

Lebanese law sets the framework, and the standards provide the technical detail. Lebanon's public safety decree is Decree No. 14293 of 2005, as amended in full by Decree No. 7964 of 2012:

One standard per subject. Article 1(10) applies Lebanese standards, or, where none exist, those adopted in the EU, the US or Canada. Article 3 requires a single source per safety subject. We design sprinkler systems to NFPA 13 and its companion standards, rather than mixing US and European requirements.
Drawings under technical control. Where applicable, we work to the drawings approved by the technical control bureau under Article 5.
Changes to buildings. Article 4(1) brings modifications, additions and changes of use within the decree. A fit-out, an extension or a new tenant is a moment to look at the sprinkler design again.
Maintenance. Article 4(4) makes the owner, or the owners' association, responsible for the periodic maintenance of the building and its equipment.

Beyond the decree, NFPA 101, the Life Safety Code, requires sprinklers throughout many new buildings, including hotels, apartment buildings and high-rise buildings. Insurers may also set their own requirements, sometimes based on FM (formerly FM Global) Property Loss Prevention Data Sheets.

Why do we see sprinkler protection as a lifecycle?

For this reason, we see sprinkler protection as a lifecycle rather than a project: assess, design, install, test, maintain and then reassess. That philosophy also reflects the type of relationship we prefer to have with our customers. We do not want to install a system, hand over the project and disappear. Fire protection works best when there is continuity between the people who understand the risk, the people who install the system and the people responsible for keeping it operational.

That continuity is an important part of what we believe good fire protection should look like.

Planning a new building, changing how a warehouse is used, or unsure whether an existing system still matches the building? Speak with our team about a sprinkler survey.

Frequently asked questions

Does Java Fire Protection install sprinkler systems?

Yes. We design, install, test, commission and maintain automatic sprinkler systems, together with fire pumps, water storage, standpipes and hydrants. The same team that assesses the risk stays responsible for keeping the system operational.

Do all the sprinklers go off at once in a fire?

No. Each sprinkler opens individually when the heat at that sprinkler reaches its rated temperature. Only the sprinklers over the fire operate. The exception is a deluge system, which is used for special hazards and discharges through all its sprinklers or nozzles at once.

Do residential buildings in Lebanon need sprinklers?

It depends on the building and the standard its design follows. Under NFPA 101, which we apply, all new apartment buildings, hotels and high-rise buildings, and even new one- and two-family dwellings, require sprinklers throughout. NFPA 101 is not itself Lebanese law. We assess each building against the standard chosen for it and the requirements of the authority approving it.

How big should the fire water tank be for a building in Lebanon?

The tank is sized from the hydraulic calculation: the water the sprinkler system needs, plus the allowance for any hoses or hydrants fed from the tank, multiplied by the duration NFPA 13 sets for the hazard. That duration is 30 minutes for light hazard, 60 to 90 minutes for ordinary hazard, and 90 to 120 minutes for extra hazard. The lower figure applies only where alarms are monitored at a constantly attended location. Storage buildings can need more. We calculate it for each building rather than use a rule of thumb.

Diesel or electric fire pump, given power cuts in Lebanon?

Where the normal power supply is not reliable, NFPA 20 requires an alternate power source for an electric fire pump, such as an on-site standby generator, unless a back-up diesel-driven pump is installed. In Lebanon, a diesel pump is often the more dependable choice, provided its fuel, batteries and weekly test run are looked after.

Can a fire pump draw from a shared water tank or a well?

From a shared tank, yes, if the fire reserve is protected so that domestic use can never draw the tank below it. A well can be a source only if testing proves it delivers the required flow for the required duration. It then needs a vertical turbine fire pump installed to NFPA 20. We check both during the survey.

How do I verify that a sprinkler or fire pump is genuinely UL listed or FM approved?

Check the exact model in UL's online certification directory (UL Product iQ) or in FM Approvals' Approval Guide. For sprinklers, match the sprinkler identification number (SIN), usually stamped on the deflector. Ask the supplier for the datasheet and listing documentation. We provide these with every system we install.

My insurer requires sprinklers and a fire pump before renewing our factory policy. What should I do first?

Get the insurer's requirement in writing, including the standard it expects. Then have the site surveyed: the hazards, the storage, the existing water supply and the power available for a pump. That survey decides the design, the tank and the pump. We can carry it out and prepare the documentation the insurer needs.

What does an NFPA 25 sprinkler inspection involve?

It covers:

weekly or monthly checks of valves and pumps;
quarterly checks of alarms and gauges;
an annual inspection of sprinklers and pipework, with a main drain test and a pump flow test;
longer-term work: the five-year internal pipe assessment, and replacing or laboratory-testing sprinklers from 20 to 50 years depending on their type.

The owner is responsible for making sure it is done.

References

NFPA 13, Standard for the Installation of Sprinkler Systems, 2025 edition.
NFPA 15, Standard for Water Spray Fixed Systems for Fire Protection.
NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection, 2025 edition.
NFPA 22, Standard for Water Tanks for Private Fire Protection, 2023 edition.
NFPA 24, Standard for the Installation of Private Fire Service Mains and Their Appurtenances, 2025 edition.
NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, 2026 edition.
NFPA 101, Life Safety Code, 2024 edition (a 2027 edition has since been published).
NFPA, U.S. Experience with Sprinklers.
Decree No. 14293 of 11 March 2005 on public safety in buildings and facilities, lift installations, and protection against fire and earthquakes, as amended in full by Decree No. 7964 of 7 April 2012 (Lebanon).