Is your sprinkler system still fit for purpose?

The critical role sprinkler systems play in life safety and fire suppression is well known by building owners. However, few understand exactly how they work, why they need to be inspected and how regularly this work should be done to ensure optimal system performance.

The documented efficacy of sprinkler systems is stark. In properties where well-maintained sprinklers are installed there has been no loss of life to date in the UK.

The LPC rules incorporating BS EN 12845 states the need for routine inspection of sprinkler systems internally and externally throughout its life. A well-maintained sprinkler system can last for many years before needing replacement, making regular inspections vital to ensure you get the maximum life from your system. The standards do also call for a more intrusive inspection at 25 years which is often overlooked.

The following actions are to be undertaken as part of this 25-year inspection:

  • Remove a representative number of sprinkler heads for 3rd party laboratory inspection.
  • Inspect sprinkler pipework internally and externally looking for evidence of corrosion.
  • Flush the sprinkler system to capture and inspect any debris.

These works should be carried out by competent engineers and the specific tests and work required will vary depending on the site and system installed.

Different methods of inspection are necessary for different parts of the system. Here, we will give an overview of the methods used for the pipes and the sprinkler heads.

Sprinkler Pipework

New methods of inspecting the integrity of pipework are emerging e.g. ultrasonic scanning however the simplest way is to remove sample sections of pipe.

In this way the internal bore can be fully inspected which may reveal further important details, such as pipe corrosion.

Corrosion can appear in different forms and lead to different types of damage which may be a precursor to a failure state.


Sprinkler heads should be removed from each system for 3rd party inspection. These inspections are specific laboratory tests against pre-defined criteria.

The number to be removed will depend on the size and type of the system being inspected. Each head will be replaced with a new head to ensure the system can be returned to operational. The removed heads will then be sent away and tested in the following ways:

  • Visual inspection
  • Function test
  • Operating temperature test
  • K-factor variance
  • Thermal response

During testing, typical issues found include paint contamination, deflector damage, external and internal corrosion, discoloration, and foreign materials in the waterway. 

Furthermore, the function test will establish if the equipment is working normally. Sprinkler heads activate either by glycerine filled bulbs bursting or solder links melting in fire conditions, allowing water to flow through the pressurised pipework. If either fail, the control valve cannot deliver its mechanical and electrical alarm signal and the required water will not flow.

LPCB rules state a zero-fail tolerance must be applied to all parts of a sprinkler head for it to pass its function test inspection. Anything else is an unacceptable risk and replacement of all heads in the system is mandatory.

Likewise, thermal response tests are a zero-fail situation. Contemporary sprinkler heads are allowed to operate within lower and upper limits to be used safely, whereas older models may not be able to meet these tolerances as set out in BS EN 12259. [Please check this, taken from original document]

Where an individual sprinkler head fails this testing and cannot meet the required standards, it and others must be replaced.

Flushing the system

Following the inspection of the pipes and removal of the sprinkler heads, the final stage of the inspection is flushing the system.

A sieve is used to capture any foreign debris present in the pipes for inspection.

The British Standards rule that if any flushed particles greater than 5mm diameter are identified further investigation is required to find to determine areas of corrosion in the pipework.

If foreign debris is found in the system, it is usually either a build-up of corroded steel flakes which have fallen away from the inside of the pipes, or limescale due to the qualities of the water in the local area. In some rare cases, it can even be the case that stones have found their way into the pipes via the water supply.

This flushing inspection process can be especially tricky in older systems when it wasn’t mandatory for compliant systems to have flushing valves.

If you would like to learn more about a 25-year inspection for your facility, please contact the Alpine Service Team today on 0161 791 4511.