Backflow Reference Manual - Backflow Direct

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Magnum 40 / 40G



This is a reduced pressure assembly. Production began in 2018. The model 40 come with grooved end integral butterfly shut offs while the 40G comes with NRS flanged end shut offs. The body is a fabricated stainless steel design with a bolted single access cover. The checks are a modular design made of Noryl plastic material. The check discs are silicone rubber. The check modules are held into the body with bolts that extend from the outside of the body into a slot to hold the check modules in place. These allen head bolts have to be unscrewed to remove the check modules from the body for repair. The check uses a torsion spring design. Spring tension does not need to be released to change the check disc. The relief valve uses a stainless steel body that screws onto the bottom of the check body and uses an external relief valve sensing line. The relief valve uses a rolling diaphragm design with a silicone disc. The relief valve spring is contained when the relief valve cover is removed and is released by the removal of an e-ring on the relief valve stem.


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.