Introduction

The LPC (Loss Prevention Council) rules for automatic sprinkler installations are the most common standards applied to commercial and industrial sprinkler installations in the UK. They are made up of British and European Standard 12845 and Technical Bulletins which are published by the Fire Protection Association (FPA). When the sprinkler specification refers to LPC standards, the technical bulletins take precedent over BS EN 12845 where applicable (although in certain cases deviations can be agreed by Authorities having Jurisdiction).

Section 5 of BS EN 12845 (2015) lays out guidance for the extent of sprinkler protection within a sprinkled building. Not surprisingly, it starts by stating that “Where a building is to be sprinkler protected, all areas of that building or of a communicating building shall be sprinkler protected” except in certain circumstances which are then explained (a very similar statement is made in TB 206:2015). It makes sense that, in general, all areas of a sprinklered building should be sprinkler protected as if a fire takes hold in an un-sprinklered area then it can grow rapidly. If/when the fire then spreads to a sprinklered area of the building, the sprinkler system will not be able to fight the fire as effectively due to the fire already being a substantial size and initially the sprinkler heads are likely to be at the side of the fire rather than above.

However, there are reasons why sprinkler protection may not be applied to the entire building and this white paper seeks to summarise what these reasons are, what is permissible and what is not, what effect this has on the passive fire protection required and how TB206 particularly affects buildings over 30m high.

Please note that this white paper does not cover sprinkler protection of communicating buildings or sprinkler coverage in ceiling voids.

Necessary Exceptions

Due to water being used as the primary firefighting medium, sprinkler protection should not be fitted in areas where a new hazard may be created (i.e. doing more harm than good). One example of this is where silos or bins are being stored where the contents are substances which expand on contact with water. Chemicals such as Polyacrylamide for example (which is used for production of paper, contact lenses and adhesives) would expand on activation of sprinkler heads and would cause obstructions for people trying to exit the building.

TB206.4.2.2 (2015) states:

“Sprinkler protection shall not be provided in the following parts of a building or plant:

Silos or bins containing substances which expand on contact with water
In the vicinity of industrial furnaces or kilns, salt baths, smelting ladles or similar equipment if a risk assessment indicates that the hazard would increase by the use of water in extinguishing a fire
Areas, rooms or places where water discharge may present a hazard”

In these instances, alternative protection should be considered, such as gas or powder.

As you can imagine, most of these scenarios would likely only apply to industrial manufacturing or processing plants rather than typical life safety buildings such as offices, retail and high-rise.

Permitted Exceptions

Alongside the necessary exceptions are permitted exceptions which are areas where sprinkler protection can be omitted as long as this is agreed and signed off by the Authority Having Jurisdiction. TB206.4.2.1 (2015) states:

“Sprinkler protection shall be considered but may be omitted following a sufficient risk assessment of the fire load in the following cases:

Washrooms and toilets (but not cloakrooms) lined with non-combustible materials and which are not used to store combustible materials
Enclosed staircases, spaces below stair headings (but not rooms above a stair), and enclosed vertical shafts (such as lifts or service shafts) containing no combustible material and constructed as a fire resistant compartment (see TB206.1.1 and TB206.4.5)
Rooms protected by other automatic fire suppression systems (such as inert gas, powder or water spray)
Wet processes such as the wet end of paper making machines
Rooms or compartments containing electric power distribution apparatus such as switch gear and transformations, and used for no other purpose(s)"

It is important to remember that toilets (for example) are not just automatically left as un-sprinkler protected. TB206 (2015) clearly states that sprinkler protection must be considered, that a risk assessment should be carried out to support the omission of sprinklers, fixtures and fittings must be chosen carefully for low fire load and that combustible materials must not be stored there. This is also why a quarterly hazard review is necessary to ensure that, for example, an enthusiastic member of staff has not installed some shelves to store spare toilet rolls and cleaning chemicals in the un-sprinklered toilets after the building is handed over!

Having said that, it is common for buildings to make use of these permitted exceptions as it saves money on protecting areas that are less likely to pose a fire risk.

It is also important to remember that TB206.4.2 (2015) also states that “passive fire protection measures shall be installed in accordance with TB206.4.5 and table TB206.T2 in any area not sprinkler-protected” which is explained in more detail later on in this document.

Passive Fire Protection of and between Fully Sprinklered Compartments

TB206.4.1.1 (2015) and the accompanying Table TB206.T1 describes passive fire protection that is recommended between fully sprinklered compartments (the table makes reference to the FPA Design Guide for the Fire Protection of Buildings: Protected Zone: 2004, table 2.2 Compartmentation – recommended fire resistance). This table states, for example, that in an office block between 5 and 18m tall, 60mins fire resistance is recommended between fully sprinklered compartments.

