Which backflow assembly is approved for high-hazard connections, protecting against both backpressure and backsiphonage?
Not quite. The answer is D: Reduced pressure principle (RP) backflow preventer
The RP assembly's independently-acting check valves plus a relief valve venting to atmosphere protect against both hazard directions at once and fail visibly rather than silently — the only device on this list rated for genuinely high-hazard service.
Checked against the 2021 UPC text. Washington's exam is written against the 2015 edition, which we have not read for this section, so confirm it against your 2015 book.
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