Bray 31U - Manual (Page 6)

Resilient Seated Butterfly Valves – Torques
All information herein is proprietary and confidential and may not be copied or reproduced without the expressed written consent of BRAY INTERNATIONAL, Inc.
The technical data herein is for general information only. Product suitability should be based solely upon customer’s detailed knowledge and experience with their application.
Introduction : 6
Reduced Disc Diameter
Bray Series 30/31/3A Valves
Bray offers a reduced disc diameter for 4”-20” for Series 30, 31
and 3A valves. The purpose of reducing the disc diameter is to
decrease the seating/unseating torques and extend the seat life on
low pressure applications.
By reducing the disc diameter, the interference between the disc
O.D. and seat I.D. is decreased and the valve pressure rating,
which is a function of this interference, is reduced to 50 PSI. Less
interference between the disc and seat results in reduced seating/
unseating torques. Lower seating/unseating torque may allow for
the use of a smaller actuator on the valve. In other applications
where abrasive dry bulk materials such as cement, sugar, plastic,
pellets, flour, etc., are generally pneumatically conveyed at 50
PSI or less, the reduced disc diameter not only reduces the seat-
ing/unseating torque but, very importantly, usually significantly
increases the service life of the seat.
Bray does the following to differentiate reduced diameter discs
from full diameter discs:
Metal Discs: An “ R ” is stamped above the part number
Nylon 11 Coated Discs: Discs are differentiated by the color of
the Nylon 11:
Grey – Full Disc Diameter
White – Reduced Disc Diameter