Hydraulic Principles
30%of exam
Assemblies Equipment
30%of exam
Field Test Procedures
20%of exam
Cross-Connection Control
10%of exam
ContainmentIsolationSurveysAir GapHazard Rating
Field Test Equipment
5%of exam
Differential GaugeHosesTest CocksBleedingCalibration
Codes Regulations
5%of exam
SDWAPurveyorRecordsReportingRecertification
Quick Facts
- Exam
- Backflow Tester
- Bodies
- ABPA / ASSE
- Written
- 100 questions
- Time
- 3 hours
- Pass
- 70%
- Practical
- Hands-on testing
- Assemblies
- RP DC PVB SVB
- Validity
- 3 years
- Gauge
- Annual calibration
Two Backflows
Pressure pushes; siphon pulls.
BackpressureBacksiphonage
Backpressure vs Backsiphonage
Backpressure
- Downstream pressure higher
- Pumps/boilers cause
Backsiphonage
- Supply pressure drops
- Vacuum draws back
Pressure direction decides
Selection Picker
- Health hazard→RP or air gap
- Low hazard→DC
- Backpressure exists→RP/DC(Not PVB)
- Backsiphonage only→PVB/SVB
- Maximum protection→Air gap
- Fixture protection→Isolation
Hydraulics Basics
- Backflow
- Reverse flow
- Backpressure
- Downstream pressure higher
- Backsiphonage
- Supply pressure drops
- Static pressure
- No-flow pressure
- Dynamic pressure
- Flowing pressure
- Pressure loss
- Drop across device
RP Parts
Check, zone, relief, check.
Check 1ZoneReliefCheck 2
RP vs DC
RP
- Relief valve present
- High hazard use
DC
- No relief valve
- Low hazard use
Health hazard needs RP
Failure Picker
- Reading unstable→Bleed hoses
- Check leaks→Clean seat
- Relief won't open→Inspect diaphragm
- Shutoff leaks→Repair shutoff
- Gauge suspect→Check calibration
- Wrong assembly→Hazard review
RP Assembly
- RP
- Reduced pressure principle
- Check 1
- Creates zone pressure
- Check 2
- Prevents outlet return
- Relief valve
- Vents failed zone
- Zone
- Reduced pressure area
- Use
- High hazard protection
PVB vs SVB
PVB
- Vacuum breaker
- May spill water
SVB
- Spill-resistant design
- Vacuum breaker
Both backsiphonage only
DC Assembly
- DC
- Double check assembly
- Check 1
- First closure point
- Check 2
- Second closure point
- Shutoff 1
- Inlet isolation
- Shutoff 2
- Outlet isolation
- Use
- Low hazard protection
Device vs Assembly
Device
- Often non-testable
- No test cocks
Assembly
- Field testable
- Has shutoffs/cocks
Testability matters
PVB SVB
- PVB
- Pressure vacuum breaker
- SVB
- Spill-resistant breaker
- Air inlet
- Opens on vacuum
- Check valve
- Holds downstream water
- Backpressure
- Not protected
- Elevation
- Install above outlets
Troubleshooting
- Debris
- Fouls check seat
- Scale
- Restricts movement
- Spring
- Weak closure force
- Diaphragm
- Relief valve failure
- Leaky shutoff
- Invalid test
- Air in hose
- Unstable reading
Test Start
Identify, isolate, connect, bleed.
IdentifyIsolateConnectBleed
Test Picker
- Before connection→Gauge zero
- Hoses attached→Bleed air
- RP assembly→Relief plus checks
- DC assembly→Two checks
- PVB/SVB→Air inlet/check
- Any failure→Repair retest
Test Setup
- Permission
- Notify responsible party
- Flow direction
- Confirm before testing
- Test cocks
- Open slowly
- Bleed hoses
- Remove trapped air
- Gauge zero
- Check before readings
- Record
- Document findings
RP Test Logic
- Relief opening
- Must open
- Zone pressure
- Lower than supply
- Check 1
- Holds differential
- Check 2
- Holds backpressure
- Shutoff 2
- Must be tight
- Fail
- Repair then retest
DC PVB Tests
- DC check 1
- Must hold tight
- DC check 2
- Must hold tight
- DC shutoff
- No leakage
- PVB check
- Holds pressure
- Air inlet
- Opens to atmosphere
- SVB spill
- Minimized discharge
Containment vs Isolation
Containment
- Service entrance
- Protects public system
Isolation
- Individual fixture
- Protects internal users
Location decides
Hazard Control
- Cross-connection
- Potable/nonpotable link
- Pollution
- Aesthetic quality hazard
- Contamination
- Health hazard
- Containment
- Service protection
- Isolation
- Fixture protection
- Air gap
- Physical separation
Pollution vs Contamination
Pollution
- Aesthetic concern
- Non-health hazard
Contamination
- Health concern
- Toxic/pathogenic hazard
Health risk escalates
Test Kit
- Differential gauge
- Measures pressure difference
- High hose
- Connect upstream side
- Low hose
- Connect downstream side
- Bypass hose
- Equalizes as needed
- Calibration
- Check yearly
- Needle valves
- Control gauge flow
Report Basics
Assembly, readings, result, signature.
AssemblyReadingsResultSignature
Records Regs
- SDWA
- Drinking water law
- Purveyor
- Water supplier
- Authority
- Local program rules
- Report
- Submit test results
- Serial number
- Assembly identifier
- Recertify
- Renew credential
Common Traps
PVB Trap
Backsiphonage only ≠ Backpressure protection
Hazard Trap
Pollution ≠ Contamination
Gauge Trap
Air in hose ≠ True pressure
Shutoff Trap
Leaky shutoff ≠ Valid test
RP Trap
Relief valve opens ≠ Relief valve closed
Location Trap
Containment ≠ Isolation
Last Minute
- 1.Name two backflow types
- 2.Classify hazard first
- 3.Match assembly to hazard
- 4.Confirm flow direction
- 5.Bleed gauge hoses
- 6.Test shutoffs matter
- 7.RP relief must open
- 8.PVB excludes backpressure
- 9.Record serial number
- 10.Repair then retest
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