DCVA (double check valve assembly) - is a backflow preventer suitable for a moderate hazard. The DCVA is an excellent backflow preventer, but unlike the RP(reduced pressure zone assembly), it does not visibly show when it has failed, so it cannot be used on a severe hazard and must be tested at least annually.
*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.
Reduced Pressure Zone - Testing Steps
- Check valve #1 - must remain closed in the direction of flow for 2 min, and have an inlet pressure 1 PSI higher than the outlet pressure.
- Check valve #2 - must remain closed in the direction of flow for 2 min, and have an inlet pressure 1 PSI higher than the outlet pressure.
- Static line pressure - you must record the static water pressure at the time of the test from test cock/port #1.
Double Check Valve Assembly - Maintenance Hints
- Always use manufacturer's replacement 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 removing a backflow device from service place an electrical jumper across the pipe opening first.