DOMESTIC SPRINKLER SYSTEM info BS 9251 2021 compliance

Domestic fire sprinkler systems are often required by Building Control or legislation, due to poor fire brigade access, building design and other factors, or simply families choosing to protect themselves from the devastating effects of fire.

We aim to give you a guide of of what to look out for to ensure if you need fire sprinklers, and  that they are installed to the rules (this is all a bit dull, but it is clear and written for anyone to understand- ignore it at your peril)

Each fire sprinkler is activated independantly in a fire usually at 68 degrees centigrade, your house will not become a Hollywood movie scene, the sprinkler system will react locally, one head at a time if they are required.

Town main system or pump and tank?

A domestic dwelling may be able to run off the town main water supply.

If the town main water is acceptable, an automatic priority demand valve will be needed to turn off the household water supply in the event of a fire.

If the water meter is in the road it could be difficult to utilise a town main system with sufficient flow/ pressure.

If your supply is old lead or less than 32mm it's highly unlikely a town main will be acceptable in most cases.

Town houses/ taller buildings will probably not have sufficient dynamic flow rate in the town main supply to run sprinklers at the higher levels in the building. Your contractor is responsible for testing the main prior to any work being carried out, to assess suitability.

At the comissioning stage your house must be on maximum water demand eg a shower and a toilet refilling, with the flow test being carried out. A priority demand valve must be fitted if it doesn't pass.

If it doesn't pass and a PDV is necessary, the test can be repeated with the domestic supply off. This will test if there is enough dynamic flow rate for only the sprinklers.

You will need a fused spur to provide power to the demand valve. The fitting of this valve is in your household supply so it may be your responsibility to fit the valve. A Grifen pdv will failsafe (close on power loss) so the circuit does not need power backup.

It is however imperative that any certificate offered by the installer has checked the operation at full demand and full sprinkler flow. 

Installers can not leave that upto you and they can't issue a certificate either, if it is not done.

Suction lift; Grifen offer pumps that can suck the water from an underground tank, this should generally be avoided as a tank with a positive pressure is preferred. If you have no space, it is an option to have a burried tank, it will add cost. Underground tanks are also category 5 fluids, so the water is in effect effluent.

If the town main water supply is not sufficient there are 2 options

1)Water storage tank and pump. The water tank will typically be 1200 litres or over, if 2 sprinklers are in any one room.

The water supply must last for a minimum of 10 minutes. An infill to the tank is allowed, this can only account for 40% of the required capacity as a maximum. Infills must be proven with a flow test and the infill must have a type AB air gap (a cistern above the main tank) as required by water regulations.

A 10% factor of safety is required as a minimum.

Water tanks must have a low level alarm, although described as low level it should alarm at circa 90% full.

Sprinklers discharge more water at lower building levels (the most favourable area of operation), the tank and pump must be capable of meeting this demand.

Limit your tank size Grifen offer flow controlled pumps- BOOST8n domestic pump which limit your tank size. The calculations should be shown on the design drawings (you MUST be issued with these, please check for remote and favourable area calcs). There is an unscrupulous Nationwide company that will always lead you to believe your main is good enough, if your quote states that, then make sure you witness the flow test before committing, it's very easy to prove one way or another, don't leave it until work has started and then get told- "Oh sorry you need a pump and tank".

It will get suprisingly expensive very quickly and it is avoidable. You may need a tank, that's life, just make sure you know either way before you buy, then you can compare like for like quotes not apples with poison ivy. 

2) Pumping off the main. 

YOU CAN NOT PUMP OFF THE MAIN AND COMPLY!
 

Altough the rules sugegst you can do it, techncially you can not.

If you add a pump you automatically need to caluclate a Qmax, so flow rate required increases dramatically. 

You have to decide if both switches have gone unhelathy and        re-healthy to pass the test. You simply can not achive this with the town main operating. Any pump company suggesting you can needs to be avoided like the plague- they have no idea what they are doing. It is very dangerous, you simply can not risk having a false positive when you have a variable that could pass a test that should fail. 

WRAS approval means nothing, other than components are not going to pollute the main- it infers zero technical compliance.

Weekly pump test Grifen do weekday daily or twice weekly tests as we think it's safer.

Grifen have been performing the BS 9251 2021 test since we began manufactuiring fire sprinkler pumps, you could say it is the Grifen standard.

You will need to employ a fire sprinkler contractor, commercial companies carrying LPCB approval often have a knowledge base way beyond that required by BS 9251 2021.

They should be able to install residential systems as well as domestic and residential companies.

Remember when entering into any commercial agreement it is important to do some due diligence- check the contractor and the directors of the companies previous history, this is very easy to do for free at a basic level on the internet and may save you a big problem.

Photographs of previous installs should help you, pictures of completed houses tell you nothing of what you should expect.

Technical drawings and flow calculations will be carried out by the contractor to BS 9251 2021

Basic maths principle

Domestic fire sprinklers require at least 1/2 bar of pressure to operate.

