Fire Flow Test

Overview

The tests provide actual pressure and flow data measured at specific fire hydrants (FH) within the County’s water distribution system. This data is used in assessing the pressure and flow available for fire protection and in sprinkler system design to ensure public safety.

• The “test” FH is typically the hydrant closest to the subject property’s connection point to the County’s water system.
• The static pressure is the system pressure measured at the “test” FH under normal flow conditions
• The “flow” FH is typically an adjacent FH located on or near the same water main as the “test” FH.
• The “flow” FH is slowly opened and the amount of flow at the “flow” FH is measured while the residual pressure at the “test” FH is measured.
• The difference between the static and residual pressures measured at the “test” FH indicates the drop in pressure that occurs when the measured flow is imposed on the system.

Sprinkler designers utilize the static and residual pressures and the measured flow recorded during a fire flow test to design the sprinkler system for the subject property. Proposed sprinkler system designs are reviewed by the fire protection engineers in the Permit Center. The sprinkler system design must be approved by the engineers at the Permit Center before a building permit can be issued. Inspections must be done by the Fire Marshall’s Office before the building occupancy is permitted. This review process ensures that sprinkler systems are properly designed and that adequate fire protection is available to ensure public safety.