This is a double check assembly. Production began in 2018. The body is stainless steel and configured in an angle pattern. The normal installation orientation in the ST models allows water to come up from the bottom and then go through two 90 degree turns and then goes into a downward flow. This is commonly called a N pattern installation. The STV model allows for a vertical orientation. This can happen when the downside 2nd check body is rotated 180 degrees. This allows the flow of water to come up from the inlet check and then rotate the outlet so it goes into an upward flow. The STR model has a spool placed between the two check bodies making an adjustable center to center dimension. This allows for a retrofit installation. The rubber repair parts are the same in all 450ST versions. There is a separate check cover for the inlet and outlet check. The cover is attached to the body by a grooved coupling. When the cover is removed the springs are contained. On the 4"-6" sizes the checks are held into the body by a plastic retainer. By squeezing the retainer it can be released and removed, then the Noryl plastic check can be pulled from the body. The modular check is sealed into the body by an O'ring. The 8"-10" size checks are held in by 6 bolts rather than a retainer clip. Once the Noryl plastic check module is removed there are bolts on the back side that can be removed to access the check disc. Spring tension is contained and does not need to be released. If more than the rubber check disc is needed for repair, the check module will need to be replaced.
Common repair parts are a very small subset of the 10,000 plus items BAVCO stocks.
Please feel free to contact us direct at 800-458-3492 for pricing on items not listed
or backflow prevention devices.