Sprinklers to High Rise Residential

[Jon Barrett]

I am aware of BS9251 for residential sprinklers however the application of this is limited to residential occupancies 'not exceeding 20m'.

Does anyone know what standard is worked to for residential sprinklers for buildings higher than 20m?

Any assistance would be appreciated.

Thanks,

Jon

[wee brian]

In theory you should be using BS 5306 or its EN replacement (cant remember the number)

In practice people often use 9251 as there is no real logic in the 20m limit

[ian gough]

En 12845

[John Webb]

I suspect the limit in BS9251 may be there because there may be insufficient pressure in domestic mains to provide sufficient flow through a system above 20m, where the static head has to be overcome. In BS5306 the water supply requirements are more stringent and require allowances to be made for larger static heads.

[wee brian]

Nope

9251 sets flow and pressure requirements at the head. So you put whatever pump you need in the system. With UK water supplies being what they are you will often need pumps well below the 20m threshold

[Jon Barrett]

Thanks for your responses.

The new draft Part B further confuses things because it states that.... 'apartment buildings with a floor more than 30m above ground level should be fitted throughout with a sprinkler system in accordance with BS9251'.

Some respondents to this version of Part B identified that 'BS9251 limits its scope to buildings up to 20m in height with the effect that a conventional (commercial) type sprinkler system should be used above this height'. Presumably they mean that it should be designed to 5306/12845.

9251 states... ‘where buildings exceed 20m in height, special circumstances need to be considered and the authority having jurisdiction should be consulted. This matter is receiving the attention of the relevant BSI committee with a view to issuing an amendment’.

1 -------- Does anyone know whether the BSI have got anywhere with this?

9251 does show schematics with pumps installed. So the 20m doesn't appear to tie in with the limit of available mains pressures. 9251 requires the pipework to be hydraulically calculated.

2 -------- On this basis would it be reasonable to suggest that a system could be designed in line with 9251 flow and pressure requirements and broken into vertical zones (up to a maximum of 45m per vertical zone, as per BS5306) and fitted with a multi-stage pump where the building is over 45m in height?

Further comments would be appreciated.

[Jon Barrett]

For those inteested...

The 2006 ADB (just out) now states that 'Blocks of flats with a floor more than 30m above ground level should be fitted with sprinklers... for the purposes of this paragraph the limit on the scope of BS9251 to buildings below 20m can be ignored'.

No clarification is given as to how BS9251 is to be applied to a building over 30m i.e. what additional measures are required - I suspect the design will need to be designed along the lines of BS5306 but with the pressure and flow requirements of BS9251 - a zoned installation.