ASSE 5120 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cross-connection

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

Backflow

The unintended reverse flow of water or another substance into a potable water distribution system, caused by either backsiphonage or backpressure conditions within the piping.

Backsiphonage

Backflow produced by a negative or sub-atmospheric pressure in the supply piping, which draws downstream liquid into the potable system through an unprotected cross-connection.

Backpressure

Backflow caused when pressure downstream of a connection exceeds the supply pressure, forcing water backward; common sources are boilers, pumps, and elevated storage.

Pollutant versus contaminant

A pollutant impairs taste, odor, or appearance without creating a health hazard; a contaminant causes an actual health hazard, so it demands higher-level protection.

Air gap protection

A physical separation between the supply outlet and the flood-level rim of the receiving vessel, giving absolute protection without mechanical parts that can fail.

Pounds per square inch to head

One psi equals 2.31 feet of water column, and one foot of water column equals 0.433 psi; these conversions let you translate gauge readings into elevation head.

Atmospheric pressure at sea level

Standard atmospheric pressure is about 14.7 psi, or 101.3 kilopascals, which limits the maximum theoretical vacuum a backsiphonage condition can create.

Orifice flow relationship

Flow through a fixed opening varies with the square root of the pressure differential, so quadrupling the differential doubles the discharge rate through that orifice.

Friction loss and velocity

Friction head loss in a given pipe rises approximately with the square of velocity, so doubling the flow rate produces roughly four times the loss per unit length.

Water hammer

A pressure surge created by rapid changes in flow velocity, such as fast valve closure, which can damage piping and backflow assembly internals.

Thermal expansion backflow

Heating water in a closed system isolated by a check valve raises pressure, which can force water backward or require a thermal expansion control device.

Cavitation damage

Vapor bubbles forming where local pressure drops below vapor pressure collapse violently, eroding check components and causing chatter or premature assembly failure.

Atmospheric vacuum breaker

A device with an air inlet that opens at atmospheric pressure, installed at least six inches above downstream outlets and unsuitable for continuous pressure or backpressure.

Pressure vacuum breaker

A spring-loaded check combined with an air inlet, installed at least twelve inches above the highest downstream outlet, protecting only against backsiphonage.

Double check valve assembly

Two independently acting check valves with test cocks, used for low-hazard protection against both backsiphonage and backpressure, with no relief vent to atmosphere.

Reduced pressure principle assembly

A high-hazard assembly with two spring-loaded checks and a differential relief valve that discharges when supply pressure drops or the first check fails.

Spill-resistant vacuum breaker

A pressure vacuum breaker variant with a loaded air inlet check that seals during normal operation to prevent spilling, still limited to backsiphonage protection.

Detector assembly purpose

Fire-line assemblies with a metered bypass and small check valve that detect unauthorized water use while still protecting the potable main from backflow.

Hose-bibb vacuum breaker

A small threaded device for hose connections that admits air on backsiphonage; it cannot be used under continuous pressure or where backpressure exists.

Differential pressure test kit

The field instrument with a needle valve, sight tube, and calibrated gauge used to measure check holding pressures and relief valve opening points.

RP relief valve criterion

The relief valve should open when the differential between the two check zones falls to about two psi or less, confirming hydraulic dependence.

Check valve holding test

A test confirming each check resists reverse flow and records the differential pressure at which it holds, commonly at least one psi.

PVB air inlet test

A test verifying the air inlet opens at one psi or more of negative pressure and that the check holds at least one psi against reverse flow.

Pre-test isolation steps

Confirm no downstream flow, close isolation valves, and flush test cocks before measuring, then restore the assembly and check for leaks afterward.

Gauge calibration record

Documented certification of test gauge accuracy against a known reference, since gauge error becomes test-result error and can invalidate reported readings.

ASSE device standards

Numbered standards identify devices, such as 1001 for atmospheric vacuum breakers, 1013 for double check assemblies, and 1015 for reduced pressure assemblies.

Containment versus isolation

Containment protects the public main at the service connection; isolation protects fixtures and processes inside the building at each point of use.

Testing frequency

Annual testing is typical, but local ordinance governs; installation, repair, relocation, and change of use often trigger additional required tests.

Program administrative elements

An effective cross-connection program includes an ordinance, hazard surveys, device inventory, certified testers, records retention, and enforcement procedures.

Required test report records

Reports should capture device make, model, serial number, size, location, gauge readings, tester identity and certification, date, and pass or fail result.

Failed device handling

A failed assembly is tagged, reported to the purveyor, and either repaired and retested or replaced; the purveyor may order service interruption.