ASSE 6020 common mistakes
ASSE 6020 · Understand the traps and how to avoid them.
When asked to identify a reduced pressure principle assembly's zone, candidates describe the zone as the space between the first and second check valves rather than the space between the first check and the relief valve seat, and they misstate which condition (supply pressure drop versus backpressure) opens the relief valve.
The RP assembly has two checks and a differential relief valve, and candidates conflate the intermediate zone with the check-to-check cavity of a double check assembly. Diagrams in study habits often blur the relief valve's sensing line, so the candidate cannot trace which side of the diaphragm sees supply pressure.
What to do instead
Redraw the RP from memory labeling each component and both sensing lines: the relief valve opens when the zone pressure rises relative to supply (supply drop or backpressure on check one) and closes when supply is restored. Practice stating the rule aloud: relief discharges to protect the zone, and the zone must sit below the supply pressure by the designed differential.
Candidates report gauge readings during a field test without applying the correct correction for gauge elevation relative to the assembly, and they record readings at the wrong reference point for the test being performed.
Test forms and procedures reference readings at specific taps, and candidates memorize numbers without understanding that a gauge located above or below the assembly reads a different static head. They also confuse the low-hose-side reading with the assembly inlet reading.
What to do instead
Work through head conversion (0.433 psi per foot of water) with concrete examples, and rehearse which tap each reading corresponds to for each assembly type. On every practice test, write the tap location next to the number before evaluating it against the pass criteria.
Candidates treat the required minimum pressure differential for an RP relief valve as a single fixed number and apply it regardless of the assembly's rated flow, or they confuse the relief valve opening point with the check valve opening point.
The relief valve must open at a specified differential below supply, and the check valves have separate opening requirements. Candidates memorize one threshold and reuse it for all three components, and they do not distinguish the static differential from the flowing condition.
What to do instead
Build a comparison table listing each component (first check, second check, relief valve) with its own criterion and the condition under which it is measured. Verify current values against the applicable standard rather than memory, and state the component name before stating the number in every practice answer.
When troubleshooting a failed test, candidates replace the assembly or its check valves before confirming that the failure is real, ignoring dirty test cocks, hoses, gauge calibration, and debris fouling the seat.
Field-test failures often originate in the test setup, not the assembly. Candidates under time pressure jump to the repair step because repair feels like the 'real' answer, and they have not internalized a diagnostic sequence.
What to do instead
Adopt and recite a fixed sequence: verify gauge calibration and zero, inspect and flush test cocks and hoses, retest, then open the assembly and inspect seats and discs. In practice questions, eliminate any answer that begins with replacement before verification.
Candidates misclassify the degree of hazard and therefore choose the wrong minimum assembly type, for example permitting a double check assembly where a reduced pressure principle assembly is required for a high-hazard connection.
The distinction turns on whether the hazard is health-related (toxic or biological) versus non-health, and candidates focus on the plumbing arrangement instead of the contaminant. They also forget that some applications are governed by local rules that are stricter than the general standard.
What to do instead
Practice classifying contaminants explicitly as health hazard or non-health hazard first, then map the classification to the minimum assembly. Memorize the principle that high hazard requires protection against both backpressure and backsiphonage with a relief valve, and always check the local authority's list before finalizing.
Candidates confuse backsiphonage with backpressure and select the wrong scenario when asked which condition a device protects against, especially for air gaps, vacuum breakers, and barometric loops.
Both are backflow, and the difference is the direction of the pressure relationship rather than the direction of flow. Candidates memorize device names without linking each device to the pressure condition it addresses.
What to do instead
For each device, write one sentence naming the mechanism it resists: atmospheric vacuum breaker and air gap address backsiphonage, while a barometric loop addresses backsiphonage only and cannot protect against backpressure. Test yourself by covering the device name and reading only the mechanism sentence.
Candidates describe program administration tasks vaguely, such as 'keep records' or 'enforce the rules', without naming the specific elements of a cross-connection control program: inventory, hazard assessment, device selection, installation approval, testing frequency, notification, and enforcement.
Administration content feels like common sense, so candidates skim it and answer with generalities. Exam items often ask which element is missing or which step comes next, which requires an ordered list rather than a general impression.
What to do instead
Memorize the program as an ordered lifecycle from survey and inventory through hazard classification, requirement issuance, installation inspection, periodic testing, record retention, and enforcement for noncompliance. Practice sequencing questions by writing the lifecycle from memory and checking it against the ordinance language.
Candidates state that an assembly must be tested annually without qualification, ignoring that testing frequency is set by the local jurisdiction and that certain conditions (relocation, repair, seasonal shutdown, or a change in use) trigger retesting.
Annual testing is the common default, so candidates treat it as universal law. They overlook that the authority having jurisdiction sets the interval and that repair or relocation requires a new test regardless of the calendar.
What to do instead
Frame every frequency answer as 'the interval established by the local program, commonly annual' and separately list the events that require an immediate retest. When a question mentions repair or relocation, check for a retest requirement before answering.
Candidates perform or describe a test on a pressure vacuum breaker or spill-resistant vacuum breaker using procedures appropriate to a double check assembly, and they fail to account for the device's critical level and the effect of the shutoff valve position.
Vacuum breaker testing differs because the device relies on a float and an air inlet, and the critical level must be verified relative to the device. Candidates who learned one test sequence apply it uniformly across assembly types.
What to do instead
Maintain a separate procedure card for each device family and rehearse the distinguishing steps: for vacuum breakers, confirm the air inlet opens and the critical level is not exceeded, and note how closing the downstream shutoff changes the reading. Never transfer a check-valve test sequence to a vacuum breaker.
Candidates answer hydraulic questions about friction loss and pressure change using intuition, asserting that flow increase raises downstream pressure or that smaller pipe reduces velocity, rather than applying the relationships among flow, velocity, pipe diameter, and friction loss.
Hydraulic relationships are counterintuitive when memorized as words rather than formulas. Candidates recall fragments of the velocity and friction loss relationships and reverse them under exam pressure.
What to do instead
Anchor each answer to the governing relationship: velocity rises with flow and falls with the square of diameter, and friction loss rises steeply with flow and with velocity. Work numeric practice problems until the direction of each effect is automatic, then sanity-check every conceptual answer against those relationships.