Fire Sprinkler System Installation
Residential Fire Sprinkler Systems are dependent upon reasonable pressures and comparatively large water flow quantities. Frictional losses within the sprinkler system need to be kept down to a minimum in order to maximize the available pressure and flow available from the town main or the storage system whichever is used. This is achieved by incorporating as few bends as possible and ensuring the pipe work is sized correctly.
In addition to this, we always use ‘Blazemaster’ pipework which has a very low coefficient of friction compared for example with iron pipe which has a very irregular internal surface.
Designing the System
Design work is always produced from AutoCAD drawings supplied by the customer and the calculation of dynamic pressure requirements for the system are produced from a software package. It is important to establish that the required pressure at the designed flow rate will be available from the mains water supply. If the available pressure/flow is not available from the town main. a storage system will be recommended and designed into the system accordingly.
Sprinkler Head Positioning During the Design Process
The optimum position for Pendant fire sprinkler heads is in the centre of the ceiling. However, as more and more down lights are installed within properties, there is a greater demand for the sprinkler heads to line up with as many ceiling fittings as possible. Our designers have considerable experience of lining the sprinkler heads with other ceiling mounted items while ensuring that the head is positioned within its design limitations.
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.
When the Pipe Work is Installed
Our pipe work is installed at the same stage as any electrical and plumbing 1st fix process. We try to find the most direct 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.
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 refer to 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.
Protection of Sprinklers During Construction
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 a only a very small amount of adjustment available for the fire sprinkler heads so it is 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.
Plastic Covers removed
The plastic covers which protect the sprinkler heads project below the ceiling level to ensures 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.
Installation of Pre-finished Cover Plates
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
Usually carried out at the 2nd fix stage. Our engineers will go through a series of checks and once the appropriate labelling etc is in place the system will be equivalence tested in order to ensure that the fire sprinkler system will perform adequately if required.