(This is for clarification/comparison and is not relevant to the aims of this document)

Separation of Un-sprinklered and Sprinklered Areas within a Building

TB206.4.5 (2015) deals with situations where necessary or permitted exceptions have been used to omit sprinkler protection in certain areas of the building.

TB206.T2 (2015) gives recommended fire resistances between un-sprinklered and sprinklered compartments of a building. Whilst a single room may not be considered to be a compartment, any room that is not sprinkler protected will form part of a compartment that is not fully sprinkler protected.

The table shows that in many instances, fire resistance will need to be increased where un-sprinklered compartments (or parts of compartments) are present. For example, an office block between 5 and 18m tall would now require 90mins fire resistance (as opposed to 60mins where all compartments are fully sprinklered).

This table contains some important implications for certain types of buildings that are over 30m tall. It states that un-sprinklered compartments are “not permitted” in offices, shops, commercial/retail warehouses, superstores, assembly and recreation buildings, industrial buildings (OH1 to HHP), storage and other types of non-residential buildings over 30m.

For example, if you refer to the table under the application “office”, under the category “over 30m” the table states “not permitted”. This is the same for the other category types mentioned above.

Some may argue that this rule is unfair or incorrect. One argument is that if non-sprinklered areas in an office block (such as small server rooms on each floor) that is 29m high requires 120min fire resistance then why can’t, in a 40m building, the floors up to 30m apply this rule and sprinkler protect all areas of floors over 30m. In response to this, I would say that the main principle that can be taken from these rules is that as buildings get taller, the greater the distance that people highest up will have to travel to escape the building and therefore the longer it will take for a full evacuation if this is necessary. An area that is not sprinkler protected has as a greater potential to harbor a fire that could require a full evacuation and therefore it is right that all floors should be treated the same. The worst case scenario would arguably be a fire on the 3^rd or 4^th floor of a building; high enough up to make access by fire & rescue services difficult and a long distance for people on the top floor to get past it to safety.

Having said that, fire engineers and authorities having jurisdiction can consider each building independently and make a judgment which can be agreed and signed off by all parties.

I am also aware that in many cases, sterile access stairways which would be used by the fire & rescue service in the event of a fire are kept un-sprinklered. This is because sprinkler activation in this area would limit visibility and make access more difficult.

Solutions

For buildings that fall into the “not permitted” category for un-sprinklered areas, sprinkler protection must be installed. TB206 does not permit the use of other fixed firefighting equipment to be used instead of sprinkler protection. For toilets and stairwells this is simply a case of extending the pipe runs and adding additional sprinkler heads. This is perhaps more complicated for rooms where the discharge of water would cause considerable damage such as rooms that host a building’s IT infrastructure (server rooms) or rooms where electrical or sensitive equipment is stored.

If a fire were to take-hold in a server room, for example, that generated enough heat to set off the sprinkler system then the lives of the people in the building are at risk. Therefore the value of the equipment and the commercial disruption caused by the sprinklers activating are now of very little consequence in comparison. However, building owners and insurers are understandably nervous about sprinkler heads activating as a result of a malfunction or damage (accidental or malicious). Sprinkler systems that feature ‘double knock’ activation have been around for many years and are often used in warehouses with valuable stock which would be damaged by water. These systems often use smoke or heat detectors which also have to activate for water to be released (i.e. two inputs to activate). These types of systems are expensive, impractical for small areas of a larger building and are not considered suitable for life-safety application.

Gemini sprinkler heads provide ‘double knock’ activation in a neat, easy to install unit which fits onto standard sprinkler pipework and forms part of the main sprinkler infrastructure. As its name suggests, the unit has two sprinkler heads positioned about 130mm apart (water will only ever be discharged from one head), for water to be discharged, both heads will need to be activated. As soon as one of the heads operates (device works regardless of which head operates first), a fault signal is sent to a monitoring panel. If there is a real fire then the second head will operate almost simultaneously and water will be released triggering flow-switches and alarm valves in the same way as any other sprinkler head activation. If only one of the heads is activated then no water is released and the fault can be investigated and the Gemini unit replaced if necessary.

Gemini provides a quick, easy and cost effective solution to providing conformity to LPC Rules for Automatic Sprinkler Installations for areas such as server rooms in buildings over 30m high. It is LPCB and VdS approved and is suitable for life safety applications.

For more information about Gemini, please contact Project Fire Products on 01889 271271 or visit www.geminipreaction.info where you can download a brochure and our case studies including Gemini protection installed at Heron Tower (London).

PF Blog

Sprinkler Talk!

Project Fire: Innovators in fire protection, for the most innovative car manufacturers in the world

Modifications as Easy as 1, 2, 3

Zonecheck Addressable: The Future of Fire Sprinkler System Management

TB206: Why You May Need to Sprinkler Protect Your Server Rooms