Building height also adds to the pressure required, each storey being circa 3 metres adds 0.3 bars.

Pipe work friction then adds losses, which must be compensated for.

So for a three storey building you could expect;

0.5bars (sprinkler minimum operating pressure)

+ 0.3 (pressure in bars /floor) x 3 (floors) =0.9 bars 

1.0 bar (frictional loss created by the pipe system itself-varies with pipe size and system complexity)

= 2.4 bars (similar to your car tyre pressure)  at around 100litres per minute.

A flow test will need to be carried out on completion, it is worth witness testing this, you will be given a certificate as evidence.

A test valve will be opened and the flow meter should read the required flow e.g 100litres/ minute, the gauge should read the required pressure during the flow test. e.g 100litres/ minute at 2.4 bars.

This is a simple guide and your fire sprinkler contractor should be able to answer questions specific to your home.

You must be provided with drawings of the system and the name of the installing contractor must be prominently displayed, a cabinet/ spares should be provided.

If any of these are not being provided you should seek further advice.

Power cables to your pump system must be fire rated as should alarm cables, they are usually red or armoured.

It is essential you see this system working and what happens if something has failed or there is a fire.

There are plenty of people who die in fires, make sure your system works, you wouldn't buy a televison with a remote control that doesn't work.

Why buy a sprinkler system that is not complete/ functional.

Each year you will be required to carry out a service, similar to a landlord gas check which will involve a sprinkler head check, flow test etc.

A Service requires a walk round survey of the site according to BS 9251 2021, systems which dispense with annual visits do not comply with BS9251, however rigorous a remote test is claimed to be! There is even an LPCB approved annual flow switch test device, that's all well and good, but it's marketed as not needing a visit- that is against the rules. It is very clear the risk needs to be checked and a functional flow test carried out, testing a flow swith is not the same.

Certificates must clearly state if non compliances / deviations from BS 9251 2021 have been used.  Contractors may put electrical/ alarm/ heating services at the risk of the customer, please ensure if pumps are installed outside/ in lofts, that you either protect them from frost or it is done as part of the system. BS 9251 2021  puts the onus on the sprinkler contractor and all the alarms and fault alarms must be tested by the contractor, telling you that it's "by others" is no longer acceptable! You must never accept it.

You may have to do the work as it is your property, but you can NEVER get a certificate until it is all complete. If you are a landlord your insurance will probably be invalid, if there is a loss, it is totally avoidable so please follow our basic guide.

We have made  a simple precis of BS 9251 2021 and put in laymans terms so you can follow it/ question it and act on it and be safe and insured.

Partial sprinkler systems do not comply with BS 9251 2021!! even if an Authority having jurisdiction allows them (but they don't comply- never, your certificate can't state that it does).

Remote test valve  can now fitted at the pump in BS 9251 2021. It is a poor test and test should be carried out at the remote location. 

All Grifen pumps do allow the test to be perfomed at the pump by pressing and holding a button.

This remote valve is also used to vent air, make sure one is fitted, spraying compressed air at a fire will lead to disaster, it's in the rules.

Many pipe systems won't tolerate compressed air, so you have to vent it.

As the system is filled with water the trapped air gets compressed at the top of the building and in range pipes.

We hope this information will help you install a fire sprinkler system and ensure it is done well.

Of course cost is a consideration but it must be done correctly and that may mean paying a little more.

Domestic sprinkler systems are designed to allow for property escape but they also by their nature protect your valuables and more importantly the family memories.

Fire and fault alarms will form part of the fire sprinkler system.

If a pump is fitted it must be monitored for power failed and weekly test failed.

The alarm must be visible or audible at an obvious location in the house, an audible alarm on a pump doesn't comply, unless you put it in your front room.

A simple fire alarm panel is the easiest way to achieve compliance.

If you have a pump and you ask for it to be switched off, a fault alarm must be seen or heard.

A fire alarm should be raised if there is flow in the sprinkler system (this may take upto 30 seconds to trigger to prevent false alarms). 

It is good to make a plan for escape and teach any children what they should do if they hear the alarm.

Fire alarms and pump cables must be fire rated, of course as you browse our website you'll see the red Fire rated approved cables everywhere.

Power connection

Machinery Equipment directive

This is law and applies to all motor driven devices, ie your sprinkler pump.

The pump is designed to run until destruction when defined as a fire pump unless switched off.

This is a runaway condition and could cause steam which is dangerous.

Some pump systems don't have this feature, if they don't they don't comply with the directive and your system is illegal.

Grifen sprinkler solutions pumps have auto cooling as standard and intelligent interactive cooling too.

Many of our pumps have been saved in accidental starts, we replace many of our competitor pumps that have burnt out due to overheating.  

We can of course provide products that comply for all the above.

You can't get a retrospective certificate from the undertaker, nor will your insurance pay out with a wonky certificate.

Please call us if you have a question.