ASSE 6010 key terms

Any actual or potential link between a potable water system and a source of contamination or pollution that could allow nonpotable fluid to enter the drinking water supply.

The unwanted reverse flow of water or other substances into the potable water system, moving opposite to the intended direction of flow. It is caused by either backsiphonage or backpressure.

Reverse flow created when pressure in the supply piping drops below atmospheric, pulling nonpotable liquid through a cross-connection into the system. Main breaks and heavy fire demand are common causes.

Reverse flow created when pressure downstream of a cross-connection is higher than the supply pressure, forcing nonpotable fluid into the potable system. Boilers, pumps, and elevated tanks are typical sources.

The unobstructed vertical distance between the lowest opening of a water outlet and the flood level rim of the vessel it fills. It is the only absolute form of backflow protection.

The edge or rim of a receptacle or fixture over which water would spill. It serves as the reference point for setting a required air gap or a vacuum breaker's critical level.

A marking established by the manufacturer showing the minimum elevation at which a vacuum breaker must be installed relative to the flood level rim of the fixture or piping it protects.

A cross-connection condition in which the contaminant could cause illness or death, such as sewage, toxic chemicals, or radioactive material. It requires the highest degree of protection available.

A cross-connection condition in which the contaminant would only degrade the taste, odor, or appearance of drinking water and is not expected to cause illness, such as a food-grade dye.

A rating that combines the toxicity of the potential contaminant with the likelihood that backflow will occur, and that determines which type of backflow prevention assembly must be installed.

Protection installed on the service line, usually just downstream of the water meter, so the customer's entire plumbing system cannot backflow into the public water main.

Protection installed at an individual fixture, appliance, or process connection to keep a local hazard from contaminating the building's own drinking water distribution system.

The health department, building department, water utility, or other body that adopts the cross-connection control ordinance, approves assemblies, issues permits, and enforces testing and reporting requirements.

A person who has completed an approved training course, passed written and practical examinations, and keeps certification current in order to legally test and report on backflow prevention assemblies.

A program rule found in most cross-connection ordinances requiring each testable assembly to be field tested at least once every twelve months, with the results filed with the authority.

A testable assembly with two spring-loaded check valves and a differential relief valve between them. The relief valve discharges to atmosphere if a check leaks, giving protection against both backsiphonage and backpressure for health hazards.

A testable assembly of two independent spring-loaded check valves with test cocks and shutoff valves. It is approved only for non-health hazards because it provides no relief against backpressure.

A double check valve assembly fitted with a parallel bypass line containing a water meter and a smaller double check, used on fire sprinkler systems so that low and domestic-type flows still register.

A testable assembly with a spring-loaded check valve and an air inlet that opens when supply pressure drops. It protects against backsiphonage only and must be installed above all downstream piping.

A vacuum breaker whose air inlet is held closed by a check valve so it does not spill water during normal flow, permitting continuous pressure service. It protects against backsiphonage only.

A simple non-testable device whose air inlet opens at atmospheric pressure and seals when water flows. It cannot be installed under continuous pressure or downstream of a shutoff valve.

A non-testable device with hose threads that screws onto a sillcock to prevent backsiphonage through a garden hose or portable equipment. It must be removed where freezing occurs.

A length of pipe formed into an inverted U at least 35 feet high, where the standing column of water prevents backsiphonage. It offers no protection against backpressure.

A valve that permits flow in one direction only and closes automatically when flow reverses. In testable backflow assemblies the checks are spring loaded and operate independently of each other.

The hydraulically operated valve located between the checks of a reduced pressure assembly. It opens to atmosphere when the pressure differential across the first check falls below its set value, preventing backpressure and backsiphonage.

The full-port valves immediately upstream and downstream of an assembly that allow a tester to isolate and depressurize it for testing or repair without shutting down the entire building.

A condition in which a device is subjected to water pressure for more than twelve continuous hours. Devices rated for this service must include a check valve to prevent spilling or discharge.

A small quarter-turn valve with a screwdriver slot located on a backflow assembly, used to attach test hoses, bleed air, and read pressure at a specific point during field testing.

The difference between the pressure at the assembly inlet and the pressure between the checks, or across a single check. Assemblies must hold a minimum differential to pass a field test.

Checking a field test gauge against a certified reference and documenting the result, usually once a year. A gauge found out of tolerance makes every test performed with it invalid.

Briefly opening and closing test cocks to push air and debris out of the gauge hoses so pressure readings settle quickly and reflect true conditions in the assembly.

Watching a gauge for a specified period with flow shut off to confirm that a check valve or relief valve keeps its required pressure difference or opening point without drifting.

The form recording assembly location, make, model, size, serial number, gauge readings, and pass or fail result, filed with the authority with a copy left on site for the owner.

Pressure buildup in a closed piping system when heated water has nowhere to expand, which can damage an assembly or cause repeated discharge from a relief valve.

A sharp pressure surge caused by a sudden stop or change in flow velocity, capable of cracking seats, loosening check valves, and producing false gauge readings during a test.

Sand, scale, or pipe chips caught on a seat, disc, or relief valve so it cannot seal tightly. It is a leading reason an assembly fails its test and must be disassembled and cleaned.

The elastomeric parts of an assembly, including seat discs, O-rings, diaphragms, and gaskets, which harden, swell, or tear with age and are replaced during routine repair.

Cracks or splits in the body, bonnet, or relief valve caused by water expanding as it freezes. It is avoided by installing assemblies in protected, drainable locations.