Flow tests measure how much water a hydrant can deliver. You record them from the hydrant's detail page.

Step by step

  1. Open the hydrant's detail page.
  2. Make sure the Flow Tests tab is selected (it is selected by default).
  3. Click Add Flow Test above the table.
  4. A form opens with several sections. Fill them in as described below.
  5. Click Submit when you are done.

Test details

  • Test Date -- The date you performed the test. Defaults to today.
  • Technician -- The person who ran the test. Defaults to you. You can search for another user if someone else did the work.

Test port

If the hydrant has connection types already entered, a Hydrant Port dropdown appears. Pick the port you opened for the test and the outlet diameter fills in automatically. If the port is not listed, or if the hydrant has no connections on file, type the outlet diameter into the Outlet Diameter (inches) field (common sizes are 2.5", 4", and 4.5").

Next, set the Outlet Type. This affects the discharge coefficient used in the flow calculation:

  • Smooth / Rounded (c = 0.9) -- The most common type.
  • Square Edge (c = 0.8)
  • Projecting / Rough (c = 0.7)

Pressure readings

  • Static Pressure (PSI) -- The pressure with no water flowing. Attach a gauge to a cap and read it before opening the test port.
  • Residual Pressure (PSI) -- The pressure while water is flowing from the test port. Read the gauge while the port is open.
  • Pitot Reading (PSI) -- The pressure at the center of the flowing stream, measured with a pitot gauge at the outlet opening.

Flow results

As you enter pressure readings, three values calculate in real time:

  • Calculated Flowing GPM -- The gallons per minute of water flowing from the test port.
  • Rated Capacity at 20 PSI -- The estimated GPM the hydrant could deliver if residual pressure dropped to 20 PSI.
  • NFPA 291 Classification -- A color-coded class based on the rated capacity (see the Understanding flow test results article).

Manual GPM override

If you used a device like a Hose Monster that gives you a direct GPM reading, turn on the Override with manual GPM reading (e.g. Hose Monster) toggle. A Manual GPM Reading field appears where you enter the GPM value. The system will use your number instead of the calculated value for the rated capacity and classification.

Residual pressure warning

If the residual pressure drops below 20 PSI, a warning message appears. This means the water supply may not be strong enough to support firefighting operations at that location. Record the test as normal, but flag the hydrant for follow-up.

Notes

Use the notes field for anything that affected the test, such as "tested during peak demand hours" or "nearby construction may have reduced pressure."

Tip

Always record the outlet type carefully. The difference between a smooth and a projecting outlet changes the calculated flow by about 22%, which can move a hydrant from one NFPA class to another.