9.3 Comparing the Four Practical-Exam Assemblies
Key Takeaways
- Practical exam assemblies are RP 1013, DC 1015, PVB 1020, and SVB 1056—memorize device numbers with components and pass criteria.
- RP unique numbers: relief ≥ 2.0 psid and check #1 ≥ 5.0 psid and above relief; check #2 is tight or leaked with no psid recorded.
- DC: two checks ≥ 1.0 psid each, no relief valve—never invent a dump test.
- PVB/SVB: check ≥ 1.0 psid and air inlet ≥ 1.0 psid above atmospheric; SVB adds spill resistance, not new pass floors.
- Twenty-second visual ID (plate, relief vs air inlet, check count) prevents running the wrong script under the 90-minute clock.
9.3 Comparing the Four Practical-Exam Assemblies
Quick Answer: The ASSE 5110 practical requires correct field tests on four assemblies: RP (1013), DC (1015), PVB (1020), and SVB (1056). Memorize each device’s components, hazard/hydraulic role, tests performed, and key pass numbers so you never run an RP relief script on a DC or invent a second check on a PVB.
Master comparison table
| Feature | RP ASSE 1013 | DC ASSE 1015 | PVB ASSE 1020 | SVB ASSE 1056 |
|---|---|---|---|---|
| Core internals | 2 independent checks + differential pressure relief in the zone | 2 independent checks, no relief | Loaded check + independent air inlet | Loaded check + spill-resistant air inlet path |
| Shutoffs | 2 resilient-seated | 2 resilient-seated | 2 resilient-seated | 2 resilient-seated |
| Test cocks | Typically 4 (TC1–TC4) | Typically 4 | Commonly 2 | Typically 1 (plus the vent valve) |
| Protects against | Backpressure and backsiphonage | Backpressure and backsiphonage (lower hazard class) | Backsiphonage only | Backsiphonage only |
| Continuous pressure | Yes | Yes | Yes | Yes |
| Typical hazard class | Health (contamination) as approved | Non-health (pollution) as approved | Per AHJ; siphonage applications (often irrigation/process) | Same vacuum-breaker family; preferred where spillage is a problem |
| Key tests | Relief opening; check #1; check #2 | Check #1; check #2 | Check; air inlet | Check; air inlet |
| Headline pass numbers (USC typical) | Relief ≥ 2.0 psid; check #1 ≥ 5.0 psid and above relief; check #2 tight (no psid) | Each check ≥ 1.0 psid | Check ≥ 1.0 psid; air inlet ≥ 1.0 psid above atmospheric | Same as PVB family |
| Atmospheric dump signal | Relief can discharge | None in normal design | Air inlet opens to atmosphere | Air inlet opens; spillage minimized |
| Elevation / special install | Drainage & air gap for relief discharge critical | Orientation/clearance | Air-inlet critical level ≥ ~12 in above highest outlet | Same elevation class as PVB |
Memory hooks for practical day
Use short hooks you can recite while walking to the stand:
- “Thirteen is reduced pressure.” 1013 = RP → relief story (2.0 / 5.0 / 1.0).
- “Fifteen is double check.” 1015 = DC → two checks, no relief, both ≥ 1.0.
- “Twenty is pressure vacuum.” 1020 = PVB → check + air inlet, both ≥ 1.0; elevation 12 in.
- “Fifty-six doesn’t spit.” 1056 = SVB → same 1.0 / 1.0 family as PVB, spill-resistant manners.
- “One dump or no dump.” RP dumps via relief; DC has no dump; PVB/SVB dump air path via air inlet, not a zone relief.
