Pressure Vacuum Breaker (PVB)
Spill Resistant Vacuum Breaker (SPVB)
Spill Resistant Vacuum Breaker (SPVB)
A pressure vacuum breaker contains:
- A spring-loaded check valve
- An air inlet valve
- Shutoff valves and test cocks for testing
Under normal water pressure:
- The check valve remains open
- The air inlet valve stays closed
If supply pressure drops or a vacuum condition occurs:
- The check valve closes
- The air inlet opens to atmosphere
- Air enters the system to break the vacuum and stop contaminated water from being siphoned backward
Spill Resistant Vacuum Breaker (SPVB)
Spill Resistant Vacuum Breaker (SPVB)
Spill Resistant Vacuum Breaker (SPVB)
An SVB contains:
- A spring-loaded check valve
- An air inlet valve
- Internal components designed to reduce vent spillage
- Test cocks and shutoff valves
During normal operation:
- Water pressure keeps the air inlet closed
- The check valve remains open for water flow
If a vacuum or negative pressure condition occurs:
- The check valve closes
- The air inlet opens
- Air enters the system to break the siphon and prevent contaminated water from being drawn into the potable supply
Double Check Assembly (DC)
A double check assembly contains:
- Two independently operating spring-loaded check valves
- Shutoff valves on each end
- Test cocks for inspection and testing
Water flows in one direction through both check valves. If water pressure reverses, the check valves close to prevent contaminated water from flowing backward into the clean water supply.
Unlike an RP assembly, a DC assembly does not have a relief valve.
Reduced Pressure Assembly (RPZ)
An RP backflow preventer contains:
- Two independently acting check valves
- A pressure-monitored relief valve located between the checks
- Shutoff valves and test cocks for inspection and testing
The device maintains a pressure zone between the two check valves that is lower than the supply pressure. If either check valve fails or pressure reverses, the relief valve opens and discharges water to prevent contaminated water from flowing back into the potable water supply.