Backflow Preventer Sizing
Select and size backflow assemblies per code
Flow Requirements
Backflow Prevention Results
Required Assembly
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Minimum Size
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Estimated Pressure Loss
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Testing Required
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Installation
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Assembly Types
| Type | Protection | Test Req'd |
|---|---|---|
| AVB | Backsiphonage only | No |
| PVB | Backsiphonage only | Annual |
| SVB | Backsiphonage only | No |
| DCVA | Low hazard, both | Annual |
| RPBA | High hazard, both | Annual |
| AG | High hazard | No |
Backflow Assembly Guide
Air Gap (AG)
Highest protection level. Physical separation between outlet and flood rim. Required for sewage and toxic chemicals.
No testing required
RP/RPBA
Reduced Pressure Backflow Assembly. Provides high-hazard protection against both backpressure and backsiphonage.
Annual testing required
DC/DCVA
Double Check Valve Assembly. For low-hazard applications with backpressure or backsiphonage risk.
Annual testing required