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The following is a very brief summary of a typical installation in a domestic property. Pipe sizes may differ from a system for a residential sprinkler solution, however the process will be similar to this:
Domestic and Residential Fire sprinkler systems are dependent upon reasonable pressures and comparatively large flow quantities. To maximize the available pressure and flow we need to keep the frictional losses down to a minimum by utilizing as few bends as possible and by ensuring the pipe work is sized correctly. To achieve this we are very careful at the design stage and always use ‘Blazemaster’ pipework which has a very low coefficient of friction.
Designing the System:
The design work is generally carried out in CAD form and the dynamic pressure requirement for the system is calculated. It is obviously important to establish that this pressure at the designed flow rate will be available from the mains water supply. The water undertaker will be consulted and If not, a storage based system will be recommended and a suitable pump will be sized accordingly.
Our pipe work is installed at the same stage as any electrical and plumbing 1st fix process. We try to find as direct a route as possible to the top of the property for our riser from the incoming main or pumped supply (if this is on the ground floor).
The external diameter of pipework is generally 35mm-42mm for the riser and 28mm-35mm for horizontal pipe runs.
If pipework travels at right angles to joist work, each joist will be drilled on the centre line of the joist at a point between 0.25 to 0.4 of the joist length wherever possible. Modern TJI and eco-joists facilitate the installation process considerably.
Pendant fire sprinkler heads are ideally positioned in the centre of the ceiling however if there is a conflict with a pendant light it can be off-set provided that the distance from the sprinkler head to the wall is within the manufacturers recommended coverage. It is generally accepted that a normal pendant light fitting will not obscure the spray pattern of a fire sprinkler head once activated. Larger fixed ceiling mounted items can cause a problem and it is important that the system designer is informed of any projections below the ceiling level like fluorescent lights and structural beams
Side wall sprinkler heads are not used as frequently as pendant heads partly because they make a greater demand on the available water supply. The coverage can also be obscured by large pieces of furniture placed near them.
We will always obtain the electrical drawings for the project and use these in our design in order to ensure that there is no conflict between the sprinkler head positions and light positions. In the case of down lights, we will ensure that the fire sprinkler heads are symmetrical with the electrical design wherever possible. Scaled drawings are always issued to our customers for approval prior to commencement of 1st fix.
These will normally be installed at 1st fix stage. It is important to install loft tanks as early as possible due to their size – ideally when the roof trusses are set in place.
Once the pipework is in position, the sprinkler heads are connected and yellow temporary plastic covers are left in place for protection during the continuing build process. There is only a very small amount of adjustment available for the fire sprinkler heads so it is very important that we are told what the overall thickness of the ceiling finish will be.
The system can now be pressure tested and left at pressure until we are called back at 2nd fix stage.
The plastic covers which protect the sprinkler heads project below the ceiling level which ensures that the plaster board is cut around the heads when fitted. The plasterer then plasters up to the covers and the decorator can paint up to them as well.
The 2nd fix process is relatively straight forward. The plastic caps are removed and pre-finished cover plates are installed which cover the ragged edge left by the caps. If we are supplying a fire alarm and/or a pump, these will be installed at this stage.
Checks and Testing:
This will often be carried out at the 2nd fix stage. Our engineers will go through a series of checks and once the appropriate labeling etc is in place the system will be equivalence tested in order to ensure that the fire sprinkler system will perform adequately if required.