ASSE 6010 cheat sheet

Backflow is reverse flow into potable water; its two causes are backsiphonage from negative supply pressure and backpressure from downstream pressure exceeding supply pressure.

A cross-connection is any actual or potential connection between potable water and a nonpotable source.

Air gap minimum separation is at least 1 inch or twice the effective opening diameter, whichever is greater, above the flood-level rim.

Health hazard involves contamination that can cause illness or death; non-health hazard involves pollution that is objectionable but not immediately harmful.

1 psi equals 2.31 feet of water column; 1 foot of water column equals 0.433 psi; atmospheric pressure at sea level is 14.7 psi.

Backsiphonage can occur during main breaks, firefighting demand, pump failure, or at elevated points in the system.

Thermal expansion in a closed system can create backpressure and cause backflow.

AVB and PVB devices are limited to non-health hazards; RPZ assemblies and air gaps are used for health hazards.

The Safe Drinking Water Act establishes federal oversight; states and local health departments enforce cross-connection control programs.

Containment protection is installed at the water service entrance to protect the public main; isolation protection protects piping inside a building.

Core program elements include cross-connection surveys, hazard classification, device approval, installation permits, testing, records, and enforcement.

Testable backflow prevention assemblies commonly require annual field testing, with the exact frequency set by the authority having jurisdiction or water purveyor.

Approved assemblies must be listed by a recognized body such as ASSE, UL, or the USC Foundation for Cross-Connection Control and accepted by the local authority.

ASSE 6010 is a professional qualification standard for backflow prevention assembly testers.

Test reports are typically submitted to the water purveyor, property owner, and authority having jurisdiction; retention periods vary by jurisdiction.

New construction and renovations generally require plan review and cross-connection control approval before water service is activated.

Device selection follows the degree of hazard and whether containment or isolation protection is required.

An RPZ assembly has two check valves and a differential relief valve; it is used for health hazards and discharges to a drain through an air gap.

A DCVA has two check valves and no relief valve; it is testable and used for non-health hazards.

A PVB has a check valve and an air inlet; it must be installed at least 6 inches above the highest downstream outlet and cannot be under continuous pressure for more than 12 hours.

An AVB has an air inlet and check valve; it cannot have a downstream shutoff or be under continuous pressure and is limited to non-health hazards.

An air gap is a physical vertical separation with no mechanical parts and provides the highest degree of backflow protection.

RPZ test cocks are numbered upstream to downstream: #1 upstream of check #1, #2 between checks, #3 downstream of check #2, and #4 at the relief valve.

A dual check valve is non-testable and is limited to low or non-health hazards where the authority allows it.

Installation must follow manufacturer requirements for orientation, clearance, drain location, and freeze protection.

A backflow test kit includes a differential pressure gauge, hoses, fittings, and test cock adapters; the gauge must be calibrated and zeroed.

Flush test cocks before connecting hoses to remove debris and prevent contamination or gauge damage.

Record supply pressure, differential pressures, and relief valve opening point on the test report.

RPZ field testing commonly includes check #1 tightness, check #2 tightness, relief valve opening point, and differential pressure across check #1.

DCVA testing verifies that both check valves hold against reverse pressure without leaking.

PVB testing verifies check valve tightness and air inlet opening.

Test cocks are numbered from upstream to downstream, with #1 on the supply side.

The gauge high side connects upstream and the low side connects downstream; differential pressure equals high-side pressure minus low-side pressure.

An assembly fails if a check leaks, the relief valve opens outside manufacturer or authority limits, or required differential pressure is not maintained.

Continuous relief valve discharge from an RPZ often indicates a leaking check #1, leaking check #2, debris on the relief seat, thermal expansion, or low supply pressure.

A PVB that spits or leaks from the air inlet often has a fouled check valve, damaged seat, debris, or downstream pressure.

DCVA test failure commonly calls for cleaning or replacing check discs, springs, and seats and removing debris or scale.

Use manufacturer-approved repair parts and reassemble the assembly to manufacturer specifications.

Clean strainers and flush assemblies during routine maintenance to remove debris that can cause check valve failure.

Freeze protection requires draining the assembly, insulating it, and protecting the relief valve discharge from freezing.

Never remove check valves, bypass an assembly, or alter relief valve settings to make a test pass.

After any repair or component replacement, retest the assembly and record the results before returning it to service.

Leaking test cocks should be replaced rather than overtightened, which can damage the assembly body.