Canute LLP

The design of domestic and residential sprinkler systems to standards such as BS 9251, NFPA 13R and 13D require you to design the systems with 1, 2 or 4 sprinklers in operation. 

 

For instance a BS 9251 sprinkler system for a domestic occupancy would require you proved calculations for 2-sprinkler in operation with a minimum flow of 42 l/min/sprinkler and 1 sprinkler in operation with a minimum flow of 60 l/min.  When the FHC program calculates a project the minimum head flow is calculated on the minimum head pressure or the design density (which ever is the greater). Therefore if you require a flow rate from a sprinkler head you can increase the minimum head pressure or specify a design density.

Example 1

If we require 60 l/min from a sprinkler head and that head is protecting an area of 9m2 then the design density required would be 6.7 mm/min.

Open the FHC project required [Ctrl+O] and then use the edit command on the pipe [Ctrl+E]. Enter 9m2 as the head area and then enter 6.7 mm/min as the head density. Apply the changes and then close the Edit window.

Now Calculate the signal sprinkler head.

Example 2

If we require 60 l/min from a sprinkler head, which has a k-factor of 57, calculate the minimum required pressure.

Open the project data [Ctrl+P] and go to head data and add a new head code. We can now use the standard sprinkler head formula q=k.p^0.5. If the sprinkler has a k-factor of 57 then p=(q/k)^2 = 1.11 bar. This pressure should then be used as the minimum head pressure.

Now Calculate the signal sprinkler head.