Why Fire Flow Testing is Vital for Community Safety

Vital for Community Safety


Fire Flow testing provides actual pressure and fire flow data measured at specific fire hydrants (FH) within the water system. City planners and sprinkler design companies use this information. Flow tests also help detect closed valves and other mechanical problems that could delay the construction process or cause significant change orders later in the project.

Emergency Response

Often, hydrant flow testing will uncover mechanical problems ranging from valves that don’t operate to pump-damaging debris in the water mains. Discovering and fixing these issues ensures hydrants perform as intended during an emergency. The information derived from fire flow testing also provides vital data for sprinkler system design. Many engineers and designers assume that they can use the normal operating pressure of a hydrant (static pressure) when designing a sprinkler system. Unfortunately, this information does not accurately reflect what a fire hydrant can deliver during an emergency. When a flow test is conducted, it increases the demand for the water main, stirring up rust, scale, and sediment that has built up over time. It is common to experience a temporary reduction in water quality after the flow test occurs. This issue can be remedied by running water for several minutes after completing the test.

Water Supply

Besides ensuring water pressures and flow rates are sufficient for firefighting, hydrant flow tests can uncover blockages or infrastructure problems within the system. For example, if the residual pressure reading of a tested hydrant drops significantly after the test is completed, it could indicate a closed valve has prevented the hydrant from receiving an adequate supply of water. To conduct a hydrant flow test, field personnel place a pressure gauge on hydrant #1 (the residual hydrant) and use a pitot gauge to take readings at the two hydrants allowed to flow (hydrants #2 and #3). Slowly opening each of these hydrants provides for a steady flow rate to occur. After the flow hydrant is shut off, the field technician takes a static pressure reading again and closes the gate valve on the hydrant to prevent water hammer. Firefighters use this data to mark hydrants as having “good flow” (“green”), “average flow” (“yellow”), or “inadequate” (“red”). The color-coding system also helps design fire sprinkler systems for commercial and residential buildings.

Fire Suppression

Fire alarms and smoke detectors help protect occupants promptly by alerting them to the danger. The addition of fire sprinkler systems can also help prevent property damage and limit loss of life by suppressing or extinguishing the fire before it spreads throughout the building. Many fire suppression systems can be installed to custom-fit your space. These include water-based systems, clean agents, and, until recently, the use of Halon (which caused severe damage to the ozone layer) gas-based systems. Flow tests provide pressure and flow data for specific fire hydrants on the County’s water distribution system. This data is used to design fire sprinkler systems and is adjusted based on water system conditions. The Fire Hydrant Capacity Flow Test is the only test that accurately predicts the value of the water supply at the hydrant nozzle where firefighters are going to connect their suction hose.

Public Health

Fire Flow Testing provides accurate water data to help plan and mark fire hydrants. The data also assists with water system engineering while designing municipal and privately owned buildings. The test identifies underground fire mains’ pressure and flow-producing capabilities by measuring the difference between static and residual pressure at two nearby fire hydrants (FH). This information is used to assess the performance of the entire fire protection system. The “test” FH is slowly opened, the pressure at the “flow” FH is measured, and then the difference between the two is compared.

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