Flow test data provides necessary field information so that water department planners and the fire department can accurately estimate the capabilities of water mains. Water main and hydrant flow capabilities impact decisions as to what fire protection and fire resistance features are required for new developments and where priorities should be placed with respect to upgrading older, smaller water mains. Another important reason for flow testing, flushing, and inspections is that having these functions performed on a regular basis can help to lower your ISO rating. Testing and inspections will also help to lower your possible liability risk.
Regular hydrant flow testing is a significant component of a water supply program. Water systems are constantly being impacted by improvements, deterioration, changes in usage, and even water department maintenance activities which may affect zone valve settings. As a result it is important to annually test all fire hydrants to determine what their capabilities would be in an emergency.
At this point, the flow test is initiated. We assign a rating of AA, A, B, or C gallons per minute to each hydrant. Included in the flow testing are:
Gallons per minute at hose nozzle
Gallons per minute at pumper nozzle
Main size diameter
Date and time of inspection
The inspection continues with a check for leaks in the following areas:
Operating nut (o-rings)
Bonnet and bonnet gasket
Hose caps and gaskets
Pumper cap and gasket
Upper stem and lower stem
Flange and flange gasket
Underground leaks such as drain facings, main valve, etc.
In summary, there are 2 main reasons for flow testing fire hydrants:
1. TO DETERMINE HOW MUCH WATER IS AVAILABLE FOR
2. TO DETERMINE THE GENERAL CONDITION OF THE
Fire hydrant safety issues are best detected during inspection and before an emergency. While inspecting we:
Find "OUT OF SERVICE" hydrants
Locate main valve leaks
Notate seized pumper and hose caps
Exercise the operating nut to ensure the hydrant will pressurize
Find broken couplings which would keep the hydrant from pressurizing