LPC Sprinkler Rules Technical Bulletin 203: understanding the changes

Overview of updates

Technical Bulletin 203: January 2024: 1

Annex K of BS EN 12845 confirms the number of sprinkler heads required to be tested based on the total number of sprinklers installed in a system. TB203 has always maintained 20 sprinkler heads as a minimum. However, to collect accurate data, batches of different sprinklers from different environments and quantities have been requested. Annex K of BS EN 12845 provides guidance on test numbers and what sprinklers should be evaluated for. What it does not confirm is the standard to which sprinklers are to be tested against.

There is no re-test standard and by default, BS EN 12259-1: 1999 Fixed firefighting systems — Components for sprinkler and water spray systems — Part 1: Sprinklers is adopted, the standard for new sprinklers. The requirements of the TB have always been to keep the numbers at a minimum for clients and contractors. However, data collected over the years has been insufficient to ascertain when exactly sprinkler heads need to be changed.

Previously, in an effort to meet with BS EN 12259-1:1999, function testing and temperature testing was split 80/20 through a minimum of a batch of five sprinklers from each environment. This resulted in four sprinklers being function tested, and one sprinkler being temperature tested. However, failures of temperature testing have resulted in the need to increase this element of the test.

Ensuring operability of sprinkler systems in the future and maintaining them in good working order is required by Part 2, Article 17 of The Regulatory Reform (Fire Safety) Order 2005 (RRO) which covers the maintenance of fire safety systems and outlines the legal obligation on the building owner/occupier’s responsible person to ensure their sprinkler system is suitably serviced and maintained. A well maintained sprinkler system includes essential inspection, service and maintenance routines including a programme for sprinkler head testing.
 

Technical Bulletin 203: December 2024: 1

In the December 2024:1 version of TB203, the split of sprinklers changed to 70/30, requiring seven sprinklers to be function tested, and three sprinklers to be temperature tested from a batch of 10 sprinklers from different environments, for the purposes of compliance testing and to ensure better data is captured.

To provide more accurate data, reproducing the table from Annex K was deemed no longer appropriate. The changes to section TB203.3.9 are based on scientific principles to allow better capture of data for analysis, providing more accuracy in decision making on sprinkler head replacements.

 

Requirements of TB203: January 2024 compared with TB203: December 2024
A summary of the changes is captured below:
 

Previous requirement (TB203: January 2024: 1)	New requirement (TB203: December 2024: 1)
Up to 5000 heads installed = 20 heads tested	Low/medium risk premises = 10 heads tested
Up to 10,000 heads installed = 40 heads tested	High risk premises = 50 heads tested
Up to 20,000 heads installed = 60 heads tested
Where there are different types of sprinkler heads installed a minimum of 5 sprinkler heads of each different type shall be removed and tested	A minimum of 10 sprinkler heads of each different type, per environment, shall be removed and tested

 

Examples of testing numbers based on the new requirements of TB203

School – Ordinary Hazard I-III
False ceiling: 10
Ceiling void: 10
Glazed atrium: 10
Sports hall: 10
Total: 40

Retail Unit – Ordinary Hazard III
False ceiling: 10
Ceiling void: 10
Total: 20 Total

Storage warehouse – High Hazard Storage
Roof system: 50
In-rack system: 50
Total: 100
 

Sprinkler System Service and Maintenance Guidance Records and Checklists
As a result of the changes, the Sprinkler System Service and Maintenance Guidance Records and Checklists and supplementary Template Forms (Appendices) outlining practical guidance for sprinkler system owners and specialist sprinkler maintenance contractors have also been updated and are freely available to download.

Background to the new requirements

Insurer requirements

Insurer members of RISCAuthority, trade associations (BAFSA and the LPCB), and the sprinkler industry experts responsible for producing the LPC Technical Bulletins, reviewed current data on sprinkler failures for heads over 25 years old. Based on the results and compliance with BS EN 12259-1:1999, it was decided to change the number of sprinklers tested based on occupancy classifications.

For low to moderate risk premises (Light and Ordinary Hazard), the number of sprinklers to be tested is a minimum of 10 sprinklers from each different environment within the building. For larger risk premises (High Hazard), it was considered necessary that more sprinklers were tested.

