Installation Requirements & Field Conditions
Orientation, flow direction, drainage, freeze protection, accessibility, and relocation requirements.
- Identify proper installation orientation and flow direction for all assembly types
- Explain freeze protection requirements and methods
- Describe clearance and accessibility requirements for testing and maintenance
- Identify bypass hazards and explain why bypasses must be protected
- List required PPE for backflow testing and installation work
Leçon 1
Installation Orientation & Flow Direction
Flow Direction
Every backflow prevention assembly has a designated flow direction marked on the body with an arrow. The assembly must be installed with the arrow pointing in the direction of normal water flow (from supply toward the building). Installing an assembly backward renders it non-functional and creates a false sense of protection.
Check valves are designed to stop reverse flow - if installed backward, they would block normal forward flow instead.
Always Verify Flow Direction
Before testing any assembly, verify the flow arrow on the body matches the actual direction of flow. An assembly installed backward will give abnormal test readings and provides zero backflow protection.
Orientation Requirements
Different assembly types have different orientation requirements:
| Assembly | Horizontal | Vertical (up) | Vertical (down) | Angled |
|---|---|---|---|---|
| RPZ | Yes (most common) | Some models | No | No |
| DCVA | Yes | Some models | Some models | Some models |
| PVB | No | Yes (required) | No | No |
| SVB | No | Yes (required) | No | No |
| AVB | No | Yes (required) | No | No |
RPZ and DCVA assemblies are most commonly installed in a horizontal orientation but some manufacturers approve vertical installation for specific models. Always check the manufacturer's installation instructions for approved orientations.
PVB, SVB, and AVB devices must always be installed vertically (upright) because their air inlet mechanisms rely on gravity to function properly.
Shutoff Valve Requirements
Both the upstream and downstream shutoff valves must be:
- Fully functional - able to completely stop flow when closed
- Accessible for operation during testing
- Resilient seated (rubber or similar) for tight shutoff - many jurisdictions require resilient-seated gate valves or ball valves
Acceptable Shutoff Valves
Ball valves - quarter turn, positive shutoff
Resilient-seated gate valves - rubber seat for tight closure
Butterfly valves - with resilient seat (larger sizes)
Problematic Shutoff Valves
Old brass gate valves - metal-to-metal seats leak
Corroded valves - cannot fully close
Undersized valves - restrict flow excessively
Always verify the flow direction arrow before testing. RPZ and DCVA are typically horizontal; PVB, SVB, and AVB must be vertical only. Both shutoff valves must provide complete, tight shutoff for accurate testing.