Sprinkler installations

09 June 2010
Lessons from losses 5/2010. Sprinklers are automatic extinguishing systems that are reliable and have a good damage-limitation effect on fire. When the sprinkler head opens, water is released. From a statistical point of view, this provides a high degree of functional reliability.

Nevertheless, some deficiencies can occur. What are the most important causes, and what can be regarded as the greatest challenges? From a business point of view, sprinklers not only prevent damages but have a direct effect on settlements, if installed incorrectly.

Missing documentation

If there is no documentation on the system, there is no way of knowing whether the installation has critical defects. Insurance companies in Norway require that sprinkler installations should be documented via an inspection report from an FG-approved inspection company, and that the report is entered in the ESS web database. Many sprinkler installations in Norway are not documented in this way, and our task is to set documentation requirements for customers. Both the owners and ourselves will then inspect any deficiencies in the installation, and can make the necessary improvements.

General flaws in sprinkler installations in Norway:

a. Inadequate water supply

When designing a sprinkler installation, checks should be made to determine whether sufficient water will be available from the public mains, or whether it will be necessary to construct an on-site tank with pumps. The installation is often constructed on the assumption that municipal water mains can provide an adequate supply.

However, the water company provides drinking water to its customers, and it may place restrictions on carrying out draw-own tests. Booster pumps are also an issue. In cases where the mains can supply sufficient water, but where a booster pump has to be fitted ahead of the sprinkler valve, it is difficult to carry out the necessary test-running of the pumps.

b. Sprinkler installation incorrectly designed for the level of risk it must face.

There may be changes which need increased extinguishing capacity, e.g. if a production site becomes a stores unit, or if goods with a higher fire risk, with increased content of plastic materials or packaging, are stored. Warehouses or shopping centres present more of a storage risk (HHS) than an older shop (OH3), as it is referred to in official regulations.

c. Excessive material stored in relation to the sprinkler’s extinguishing capacity.

The owner of a storage building who wishes to make maximum use of storage capacity may pile material ceiling high. This might restrict the sprinkler head spray pattern. For OH installations there should be at least 50 cm from the sprinkler to the top of the stored material, and in store buildings (HHS) the clearance should be 100 cm.

Smoke ventilation is another area that should receive proper attention. If smoke ventilators start up before the sprinklers, it is possible for hot smoke from the fire to be drawn away from the fire and start up sprinklers in areas outside the actual fire zone. Smoke spreading from the fire zone will be cooled, but the fire itself will not be affected.


Sprinkler installations should always be delivered with a test, service, and maintenance programme. Legislation varies from country to country. In Norway, it is required by law that the owner of a building must ensure that the installation functions in the manner for which it is intended. Part of this obligation includes an annual inspection of the sprinkler installation by qualified personnel. In insurance agreements this is often included as a requirement in safety regulations.

The detailed inspection and maintenance programme covers frequent inspection patrols. Pressure checks should be made, as well as visual inspections of sprinkler branches, shut-off valves, and alarm tests at weekly, monthly, quarterly, and bi-annual intervals. Logbooks should be kept to ensure that these inspections are carried out.

Requirements and obligations

Insurance companies, as well as national building regulations in each country, set requirements for sprinklers in certain types of businesses or buildings over a certain size. It may be a storage or production facility with very high fire loads, storage of flammable materials, or buildings that carry an enhanced danger to health. On the basis of experience, we know that sprinkler installations are often regarded as major cost items in both new and existing buildings.

However, in terms of write-off over time, the costs of a sprinkler are not significant in comparison to total building costs. Also, if it is possible to make a rapid return to full operation and regain market position after a fire, the costs of a sprinkler system will be a relatively small price to pay. 

Tore Aarnes and Anders Rørvik Ellingbø