Drain Valve. Close this valve when the hydrant is open. If
water comes out of the drain or saturates the ground around the hydrant when the
hydrant valve is open, replace the drain valve facing or gasket.
Close the hydrant valve, open the second nozzle, open the hydrant
valve, and flush the hydrant. Record the pressure with the hydrant valve open.
Close the hydrant valve slowly and note the lowering of the water
level in the hydrant after the valve is closed. If the water level does not drop, the main
valve is leaking or the drain valve is plugged.
Hydrant-Flow Tests. Conduct hydrant-flow testing in accordance with the
latest edition of the publications listed in pars. 2.2.47 and 2.2.60.
During flow tests, the hydrant nozzle needs to be unobstructed, so the
only way of protecting property is to choose the nozzle that will do the least damage.
Provide barricades to divert traffic and take any other precautions necessary to
minimize property damage and prevent personal injury.
Additional references include those listed in pars. 2.1.4, 2.2.11, and
Hydrant Flushing. Water flow rates required for flushing water mains is
given in par. 2.1.4. Before beginning the flushing, plan to divert flushing flow to prevent
property damage. Use flow diffusers or a length of fire hose where necessary to direct
the flow into a gutter or drainage ditch. A rigid pipe connected to a hydrant outlet and
turned at an angle to divert flow down a gutter is not considered a good idea. The
torque produced by the angular flow could be enough to twist or otherwise damage the
Hydrant Safety. In addition to the general safety precautions detailed in
par. 2.2.2, special precautions must be taken to prevent injury and damage to private
property during hydrant flushing. Following are several special safety concerns:
Besides getting people wet, the force and volume of water from a
full hydrant stream are sufficient to seriously injure workers or pedestrians.
If traffic is not adequately controlled, drivers trying to avoid a
hydrant stream might stop quickly or swerve. An accident might result.
If the temperature is below freezing, water that is allowed to flow
onto pavement may freeze and cause accidents.