HomeMy WebLinkAboutB10-0026 Nagle Residence FP Hydraulic Analysis Letter
7026 South Tucson Way Centennial, Colorado 80112 303-792-0022 303-792-9049 Fax Fire Protection Systems Design Fabrications Installation Commercial Industrial Residential Institutional
Special Hazards High Tech Defense Hangars Retrofit Service Inspection Maintenance August 24, 2011 Mr. Mike Vaughan Town of Vail Fire Department Vail, CO 81657 RE: Nagle Residence
Fire Sprinkler Hydraulic Demand Analysis Mr. Vaughan, Based on the site survey and basic hydraulic calculations performed by Western States Fire Protection, we have determined that the
existing water supply for the above named property is not sufficient for providing enough pressure to properly operate a fire sprinkler system in accordance with NFPA Standards. The
narrative below summarizes our survey, calculation procedures and results. During the site survey we determined that there is approximately 120ft of ¾” copper piping running underground
from the water entry inside the house to the underground isolation valve. We also determined that the static pressure in the house is 115psi. We assumed a system flow demand of 26.4gpm.
The flow demand was based on discharging 2 sprinklers (4.9K) at the minimum required pressure of 7psi (12gpm each) plus an additional 2.4gpm (10% of combined sprinkler flow for overflow).
We determined that if the ¾” underground copper is Type K (worst-case), the internal diameter would be 0.745”. The friction loss through a foot of ¾” Type K copper pipe flowing 26.4
gpm with a C-value of 150 would be 0.762psi (Hazen-Williams). We then multiplied the pressure loss per foot by the 120ft of underground piping which resulted in a total pressure loss
of 91.44psi. If we also take into account the pressure loss from elevation (approximately 30ft) we add another 13psi to the total pressure loss (now 104.44psi). We can also add another
7psi loss to discharge the remote sprinkler (now 111.44psi). This leaves only 3.6psi left from the available 115psi. In summary, we have determined that the pressure required to deliver
adequate flow for a residential fire sprinkler system cannot be achieved through the existing water supply. Please let me know if you have any questions. Sincerely, Western States Fire
Protection Brian Houser AUG 2 4 2011 Project Manager