Reduced pressure zone device
type of backflow prevention device
A reduced pressure zone device (RPZD, RPZ, or RPZ valve) is a type of backflow prevention device used to protect water supplies from contamination. RPZDs may also be known as reduced pressure principle (RP), reduced pressure principle backflow prevention devices, reduced pressure zone assemblies (RPZA), or reduced pressure principle assembly (RPPA).
ASSE Standard 1013 - Reduced Pressure Backflow Assembly
ASSE Standard 1015 - Double Check Valve Assembly
ASSE Standard 1020 - Pressure Vacuum Breaker
ASSE Standard 1047 - Reduced Pressure Detector Assembly
ASSE Standard 1047 - Reduced Pressure Detector Assembly Type II
ASSE Standard 1048 - Double Check Detector Assembly
ASSE Standard 1048 - Double Check Detector Assembly Type II
ASSE Standard 1056 - Spill Resistant Vacuum Breaker
Backflow preventers are categorized into three groupings: Assembly, Device or Method. With the exception of elimination, these are the only ways one can control backflow from taking place.
The eight named backflow assemblies all have two resilient seated isolation/shut off valves with properly located test ports. These assemblies have the distinct advantage of being in-line serviceable and can be tested & repaired without having to remove an installed assembly. Special accredited courses are given to test & repair backflow assemblies and only certified testers may test backflow assemblies.
There are approximately fifteen devices related to backflow which cannot be tested, as they do not have isolation valves or test ports and there are no standards (test procedures) set in place to test for any device. This is what sets an assembly apart from a device. An assembly is testable, but a device is not.
Begin with the source’s own compact description: “Reduced pressure zone device” is type of backflow prevention device. The dossier treats that line as a proposition to test through Reduced, pressure and zone, not as a finished interpretation.
Why this record matters
The phrase “type of backflow prevention device” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 26, 2025. The linked authority identifier is Q7306333. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1013, 1015, 1020 and 1047.
A concise general-reference account can conceal disagreements about scope, terminology or the weight assigned to individual sources. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Reduced pressure zone device”, its source revision and the description used here.
- Expand the search: follow Reduced pressure zone device primary sources, Reduced pressure zone device archive and Reduced research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Reduced pressure zone device”?
- What terminology or title could unlock a more precise catalogue search?
- Which cited source is closest to the event, object or claim?
Search terms from this dossier
This entry incorporates text from “Reduced pressure zone device” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.