Fire Flow Testing Hydrants
Fire flow tests are conducted on hydrants to determine water availability in planning for firefighting activities, fire sprinkler systems or domestic water demand. The tests are also useful in determining the general condition of the water distribution system by detecting closed valves or wall deposits. A well-maintained water system enables firefighters to extinguish flames and prevent large- scale damage or loss of life.
How often do I perform Fire Flow Tests on hydrants?
- AWWA recommends flow testing all areas at least every 10 years. (AWWA M17).
- NFPA requires flow testing of underground and exposed piping at least once every 5 years (NFPA 25, 7.3.1, 2008).
Where do I find more information on fire flow testing?
- NFPA 291 — Recommended practice for fire flow testing and marking of hydrants
- AWWA Manual 17 — Installation, field testing, and maintenance of fire hydrants
- Hydro Flow Products Catalog — Section on Fire Flow Testing includes how-to instructions and more
- Fire Flow Test Calculator — Calculates the rated capacity at 20 psi for a fire flow test.
- FAQs on Fire Flow Testing
What equipment do I need for Fire Flow Testing?
1. Hose Monster®
- BigBoy Hose Monster (HMBB4) — 750 to 2700 GPM. Lightweight, enables flow from hydrant pumper port and displays GPM flow-rate on gauge face.
- Little Hose Monster™ (HML) — 1500 GPM or less. Small, lightweight and pitotless (no pitot damage from flushing debris).
2. 2" Pitotless Nozzle™ (PN2GRV, PN2THD) — For use with the Little Hose Monster (use PN2GRV) or the 2 1⁄2" Hose Monster (use PN2THD). It measures from about 500 –1500 GPM and is the most common size for hydrant fire flow testing.
3. Discharge Flow-rate Gauge (Gauges) — 60- and 100-psi gauges are common. Anticipate pressure ranges within your distribution system so readings are in the middle third of the dial.
4. Remote Reader (Remote Readers) — Enables you to take gauge readings at a convenient distance from discharge. Sold in three lengths, the 12' length is usually sufficient for fire flow testing.
5. Test Hose (Hose) — Length: For fire flow testing, 5' or 10' lengths are most common. Options for attaching a hose to a hydrant: – Attach a 21⁄2"-diameter hose to the pumper port by using a reducer. This is our preferred option because it enables a Little Hose Monster™ or 21⁄2" Hose Monster® to be used from the pumper port and usually positions discharge directly in street gutter.
- Attach a 2 1⁄2"-diameter hose to the nozzle port of the hydrant. The hydrant nozzle ports are usually located on the sides of the hydrant and parallel to the street. A 10' hose with a slight arc out of the nozzle port should discharge water in a street gutter.
- Attach a 4" or 4 1⁄2" hose to the pumper port of the hydrant. The pumper port of a hydrant is usually positioned so a 5' hose out of the pumper port should position discharge directly in street gutter. This is usually used with a BigBoy Hose Monster or 41⁄2" Hose Monster, but can be used with the HML and HM2H if a reducer is attached to the end of the hose.
6. Hydrant Gate Valve (HGV25, HGV4, HGV45) — This enables greater control of the water flow and reduces stress and opportunities for water hammer when opening or closing hydrants.
7. Gauge Cap (GCSW) — This component collects static and residual pressure readings from a hydrant in a fire flow test. It attaches to the 21⁄2" NST nozzle port on the residual hydrant.
8. Static/Residual Pressure Gauges (Gauges) — 100- or 160-psi gauges are most common. Anticipate pressure ranges within your distribution system so readings are in the middle third of the dial.
9. Hydrant Wrench (HW107) — Enables you to unscrew caps and open a hydrant to flow water.
10. Spanner Wrench (WSPA101) — Attaches a hose to a hydrant or Pitotless Nozzle™
11. Dechlor Demon™ (DD2H, DD4, DD4H) — Designed for dechlorinating discharge water while flow testing without affecting flow-rate measurements. Contact your local authority having jurisdiction for more information when dealing with super-chlorinated water mains or discharging near lakes or rivers.
12. Reducer Adapter (AD4.25, AD45.25) — Enables a 21⁄2" hose to be flowed from the pumper port of a hydrant so that a Little Hose Monster or a 21⁄2" Hose Monster can be used. Adapters for flowing from a Storz also available.
13. Gauge Case (Cases) — Foam- padded cases keep gauges and Pitotless Nozzles protected and prevent damage.
14. Gauge Calibration (GCC2H, GCC4) — For fire flow testing, NFPA recommends test gauges be calibrated within 12 months prior to the test. We offer gauge calibration for new and used gauges that ensures accuracy. It comes with a NIST certificate.
15. Stream Shaper (SS1) — For high-pressure flow-rates, used to prevent hose burn.
16. 45° or 30° Test Header Elbow (Elbows) — Enables the hose to be angled differently and positions the discharge water in a different area.
Flow Hydrant — The hydrant that flows water and measures the test flow-rate.
Hydrant Capacity Test — A type of fire flow test that evaluates the water supply available from the hydrant.
Main Capacity Test — A type of fire flow test that evaluates the water supply of the fire main at the location of the residual hydrant.
Nozzle Pressure — The pressure measured at a nozzle in a fire flow or fire pump test. It can describe the Pitotless Nozzle, hydrant nozzle or the orifice on the Hose Monster. Nozzle pressure, pitot pressure and velocity pressure are often used interchangeably.
Rated Capacity — The water supply available at a specified residual pressure (usually 20 psi).
Residual Hydrant — Also known as Test Hydrant. In a fire flow test, this hydrant measures static and residual pressures. Test results apply to this hydrant.
Residual Pressure — The pressure residing in the water distribution system when flowing in a fire flow test or any other actual flowing condition.
Static Pressure — Water distribution system pressure at zero test flow.
Test Flow-rate — The flow-rate of water that is discharged in a fire flow or fire pump test.
Test Hydrant — Also known as Residual Hydrant. In a fire flow test, this hydrant measures static and residual pressures. Test results apply to this hydrant.
- Hydrant Flow Testing - PM Engineer
- How to Calculate Rated Capacity at 20 psi
- Comparing Hydrant Flow Test Results