Backflow Reference Manual - Febco

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850 / LF850 / 850B / 850U / 870 / 870V / LF870V


1/2", 3/4", 1", 1 1/4", 1 1/2", 2", 2 1/2", 3", 4", 6", 8", 10"


This is a double check assembly. The 1/2"-2" sizes began production in 1997. The body is made of bronze and utilizes an in-line modular check design. In 2010 the 850LF was introduced in sizes 1/2"-2" constructed of lead free bronze. The check modules are made of glass filled noryl and held in the body by a retainer. The model 850U incorporates a union end ball valve on the model 850. In 2000 the model 850B was developed as a bypass for the model 831, 856, and 876. Production on sizes 2 1/2"-10" began in 1993. The body is made of ductile iron which is fused epoxy coated. Check springs are contained when the cover is removed. Check seats are replaceable. The internal check mechanism is a swing check design with the internal parts made mostly of bronze. The check disc utilizes a vulcanized clapper plate design of elastomer seal. The difference between the models is in the shape of the body. The 850 model is a straight horizontal configuration. The 870 is known as the N shape. The piping comes up from the bottom on the inlet and goes down out of the outlet to give it a compact installation feature. The 870V is a vertically oriented assembly where the piping comes up into the inlet and then goes horizontally through the check mechanism. The outlet continues to go up out of the outlet check to give it a vertical orientation. In 2011 the LF 850 and LF 870V were introduced. The internal check mechanism was changed to a lead free design. The previous leaded bronze items were changed to stainless steel or other lead free materials. The internal check utilizes a silicone disc instead of the vulcanized clapper plate as in the earlier 850, 870, and 870V design.


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.