Improper Startup of a Backflow Assembly

Manufactures provide pressurization startup procedures for newly installed or repaired backflow prevention assemblies. Failure to read the instructions provided by the manufacturer can result in problems like the one you see here.

As you can see in the 1st photo check valve number 1 is jammed open. This is caused when a contractor does not follow procedure. They opened shut off valve number 2 first and then they opened shut off valve number 1 way too fast.

Typical startup procedures are as follows: With both shut off valves in the closed position, 1^st slowly open shut off valve #1, use the test Cocks to bleed the air out of the assembly, then simply slowly open shut off valve #2.

The picture below shows how the check valve should look in a no flow static condition.