RP (Reduced pressure principle backflow preventer); is the highest level of protection by mechanical means, for protection from backflow. May also be called an RPZ or reduced pressure zone assembly.
*This article is only meant as a summary of the testing procedure, you are responsible to test backflow preventers to the standard of your authority having jurisdiction.
RP Testing Steps
- Relief valve – The relive valve must open and dump water at a pressure higher than 2 PSI.
- Check valve #2 – Check valve #2 must close tight in the reverse direction of flow and must hold a differential pressure for 2 min.
- Check valve #1 – Check valve #1 must close tight in the direction of flow and maintain a pressure of at least 3 PSI for 2 min.
- Static line pressure – Record the static water pressure at test cock #1.
RP Maintenance Hints
- Always use the manufacturer’s parts.
- Check valve #1 and #2 are not always interchangeable, even if they look the same.
- Always bleed the test cocks to remove dirt before attaching your gauges.
- Larger devices may have springs under pressure; caution should be taken when performing maintenance.
- Clean in-line strainers
- If the RP is constantly dumping water; close shut off #2, if it continues check valve #1 is likely leaking.
- If removing a backflow device from service place an electrical jumper across the pipe opening first.