jkampana
Mechanical
- Aug 2, 2011
- 45
I am running into some issues on a somewhat unique design for an apartment complex in SLC. Due to the close proximity of adjacent buildings in the area. The builder cannot provide FD access within 150' of all portions of the structure per the IFC. The AHJ has requested, as an alternate means of fire protection, that the design densities in the fire suppression system to be increased a level. Therefore, parking areas will be designed with a .2 design density and residential areas with a .15 design density.
This is not so much of an issue in the parking garage but it is in the apartment areas. The contractor is requesting concealed flat plate pendents in all areas. with a residential head I will have a 4.9 k-factor head of a 5.6 factor head from Reliable. If I use a 16x16 spacing my end head pressure will be (.15*256/4.9)^2=61.41 psi or (.15*256/5.6)^2=47.02 psi respectively. Along with highest outlets being at 50' above the flow test point, adding an additional 21.65 psi to the required pressure for the system. That is even before I start adding friction loss in the pipe so I'm sure you can see my dilemma. A simulated fire flow for the area was 106 Static and 20 psi @ 3000 gpm. I will know the actual numbers next week.
Our hope is to do all residential areas in CPVC and to obviously keep pipe sizes as small as possible. My question is what are some design ideas that I may use to achieve the best and cheapest design possible? I thought about using a commercial head instead of a residential head. That way I can use a most demanding room design approach which would still have me calculating 4 heads in a unit (+2 in coordinator). This would allow me to avoid flowing 4 sprinklers on one branch line and would instead push me to where each compartment has a max of 2 heads on a single branch line. Higher k factors would also help the end head pressure.
I also thought about looping each floor using another standpipe, that would add another floor control assembly for each floor.
Does anybody have any other ideas I may be overlooking or any advice for me on this kind of design? Thanks
This is not so much of an issue in the parking garage but it is in the apartment areas. The contractor is requesting concealed flat plate pendents in all areas. with a residential head I will have a 4.9 k-factor head of a 5.6 factor head from Reliable. If I use a 16x16 spacing my end head pressure will be (.15*256/4.9)^2=61.41 psi or (.15*256/5.6)^2=47.02 psi respectively. Along with highest outlets being at 50' above the flow test point, adding an additional 21.65 psi to the required pressure for the system. That is even before I start adding friction loss in the pipe so I'm sure you can see my dilemma. A simulated fire flow for the area was 106 Static and 20 psi @ 3000 gpm. I will know the actual numbers next week.
Our hope is to do all residential areas in CPVC and to obviously keep pipe sizes as small as possible. My question is what are some design ideas that I may use to achieve the best and cheapest design possible? I thought about using a commercial head instead of a residential head. That way I can use a most demanding room design approach which would still have me calculating 4 heads in a unit (+2 in coordinator). This would allow me to avoid flowing 4 sprinklers on one branch line and would instead push me to where each compartment has a max of 2 heads on a single branch line. Higher k factors would also help the end head pressure.
I also thought about looping each floor using another standpipe, that would add another floor control assembly for each floor.
Does anybody have any other ideas I may be overlooking or any advice for me on this kind of design? Thanks
