Wilkins 420 Pressure Vacuum Breaker Assembly

About Vacuum Breakers

• Pressure vacuum breakers, such as the Wilkins 420, are designed to prevent water that enters an irrigation system from flowing back into the main water line. This is important for safety of the drinking water inside the house, because water that enters irrigation pipes is exposed to chemicals and volatile organic compounds from the irrigation pipes and chemical cement that can make people sick. For this reason, water that enters an irrigation system is no longer considered to be potable, or drinkable.

Installing the Wilkins 420

• When installing the WIlkins 420, it's critical that the unit be installed at an elevation that's at least 12 inches higher than the highest sprinkler on the system. That's because pressure vacuum breakers rely on differences in air pressure to keep water flowing only in one direction. The Wilkins vacuum breaker should only be installed in a vertical position on pipes that are rated for compression fittings, such as copper or rigid PVC. The Wilkins 420 contains two ports for attachment to pipes. These are marked "inlet" and "outlet" to ensure the proper directional flow of water. To connect the breaker to the pipes, position the body of the Wilkins 420 over the inlet and outlet pipes on the sprinkler system, and align the compression fittings on the bottom of the body with the inlet and outlet pipes. Press down on the body so that the pipes are forced about 1 inch into the compression fittings. Tighten the compression nuts around each fitting using an adjustable wrench to secure the pipes to the breaker. Turn on the water to the sprinkler valves to charge the breaker. A small amount of water may squirt from the top of the bonnet as the line pressurizes.

Draining the Wilkins 420

• When winter comes, it's important to remove as much water as possible from the inside of the vacuum breaker. Frozen water can burst the brass fittings or break internal components such as springs and bonnets. To remove water, turn off the main water line to the sprinklers. and open both the inlet and outlet drain valves in the system. Open the inlet and outlet shut-off valves, as well as the test cocks on the side of the valve. Leave all valve handles at a 45-degree angle during the winter. This will leave room for any remaining water to expand and escape the valve without causing damage.

Maintenance

• The Wilkins 420 contains a few internal components that should be cleaned and inspected annually. Remove the canopy screw and canopy to access the internal components. Remove built-up water pressure by opening the test cock that's farthest down on the side of the valve. Remove the bonnet from the inside of the valve by unscrewing it counterclockwise. Reach inside the valve body and pull out the float assembly, spring retainer, spring, O-ring and spider. Run each of the parts under cold water, and rub clean with your fingers or a soft sponge. Remove as much algae or slime build-up as possible to ensure a steady flow of water.