Members of the RISCAuthority Sprinkler Rules Working Group agreed that the associated costs (drain-down, mobilising, supplying lifting equipment, and replacing sprinklers) would not change whether 20 or 50 sprinklers were removed and replaced and therefore the increase was insignificant and justifiable. The Working Group considered it more costly if failures warranted a return visit to remove additional sprinklers for a second test, which insurers have had to request of their clients recently due to reported sprinkler head failures.

Scientific research

Within scientific research it is best practice to test samples in groups of three or more. This allows laboratories to evaluate results to ascertain if a single failure could be an isolated incident, or if there is a failure of a certain type of sprinkler. There can be significant variability between results, particularly with older heads.

When only testing one head, it would not be evident if it could be an anomalous result. With two heads, it is always possible to draw a straight line between two data points, leaving no degrees of freedom for statistical evaluation. With three or more data points, potential inconsistencies in the data can be assessed.

FPA research demonstrates that sampling one head only provides a 55% chance of correctly identifying if a system needs attention. Sampling three heads provides over a 90% chance of correctly identifying if a system needs attention.

Sprinkler head testing

Both quantitative and qualitative tests are carried out during sprinkler heading testing. Function testing is conducted using a custom-built sprinkler rig. Sprinklers for testing are mounted in the rig in their appropriate orientation (pendent, upright, or horizontal) and 0.35 bar of water pressure is then sent to the head. The sprinkler head is activated using a gas operated lance and the performance of each individual head is documented.

 

Operational temperature tests are conducted using either a water bath (maximum safe operational temperature of 90°C) or an oil bath (maximum safe operational temperature of 160°C). A selection of sprinkler heads are placed in the appropriate bath and covered with enough liquid to fully submerge them leaving ~ 20mm of fluid above the deflector plate. Heads are then heated to 20°C below the activation temperature of the sprinkler head and left to reach equilibrium for 10 minutes. The temperature is then increased by 0.5 degrees every minute until the head activates or the maximum temperature is reached.

Water bath

Oil bath

Data collection

Sprinkler heads are tested and inspected for defects that will inhibit the head from full activation in the event of a fire. The sprinkler is visually inspected for dust/dirt, build up of deposits from the environment, and damage to the deflector plate and body. The heads are then subjected to the operational temperature test or the function test.

The operational temperature test investigates the temperature at which the heads will operate in comparison to the stated activation temperature. The test is conducted from ambient temperature to 10°C above the stated upper operating limit of the sprinkler head. The activation temperatures are collected and analysed against a failure criterion.

Statistics collected on operational temperature failures (%) to June 2024

The function test is conducted to investigate the activation mechanism of the sprinkler heads. The heads are fitted into a bespoke function test oven (based on BS EN 12259-1) and heated with a naked flame at 0.35 bar water pressure at the sprinkler head. The flame is used to heat the thermal element of the sprinkler until activation. If the head does not activate, failure tests are then conducted on the head, dependent on the type of failure noted.

Pass/fail numbers of sprinkler heads function tested to June 2024

The test data, coupled with the data from the visual inspection of the head, is then collected and inputted into the report which is submitted to the client. The data is also analysed internally as heads of different ages, types, and environments can reveal trends in deposits and failures. This information is then used for further decision making from a life and property preservation perspective.

% pass/fail rate based on operational mechanism

 

 

Summary

The updated requirements to TB203 allow for better quality data to be captured on sprinklers over 25 years old as the result of research, scientific reasoning, and insurer requirements. The data collected will be subject to a full review to determine many different factors that could lead to sprinkler head failures, such as, but not limited to:

• geographical location
• environment condition (exposed/concealed)
• temperature environment
• hazard classification and hazardous areas
• in-rack versus soffit locations
• sprinkler years of manufacture
• types of sprinklers
• damage to sprinklers
• external or internal.

With sufficient data recorded, guidance on sprinkler head longevity based on risk, will be more accurate and standards can be updated to reflect real world conditions for the benefit of the industry.

Accessing the LPC Sprinkler Rules and Technical Bulletins

The LPC Sprinkler Rules are available via a subscription model which automatically provides access to the latest Technical Bulletin updates throughout the year for an annual fee, ensuring subscribers remain at the forefront of changes for life safety and property protection purposes. Find out more about subscribing to the LPC Sprinkler Rules.