Some time after that and prior to the home being sold the assembly began to vent water. Most likely the builder, in his infinite wisdom, had a carpenter fix it. The odds are the technician damaged the piston O-ring upon reassembly causing water to flow through the relief valve stem vent. The technician rectified the problem by plugging the relief valve stem vent with a screw. The technician also failed to reinstall the relief valve spring. As a result he succeeded in making sure the relief valve would never open again.
This is just one reason why we test the backflow assemblies annually. Aside from failures due to normal wear and tear, there are folks out there who think they are doing the right thing by modifying an assembly in an attempt to repair it. These modifications reduced a high hazard protection backflow assembly, to a low hazard device, and of course this is not allowed.
This is a new installation of an 8” Colt 300BF with a ¾” Ames 2000BM3 detector assembly.
If you look closely you will see the upstream side of the ¾” Ames 2000BM3 is connected to shut off valve #2, and the downstream side is connected to shut off valve #1. The detector meter itself is connected correctly with the direction of flow arrow pointing up. However with the way this is set up the detector meter can only run backwards.
This is an improper installation which has created an unprotected cross connection.
Click photo to enlarge
Here we have a very old 3” Beeco C6 Reduced Pressure Backflow Assembly on a domestic water line. Everything is still working like new, the test values are very very good and the shut off valves still close tight.
All this and this backflow assembly is on a cast iron plumbing system. It would not surprise me if this backflow preventer lasted another 10+ years.
Here we have a 1.5” Febco 850 as you can see the disk retainer screws for both checks have come loose and flowed downstream.
I am told the cone shaped object circled in yellow is a fix Febco designed that goes in front of the model 850/860 first check module. Its purpose is to help reduce the vibration that causes the disk retainer screws to come loose.
Click to Enlarge
This is an improper installation of a Wilkins 975XL RPBA installed below ground on an irrigation system. This is not allowed because if check valve #1 should fail the relief valve will vent filling the box and covering the backflow prevention assembly with water creating an unprotected indirect cross connection.
Upon completion of testing the backflow preventer you must check (Improper Installation) and note it in the remarks.
Click to enlarge
This is an approved ½” Air Gap set up supplying water to radioactive equipment. When there is a demand for water; the pump on the lower left will start; water in the storage vessel will drop; the float will open the water supply line. When the demand stops the system will return to the static state shown here.
Back in the early 1970s when the cross connection program was in its infancy, rules and regulation were still being ironed out. It was the wild wild west of the cross connection era.
This backflow device was installed in 1971. It does not meet modern standards or regulations: 1) It is not testable; 2) A PRV & a Wye strainer have been installed between shut off valve #1 and the check valve assemblies.
Click Photo to Enlarge