Question:
I have a 4” Deringer Model 40. Can you tell me how to change the rubber parts for the checks and relief valve? Are special tools needed to service this assembly?
Mark:
The Deringer Model 40 is a reduced pressure principle assembly. Production began in 2014 and the check valves for this model are modular in design. There are no special tools needed to service this assembly. The access cover is secured by six bolts and sealed by an o-ring. There is no spring load on the cover. When removing the bolts, you will notice the bolts have washers that are tapered. These unique washers are needed to help make a water-tight seal on the access cover. The check valve modules are secured in the body by retaining bolts located on the outside of the valve body.
Doug:
There are three retaining bolts on either side of the valve body. Loosen each of the 7/32” Allen retaining bolts until they are flush with the inner wall of the body. The check valve modules are sealed with an o-ring and slide into the body. The first check must be removed before the second check can be removed. Using a flat blade screwdriver, gently
pry each module out of the body.
Once the check modules are removed from the body, the check tower can be disassembled from the seat. To do this, remove the four tower screws located on the seat side of the first check module and the downstream side of the second check module. The torsion spring is captured and does not need to be retained. With the tower screws removed, the seat is free and can be inspected. The check seat is part of the module. If the seat is damaged, the entire module will have to be replaced. To replace the check disc, simply remove the six retaining screws from the disc retainer. The disc is free and ready for replacement.
Mark:
When reassembling the first check valve, simply replace the four tower screws on the seat side of the module. When reassembling the second check valve, it is important to remember that the tower and seat orientation is critical for proper check operation. The proper orientation is achieved when the spring arms on the tower are facing DOWN and the seat protrusions are facing UP. When reinstalling the modules, check #2 must be installed before check #1. Once the modules are fully seated, tighten the six retaining Allen bolts on the outside of the body. Make sure that the retaining bolts do not bind against the check towers. The last step is to secure the access cover on the main body. Be sure to install the tapered washers in the correct position on the bolts. It is also important to tighten the cover bolts sequentially and by alternating from side to side.
Doug:
The relief valve must be removed from the body to be serviced. It is bolted to the body and sealed by an o-ring. Disconnect the sensing line first and then remove the retaining bolts. Once the RV body has been dismounted, remove the four cover plate screws and diaphragm. Next, the spring load must be discharged. To do this, push the piston with your thumb toward the threaded side of the housing until the shaft with the attached E-clip is exposed. Hold the piston firmly as the E-clip is removed and the spring tension is released. The piston assembly and spring are free once the spring tension is fully released. The RV disc is molded onto the piston assembly and must be replaced as one piece. The RV seat is a machined part of the housing, so if there is any damage the housing must be replaced. Reassemble the relief valve in reverse order and reattach the complete RV to the body.
