What it is
The Apollo RPLF4A in 2½" through 12" (part numbers in the 4ALF-200 series) is the company's current large reduced pressure zone assembly: 304 stainless body through 8", epoxy-coated ductile iron at 10" and 12", a bottom relief valve with its own center access cover, and NRS, OS&Y, or butterfly shutoffs. The RPDALF4A (4ALF-700) is the detector version; the DCLF4A (4ALF-100) is the double check in the same body.
It replaced the Conbraco 40-200 series, a much longer ductile-iron wye body. A cover built for a 40-200 is badly oversized on a 4ALF-200.
Length runs 31" at 2½", 37⅗" at 4", 45½" at 6", 53" at 8". The relief valve hangs 9" below the pipe at 2½" and 3", 9⅘" at 4", 11" at 6", 15⅘" at 8", and 21" at 10".
What matters for the cover
Length lines up with the Zurn 375. At 2½" through 6" the Apollo and the flanged Wilkins 375 are within an inch of each other, so the same price-list covers apply: 70 × 40 at 3", 85 × 40 at 4", 100 × 50 at 6".
Depth grows fast. Nine inches of relief valve at the small end is ordinary; 15⅘" at 8" and 21" at 10" is the deepest in this category. The 50" and 55" cover heights on the 120 × 50 and 130 × 55 were built with this stack in mind, but riser height matters more here than on any other large RP. Photos on 8" and up.
Relief discharge. The relief valve under the body has to drain. Set the cover so the base closes to the pad around the assembly but never seals under the relief port.
RPDALF4A. The bypass and meter sit beside the mainline and push total width to 17"–27½". Photos first on every detector size.
Stocking
Apollo's large RP is on commercial domestic and fire service across the Southeast. Plumbing houses see 2½" through 4" and stock the 70 × 40 and 85 × 40; fire protection distributors see the RPDALF4A at 4" and 6". Same covers fit the DCLF4A double check size for size.