Sunday, May 8, 2016

FDC By-Pass

Some AHJs require a "by-pass", manually operated and normally closed, to be piped around the FDC check valve.  These are invaluable in back flushing otherwise contaminated FDC connections. Arrow points to the top end of the by-pass.  The FDC check valve is shown on the right.

Another by-pass installation:

Close up:

And another FDC-By-Pass, in a desert environment, overseas:

Another FDC by-pass:


  1. I take it none of these bypass valves have deficiencies?

    1. That's not entirely correct. Every control valve should have a sign, even if the valve is normally closed. These by-pass systems are only used for maintenance, to back flush the systems, normally the valves are closed. Also, in some jurisdictions the valves would require a chain lock, a plastic tamper evident seal or an electrical switch indicating the valve's position (open or closed). I would say about 10% of the places I have worked require them. These particular ones were located in Boulder, Colorado. In theory, these by-passes really can't cause a system to fail.