Watts 757DCDA: How To Repair
The check valve for the Watts 757DCDA is modular in design. It utilizes a “Tri Link” mechanism between the spring assembly and disc retainer. The spring tension must be relieved to replace the check rubber.
Before we go over the check repair of the Watts 757DCDA, we should briefly go over the access and removal of the check valves. After closing both gate valves and bleeding any excess pressure through the test-cocks, remove the #3 test-cock by turning counterclockwise. Removing this test-cock will unlock the closure sleeve.
Welded onto the closure sleeve you’ll notice a tab with a hole. Place the shaft of a screwdriver through the hole in the tab and using your screwdriver as a handle, rotate the closure sleeve 90 degrees in both directions to break the O-ring seal, and then slide the sleeve towards the outlet gate valve. With the sleeve out of the way we can now remove the check retainer.
The check modules for the Watts 757DCDA are secured in the body by a stainless retainer. Simply lift the retainer out of the body. Both check modules are sealed with an O-ring and slide into the body. You will notice two notches in the first check valve. Place the tip of a slotted screwdriver in these notches and slide the check valve out of the body. With the first check valve in hand, clean or replace the seat O-ring. If you’re looking at the inlet end of the check, you’ll notice the spring assembly and linkage. One link is attached to the disc retainer and one is attached to the spring assembly. Here is where we want to lock the spring link in place.
To do this you’ll need a 1/2-inch-13 fully threaded hex head bolt at least 5 inches long. Locate the threaded hole adjacent to the spring linkage and thread the bolt into the hole until it comes in contact with the spring link. Using a wrench, continue to thread bolt in until the hole in the spring link is aligned with the notches on the spring arbors. Slide a Phillips screwdriver through the arbors and the hole in the spring link making sure that the tip of the screwdriver extends past the ends of the arbors by at least a 1/4”. Now back the 1/2” bolt out until the spring load is placed on the screwdriver. Note that at this point, the spring assembly can slide out of the check body. With 4” and smaller sizes the spring assembly can unload if it is removed. So, take care and don’t remove if possible.
Once the spring link for the Watts 757DCDA has been locked and secured, we must disconnect the linkage from the spring assembly. To do this we need to remove the “E” clip and hinge pin which joins the two links. With the hinge pin removed, the entire clapper plate will swing freely. There are (7) Philips head screws that secure the disc retainer to the clapper plate. The check rubber is free and can be replaced once the disc retainer has been removed.