ASSE 6030 cheat sheet

Cross-connection: any actual or potential physical connection between a potable water supply and any source of nonpotable fluid or substance.

Backflow: reverse flow of water or other substances into the distribution system of a public water supply from any source.

Backsiphonage is caused by negative or subatmospheric pressure in the supply piping; backpressure is caused by downstream pressure exceeding supply pressure.

Backflow prevention methods: air gap (physical separation), backflow prevention assemblies (testable), and backflow prevention devices (non-testable, e.g., atmospheric vacuum breaker).

Containment isolation protects the public water main at the service connection; cross-connection isolation protects individual fixtures or zones within a premises.

A pollution hazard degrades water quality (taste, odor, color) without posing a health risk; a contamination hazard creates a health hazard.

Typical backsiphonage hazards: hose bibs with submerged hoses, chemical sprayers, flushometer valves, boiler feed lines, and lawn irrigation systems.

Typical backpressure hazards: boilers, chillers, pumps, elevated storage, and any connection to a system operating at higher pressure than the supply.

Pressure in psi equals head in feet multiplied by 0.433 (for water at 62.4 lb/ft³).

Absolute pressure equals gauge pressure plus atmospheric pressure (about 14.7 psi at sea level).

A perfect vacuum is 0 psia; the maximum theoretical backsiphonage lift at sea level is about 33.9 ft of water (14.7 psi ÷ 0.433).

Flow through an orifice or opening follows Q = C·A·√(2gh), so flow increases with the square root of the pressure differential.

Head loss across a backflow assembly increases with flow rate; manufacturer flow curves define normal and maximum pressure loss.

Water hammer is a pressure surge caused by rapid velocity change; arrestors and slow-closing valves reduce the surge.

Static pressure is the pressure with no flow; residual pressure is the pressure remaining while water is flowing.

A pressure differential across a check valve must exceed the valve's cracking pressure before it opens; a reduced-pressure assembly maintains a differential between zones.

Air gap: physical separation between the potable outlet and the flood-level rim; the only non-mechanical method and provides the highest protection.

Reduced-pressure principle backflow prevention assembly (RP): two independently acting check valves plus a hydraulically operating differential relief valve located between them.

Double check valve assembly (DC): two independently acting check valves with test cocks; used for non-health hazards only.

Pressure vacuum breaker (PVB): loaded check valve and loaded air inlet valve; must be installed above the highest downstream piping and cannot be subject to backpressure.

Atmospheric vacuum breaker (AVB): unloaded air inlet valve; cannot be under continuous pressure and has no test cocks.

Spill-resistant vacuum breaker (SVB): a PVB variant with a check valve that prevents spillage during normal operation and permits installation in pits with drainage.

Hose connection vacuum breaker (HCVB) and dual check valve with intermediate vent are devices, not testable assemblies.

Air gap fittings and barometric loops must terminate at least the specified distance above the flood-level rim and drain to a safe receptor.

ASSE 1001 covers atmospheric vacuum breakers; ASSE 1011 covers hose connection vacuum breakers; ASSE 1012 covers backflow preventer with intermediate vent.

ASSE 1013 covers reduced-pressure principle backflow prevention assemblies; ASSE 1015 covers double check valve assemblies; ASSE 1020 covers pressure vacuum breakers.

ASSE 1024 covers dual check valve backflow preventers; ASSE 1047 covers reduced-pressure detector assemblies; ASSE 1048 covers double check detector assemblies.

ASSE 1056 covers spill-resistant vacuum breakers; ASSE 1052 covers hose connection backflow preventers.

AWWA C511 covers reduced-pressure principle backflow prevention assemblies; AWWA C510 covers double check valve assemblies.

The Safe Drinking Water Act and 40 CFR Part 141 require public water systems to protect the distribution system from contamination.

Model plumbing codes (IPC, UPC) and local cross-connection control ordinances govern installation, testing, and annual certification.

A certified tester must hold the credential required by the local authority having jurisdiction and comply with its testing and reporting rules.

Degree of hazard: health hazard (contamination) requires an air gap or an RP assembly; non-health hazard (pollution) may use a DC, PVB, or other approved device.

Air gap is required where toxic or health-hazard substances could backflow and no other method provides equivalent protection.

RP assemblies are used for high-hazard containment and for premises isolation where backpressure or backsiphonage could introduce health hazards.

DC assemblies are limited to low-hazard (non-health) applications where backpressure is possible but no health hazard exists.

PVB is used for low-hazard backsiphonage only; SVB is used where spillage would be objectionable and drainage is available.

AVB is limited to low-hazard, non-continuous-pressure applications such as individual hose bibs and lawn sprinklers.

Detector assemblies (RPDA, DCDA) are used on fire sprinkler systems to detect unauthorized water use while protecting the supply.

Hazard assessment considers toxicity, connection type, system pressure, and the possibility of backpressure versus backsiphonage.

Air gap: the potable outlet must be at least twice the effective opening diameter above the flood-level rim, and never less than 1 inch.

RP assembly must be installed horizontally, with adequate clearance for testing and repair, and must not be installed in a pit without drainage and access.

DC assembly must be installed horizontally unless the manufacturer lists vertical installation; test cocks must remain accessible.

PVB must be installed at least 12 inches above the highest downstream piping or fixture; check local code for exact height.

AVB must be installed at least 6 inches above the highest point of downstream piping and must not be under continuous pressure.

SVB must be installed at least 12 inches above the highest downstream piping and must have a drain for spillage.

Assemblies must be protected from freezing, backpressure, and unauthorized removal; installers must follow manufacturer's instructions and local code.

Test cocks and shutoff valves must be accessible for testing; strainers and bypasses must not defeat assembly protection.

Test sequence for an RP assembly: record supply pressure, check check valve #1 tightness, check relief valve opening point, check check valve #2 tightness, and record final readings.

Relief valve opening point must be at least 2 psi below the supply pressure and the assembly must maintain the required differential.

Check valve tightness is verified by observing pressure hold on the gauge with the upstream or downstream shutoff closed.

A DC assembly passes if both check valves hold pressure and no continuous leakage occurs through test cocks.

A PVB passes if the air inlet opens at the specified vacuum and the check valve holds; a failed air inlet indicates a defective check or fouled seat.

Common failures: debris on seats, worn O-rings, damaged relief valve diaphragms, and improperly adjusted springs.

Record test results on the form required by the local authority; include tester certification number, date, and gauge calibration information.

Test gauges must be calibrated and within the accuracy tolerance specified by the jurisdiction; record calibration dates.

A cross-connection control program includes hazard surveys, device inventories, installation permits, annual testing, and enforcement.

Records should include device location, make, model, size, serial number, installation date, test results, and tester identification.

Annual testing is typical; the authority having jurisdiction may require more frequent testing for high-hazard installations.

Program administration includes tester certification, continuing education, and public education on cross-connection hazards.

Safety: use personal protective equipment, lockout/tagout, and confined-space procedures when working in pits or vaults.

Before testing, confirm the assembly is isolated and depressurized; release pressure slowly to avoid water hammer and injury.

Documentation must be retained per local retention schedules and made available to the authority upon request.

Noncompliance procedures include notification, re-test deadlines, and possible termination of water service.