SprinklerDesigner2
Mechanical
- Nov 30, 2006
- 1,251
Several years ago Stookey provided me a contact but it appears their contact info is no longer valid. That said I understand the need to engage the services of a Georgia FPE or or knowledgeable PE to help me address this problem and I am looking for one.
There are two separate issues I am dealing with; one involving amendments to NFPA #13 and the other amendments to NFPA #20.
CHAPTER 120-3-3 RULES AND REGULATIONS FOR THE STATE MINIMUM FIRE SAFETY STANDARDS
First having to do with modifications to NFPA #13 beginning on page 27 with the meat of the issue on page 29:
NFPA #20 beginning on page 33
I didn't see any problems coming on this job. I can appreciate the water supply is marginal but that is what fire pumps are made for with the understanding fire pumps don't make water but boost pressure.
Flow test results 45 psi static, 27 psi residual with a flow of 628 gpm.
Addressing the minimum 20 psi suction with pump operating at 150% know I got it as demonstrated here:
Calculation from source to pump suction flange at 150 percent of pump rated flow
Calculations showing a minimum 10 psi safety cushion
Calculations demonstrating a minimum 10 psi cushion is available
I talked with the local authority having jurisdiction about the exceptions and even though I do not believe I need either of the exceptions available it would help a lot with local official granting the exceptions if they can be convinced the system is fully adequate.
There are two separate issues I am dealing with; one involving amendments to NFPA #13 and the other amendments to NFPA #20.
CHAPTER 120-3-3 RULES AND REGULATIONS FOR THE STATE MINIMUM FIRE SAFETY STANDARDS
First having to do with modifications to NFPA #13 beginning on page 27 with the meat of the issue on page 29:
(8) NFPA 13, 2002 Edition,
Standard for the Installation of Sprinkler Systems
Modifications:
snip
3. Add a new subsection 14.4.4.8.3 to read as follows:
“14.4.4.8.3 There shall be a minimum 10 psi (0.69 bar) cushion between the hydraulically
calculated sprinkler system demand and supply when there is a backflow prevention device present.
“Exception: 10 psi (0.69 bar) cushion may be lowered with permission of the authority having
jurisdiction.”
NFPA #20 beginning on page 33
(18) NFPA 20, 2003 Edition,
Standard for the Installation of Stationary Pumps for Fire
Protection
Modifications:
(a) Modification to Chapter 2:
1. Add a new paragraph 2-1.1.1 to read as follows:
“2-1.1.1
At 150% rated capacity or below, the pump suction supply shall not drop below 20 psi
(1.38 bar).
Exception: Suction supply pressure may be lowered upon approval of the authority having jurisdiction.”
I didn't see any problems coming on this job. I can appreciate the water supply is marginal but that is what fire pumps are made for with the understanding fire pumps don't make water but boost pressure.
Flow test results 45 psi static, 27 psi residual with a flow of 628 gpm.
Addressing the minimum 20 psi suction with pump operating at 150% know I got it as demonstrated here:
Calculation from source to pump suction flange at 150 percent of pump rated flow
Calculations showing a minimum 10 psi safety cushion
Calculations demonstrating a minimum 10 psi cushion is available
I talked with the local authority having jurisdiction about the exceptions and even though I do not believe I need either of the exceptions available it would help a lot with local official granting the exceptions if they can be convinced the system is fully adequate.