Pressure Relief Valve

• Should be removed periodically and checked to ensure they are in working order
• 3 bar discharge pressure for central heating system
• 6 bar discharge pressure for unvented hot water systems
  • push-in type with retaining screw

Reducing Pressure Zone Valve

• Consists of an arrangement of water fittings with three pressure zones incorporating differential actuators that will operate when potential backflow conditions occur or if there is a malfunction of the valve

Non-verifiable Disconnector

• Provides disconnection by venting the intermediate pressure zone of the device to the atmosphere when the difference between the intermediate zone and upstream zone isn't greater than 10% of the upstream pressure

Anti-vacuum Valve

• Has an air inlet which is closed when water in the device is at or above the atmospheric pressure, but opens to admit air if a vacuum occurs at the inlet of the device

Pipe Interrupter

• Air inlet closed by a moving element when the device is in normal use, but which opens and allows air to enter if the water pressure upstream of the device falls to atmospheric pressure

Single Check Valve

• Verifiable single check valve because it has a test port. Allows water to flow from upstream to downstream but not in the reverse

Hose Union Backflow Preventer

• Consist of a single check valve with outlets that open if the water flow ceases