Number flash card (write this once, say it often)
| Device # | Name | Numbers you must not forget |
|---|---|---|
| 1013 | RP | Relief ≥ 2.0; CK1 ≥ 5.0 & > relief; CK2 tight (no psid) |
| 1015 | DC | CK1 ≥ 1.0; CK2 ≥ 1.0 |
| 1020 | PVB | Check ≥ 1.0; air inlet ≥ 1.0 psid above atmospheric |
| 1056 | SVB | Check ≥ 1.0; air inlet ≥ 1.0 psid above atmospheric |
What you never do (practical landmines)
| Never do | Why it fails the outcome |
|---|---|
| Treat a DC like it has a relief | You will invent a dump test that does not exist and miss real check work |
| Treat a PVB/SVB like an RP | You will hunt for a zone relief and skip air-inlet opening |
| Apply 5.0 psid as the universal check minimum | 5.0 is RP check #1 under USC 10th—not DC checks, not PVB/SVB checks |
| Use a PVB under backpressure application logic on the written | Vacuum breakers do not replace RPs on backpressure health hazards |
| Skip visual ID | Wrong assembly → wrong entire procedure under the clock |
| Leave air in the gauge | False differentials on every type |
| “Pass” a PVB that opens at 0.8 because “close enough” | Minimums are floors, not suggestions |
| Ignore elevation on vacuum breakers | Geometry can nullify a pretty gauge reading |
Component checklist you can run in 20 seconds
At each stand, force this micro-scan before hoses:
- Name plate / standard number → 1013 / 1015 / 1020 / 1056.
- How many checks? Two (RP/DC) vs one loaded check + air inlet (PVB/SVB).
- Is there a relief canopy/port between checks? Yes → think RP. No mid-body relief → not RP.
- Is there a top air inlet / vented canopy? Think PVB/SVB; then decide spill-resistant vs conventional by plate and behavior.
- Shutoffs both present? If not, it may not be a complete testable assembly.
How the tests differ in “feel”
| Assembly | Dominant sensory/procedure cue | Time sink if you are rusty |
|---|---|---|
| RP | Watching relief spit at the opening point; managing zone differentials | Relief + three readings; order discipline |
| DC | Quiet—no atmospheric dump; pure check tightness | Convincing yourself both checks really hold without a relief “signal” |
| PVB | Air inlet motion + possible spit; elevation glance | Clean air-inlet opening mark on the gauge |
| SVB | Quieter start-up; subtler vent cues | Same as PVB but without puddle feedback |
Integrating hazard language (written + practical talk)
When a proctor or written stem asks why an assembly is present:
- RP: health hazard, continuous pressure, possible backpressure and/or siphonage.
- DC: non-health as allowed, continuous pressure, backpressure/siphonage—not for toxic contamination loads.
- PVB/SVB: backsiphonage protection under continuous pressure; not for backpressure; elevation critical; SVB when spillage must be controlled.
You are a tester, not the final AHJ, but you must recognize mismatches (for example, a DC on a clearly toxic feed) and report observations. Do not “upgrade” an assembly by imagination during the practical—test what is on the stand with the correct procedure for that device standard.
Mini case: four stands in sequence
Stand A shows a mid-body relief port and four test cocks → RP script (2.0 / 5.0 / 1.0).
Stand B shows two checks, no relief → DC script (1.0 / 1.0).
Stand C shows a top air inlet and irrigation-style elevation → PVB script (1.0 / 1.0).
Stand D looks similar to C but plate says 1056 and stays dry on fill → SVB script (still 1.0 / 1.0).
If you start measuring a “relief opening” on Stand B, you have already adversely affected the demonstration—even if your hands are steady.
Bridge
With the four-assembly map fixed, Section 9.4 turns the comparison into exam-day choreography: 90 continuous minutes, fail-mode completeness, second-attempt rules, report discipline, and how not to self-destruct under proctor eyes.
Which set correctly matches device standards to the four ASSE 5110 practical assemblies?
Which headline pass numbers belong to an RP (ASSE 1013) under USC 10th Edition-style criteria—not to a PVB?
Why must you never treat a DC like it has a relief valve during the practical?
Which statement correctly contrasts PVB/SVB protection with RP protection?