Installation Requirements and Site Surveys
Installation essentials
Correct installation determines whether an approved assembly actually protects. Key requirements: orientation per the manufacturer (horizontal or vertical), adequate clearance for testing and repair, proper elevation (PVB above the highest downstream outlet), drainage for RP relief discharge, and protection from freezing, flooding, and vandalism. Assemblies must be accessible for testing and located where discharge will not cause damage. Know local requirements for pit installation, strainers, and bypass lines.
Site surveys
A site survey identifies every actual and potential cross-connection. Surveyors trace the potable system, catalog fixtures and equipment (carbonators, boilers, irrigation, chemical injection, hose bibbs), classify each hazard, and recommend containment and isolation protection. Document with a sketch, photographs, and a hazard inventory. Traps: missing hidden connections (fire sprinkler systems, cooling towers, laboratory lines), misclassifying hazard level, and recommending an assembly that cannot be installed at the required elevation or drainage.
Traps in questions
Watch for orientation errors, PVB installed too low, RP without a drain, and assemblies in inaccessible vaults. Also watch confusion between required containment at the service and optional isolation inside.
Rule of thumb
Before approving an installation, confirm four things: correct assembly for the hazard, correct orientation, adequate clearance, and a safe discharge/drain path.
Worked example: A proposed PVB for irrigation is mounted below the highest sprinkler head. It fails installation requirements - raise it above the highest outlet or select a different assembly.