The first part of the inspection process is a general visual
observation making sure the valve is installed correctly,
checking for signs of damage due to past winter weather,
and checking the plumbing serving the valve for leaks.
You would probably be surprised how many connections
like the ones below are found every season. These leaking
connections must be found and repaired. If a backflow
condition occurred, the water from these leaks would
drain back into the water service and water main.
After determining all connections are in order,
a differential test kit is then connected to the test ports.
These test ports are located in a manner that will allow the
tester to register the pressure on both sides of the check
valves and report the difference in pressure, and also allow
the tester to check the relief valve and make sure that it
opens if the water pressure drops.
The relief valve is the most beneficial part of the R.P.Z.
In the event of a pressure loss, the relief valve opens and
effectively breaks the connection keeping any unsafe
water from entering the potable water supply. An R.P.Z.
that is working properly will keep 100% of questionable
water out of the water supply 100% of the time.
In the photo below are the two most
common
R.P.Z.s used in our local area, a Watts 009 &
a Febco 825.
As you can see, springs, washers, and o rings abound.
These parts are under a constant work load, adjusting
for fluctuating pressure in the service mains. Springs
become weak, washers were out, and o rings become
damaged.
The test procedures used to inspect an RPZ
will detect if any of the many internal parts
are functioning improperly, or if any other
general maintenance is required.
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