Series 20/21 Resilient Seated Butterfly Valve
The Series 20/21 resilient seated butterfly valve surpasses the high standards required in sanitary valve applications, and inherent flow characteristics and capabilities. Bray's Series 20 valve is a wafer version with flange locating holes, and the Series 21 is the companion lug version for dead-end service and other flange requirements.
- Sanitary & Chemical applications
- High Cv, low pressure drop
Series 20/21 Callouts [A] STEM BUSHING: Non-corrosive, heavy duty acetal bushing absorbs actuator side thrust.
[B] STEM SEAL: Double "U" cup seal design is self-adjusting and gives positive sealing in both directions and prevents external substances from entering the stem bore.
[C] DISC / STEM: One-piece design. The disc edge is spherically machined and hand polished to produce a bubble-tight shutoff, minimum torque, and longer seat life. The disc/stem design inherently provides complete protection from particle entrapment and bacterial decay, protection that is required for sanitary performance. For superior erosion and abrasion resistance, the one-piece disc/stem is fully encased in either EPDM or BUNA-N. The thin disc profile provides a much higher Cv (up to 50% greater than most through-stem designs) and greater pressure recovery, thus resulting in lower pressure drops and a more energy-efficient valve.
[D] PRIMARY & SECONDARY SEALS: These seals prevent line media from coming in contact with the stem or body. Primary Seal is achieved by an interference fit of the molded seat flat with the disc hub. Secondary Seal is created because the stem diameter is greater than the diameter of the stem hole.
[E] SEAT: Bray's tongue and groove seat design lowers torque and provides complete isolation of flowing media from the body. The seat also features a molded O-ring which eliminates the use of flange gaskets.
[F] BODY: Two-piece wafer or lug style allows for ease of assembly and maintenance. Nylon 11 coating for excellent corrosion resistance is standard for 1"-8" valves and available on larger sizes upon request. Polyester coating is standard for 10"-20" bodies.
