Booster Pump

[sia101]

Hi,
I am worrking on a fire sprinkler design on a new shopping mall bordering 2 streets, one on east side one on west side. There are 4 separate 4 story retail structures above 60,000sf common shopping mall. They share common address. One of the 4 structures is open parking structure. The roof top of the parking structure is used to park cars and is considered a level and I was required to design a Class II Fire Hose system 65 psi @ 100 GPM. in addition to 5-Class I Standpipes for parking structure and other Buildings.
Structures have passed building plan check and they are
not classified highrise. The city water pressure at street
level is 90 psi.
Here, I am going back and forth before sizing a fire pump to deliver 65 psi at the Class II Fire Hose Cabinet.
System components(ex. Fire Sprinkler Heads)rating is
at 175 psi if I am correct and have to make a resonable judgement not to exceed this pressure if I am also correct
as over rated system components are special order. Besides, I have no idea what additional measures will be required to over reared sprinkler systems. If I select a fire pump say 85 psi@750gpm, am I going to be on a safe side, seriously?
any experienced comments?
nathan

 

[TravisMack]

You have 90 psi at the street. If you select an 85 psi pump, that will likely churn around 100 psi. Therefore, you will have 190 psi sitting on the system at all times.

If you are not a highrise, can you have your standpipes be a manual wet? That would save you the pump?

If you must have a fire pump, you will need to check your pump curves and see what you have at churn, but you are probably looking at 70 psi max for a pump. That is assuming 120% at churn.