Question:
I am servicing a 4” Ames Model C500. Can you tell me about this assembly and how to change the rubber parts for the checks and relief valve?
Mark:
The Ames Model C500 is a reduced pressure principle detector assembly. Production of this unit started in 2002. The bypass assembly for this model is either an Ames ¾” 400B or a Watts ¾” 919. The check valves for the Ames C500 are modular in design and the relief valve is mounted on the outside of the assembly. To access the checks, remove the #3 test cock by unscrewing it counterclockwise. Removing this test cock will unlock the closure sleeve. Welded onto the closure sleeve, you’ll notice a tab with a hole just the right size for a screwdriver. Place 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. Then slide the sleeve towards the outlet gate valve. With the sleeve out of the way, you will notice that the check modules are secured in the body by a stainless retainer. Simply lift the retainer out of the body.
Doug:
Both check 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. 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. 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. 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 ¼”.
Mark:
Once the spring link has been locked and secured, disconnect the linkage from the spring assembly. To do this, remove the E-clip and hinge pin that joins the two links. With the hinge pin removed, the entire clapper plate will swing freely. There are five Phillip 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.
Doug:
The relief valve will need to be removed from the body to be serviced. The RV body is threaded onto the body and sealed by an o-ring. Disconnect the sensing line and unscrew the body. Once the RV has been removed, remove the four Allen screws that secure the cover plate. With the cover removed, the diaphragm will pull away from the top of the piston. The next step is to release the spring tension so that piston and disc can be serviced. With the threaded end facing up, push up on the piston until the shaft with the attached E-clip is exposed. Once the E-clip is removed, the piston and spring are free. The RV disc is a molded part of the stainless piston. If there is damage to the disc, the piston must be replaced. Reassemble the RV in reverse order. It is important to remember to form the diaphragm to fit neatly over the piston before replacing the cover.
