A spill-resistant vacuum breaker does the same job as a pressure vacuum breaker and solves the one thing people dislike about them.
A standard PVB discharges a little water through the air inlet each time the system starts up and the inlet closes. Outside on a lawn nobody notices. Inside a building, on a finished floor, or over anything that should stay dry, it is a real problem.
The spill-resistant version adds a diaphragm and a different startup sequence so the air inlet seals before water reaches it. The protection is identical; the puddle is not there.
What it does and does not do
The same as a PVB, which is worth being clear about. It protects against backsiphonage only. It does nothing about backpressure, so anything with a pump or elevated head behind it belongs on a reduced pressure assembly.
It can sit under continuous pressure, valves can go downstream of it, and it has to be mounted above the highest outlet it protects — typically twelve inches, as with a PVB.
Where you find one
Indoors, mostly, and anywhere a discharge would cause trouble: mechanical rooms, laboratory and equipment connections that are suction-only, and indoor pool and spa fill lines. It shows up less often than a PVB on the Western Slope, and almost always for the spill reason rather than any difference in protection.
Testing
It is a testable assembly, certified once a year by a certified technician with the report filed directly to your provider.
Where one sits inside the building, we test and repair it but do not replace it — that line is explained here.
Schedule a backflow test or call 970-835-9661