QUESTION:
I have a 2-inch Watts 007DCDA on a fire system that needs to be serviced. This is the first time I have worked on this model. Can you tell me how to properly service the check valves for this assembly?
MARK:
The 2-inch Watts 007DCDA is a double check detector assembly. It utilizes a ½-inch model 007 DCA for a bypass assembly. The bypass arrangement also contains a 5/8-inch-by-¾-inch bypass meter. Production of the original unit began in 1998. The model 007DCDA(M1) was introduced in 2011. The changes were to the device body and the bypass piping. The repair procedures and replacement parts are the same for both assemblies. There are no special tools needed to make this repair.
DOUG:
The main line assembly has a single access cover that is O-ring sealed and is secured by six hex head bolts. There is no spring load on the cover. Once the cover is removed, the check modules and retainer are visible. The check valve modules are sealed by an O-ring and secured by a retainer. The stainless steel retainer should slide straight up and out of the body. To remove the first check module, simply grasp the spring retainer (cage) and pull it straight out of the body. To remove the second check module, use a flathead screwdriver to help pry it straight out of the body.
MARK:
Be aware that each of the check modules is spring loaded. To service the modules, we will need to release the spring tension. The spring is held in place by a plastic retainer, or cage. The retainer is attached to the seat with a bayonet locking system. Hold the cage firmly in one hand, push the seat inward with the other hand and rotate clockwise approximately one-quarter turn. Note: It will not release if turned counterclockwise. Once it is unlocked, the spring, poppet and seat are free for inspection or replacement.
DOUG:
Reassembly and installation of the checks will be in reverse order. Remember when replacing the stainless steel retainer that it must slide into place easily. If it does not, then the check modules are not fully seated into the body. If you are also servicing the ½” bypass assembly, then the repair procedures will be the same as the mainline unit. The main difference in the check modules is that they are very small and snap apart instead of using a bayonet locking system.
