How To Repair Wilkins Backflow Preventer

I take to repair a one″ Wilkins 720A. Can you lot tell me if there are whatsoever special tools that I'll need, or any helpful hints that will help with this repair?

Doug:

Before we go over the repair steps, let'due south take a quick wait at this unit. The Wilkins 720A is a pressure vacuum breaker that is offered in ½"- 2" sizes. The original version began production in 1975 as the model 720. In 1984, Wilkins redesigned the air inlet valve and the model number became 720A. The "A" air inlet valve will work for both the 720 and 720A. Prior to 2022, the exam cocks were located on the body of the assembly. Later 2022, the test cocks were located on the ball valves. Fortunately, no special tools are needed to work on this unit; you should only need a Phillips-caput screwdriver, a 7/16" wrench and a xi/32" socket.

Mark:

Get-go we demand to remove the 3 screws that secure the black plastic canopy to the bonnet. The bonnet is bronze, threaded into the body and sealed by an o-ring. To help loosen the bonnet, place a screwdriver on the three brass pegs and turn counter clockwise. Once the bonnet is off, y'all can remove the plastic washer and bonnet o-ring. The poppet assembly is free one time the bonnet is
removed. To supersede the rubber on the poppet assembly, use a 7/16" wrench to remove the guide pin and nut. Make sure that when you replace the disc, the ridges are facing up toward the guide pin. The metal washer should fit snuggly inside the ridges of the disc. At present nosotros will work on removing the check valve associates.

Doug:

The check valve assembly is leap loaded. The spring is held in place by a brass lip on the inside of the body. Getting the bound out can be a little tricky. We found the easiest fashion is by compressing the spring downwardly on one side – this should cause the bound to pop upward over the brass lip. At that place will even so exist some tension on the spring, but it is prophylactic to pull it out. Once the bound has been removed, we can turn our attending to the bank check valve poppet (i.eastward. the spider assembly).

Marking:

The spider assembly is costless once the leap is removed. The safety disc on the spider assembly is held in place by a nut and screw. Employ a 11/32" socket to concur the nut while you lot remove the spiral. When reassembling the spider associates, make sure the plastic guide is on the flat side of the safety disc. Before y'all supercede the spider assembly, be sure to audit the contumely seat. The seat is part of the trunk and is not replaceable. If the seat is damaged, the entire associates must be replaced. Now you tin just reassemble the unit in reverse society.

Source: https://backflowparts.com/wilkins-720a-how-to-repair/

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