Owner manual
Resilient Seated Butterfly Valves – Torques
All information herein is proprietary and condential 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.
Torque : 13
To Use the Torque Chart, note the following:
1. Dynamic Torque values include all bearing friction and
stem-seal friction torques.
2. Dynamic Torque values are per 1 Bar ∆P. To determine
dynamic torque (N-m) at a desired angle of opening, multiply
the pressure drop ∆P at this angle by the appropriate dynamic
torque factor in the charts below.
3. Bray recommends sizing control valves between 20° and
70°, with 60° the preferred angle.
4. Dynamic Torque will tend to close all Bray valves whose
disc are symmetrical to the stem.
Series 20/21 and 30/31(Dynamic Torque Factor - N-m/bar)
Angle of Opening
10° 20° 30° 40° 50° 60° 70° 75° 80° 90°
Valve
Size
mm
50 0.001 0.001 0.002 0.004 0.006 0.010 0.017 0.024 0.024 0.000
65 0.002 0.002 0.003 0.007 0.011 0.019 0.032 0.046 0.045 0.000
80 0.003 0.003 0.006 0.011 0.018 0.032 0.054 0.078 0.077 0.000
100 0.007 0.007 0.013 0.027 0.043 0.074 0.126 0.181 0.180 0.000
125 0.013 0.014 0.026 0.052 0.083 0.142 0.243 0.349 0.347 0.000
150 0.019 0.022 0.039 0.078 0.125 0.215 0.368 0.528 0.525 0.000
200 0.052 0.053 0.094 0.190 0.304 0.523 0.895 1.283 1.276 0.000
250 0.094 0.104 0.186 0.375 0.600 1.035 1.770 2.538 2.524 0.000
300 0.163 0.181 0.325 0.653 1.046 1.803 3.083 4.422 4.399 0.000
350 0.234 0.260 0.467 0.939 1.504 2.592 4.433 6.358 6.324 0.000
400 0.356 0.396 0.709 1.427 2.286 3.940 6.737 9.662 9.611 0.000
450 0.514 0.571 1.024 2.060 3.301 5.688 9.727 13.950 13.876 0.000
500 0.713 0.792 1.420 2.858 4.578 7.889 13.491 19.340 19.246 0.000
Example: 100 mm Valve; 60° Open with a 10 Bar pressure drop: [Td = (.074)(10) = .74 N-m]
Series 32/33, 35/36 (Dynamic Torque Factor - N-m/bar)
Angle of Opening
10° 20° 30° 40° 50° 60° 70° 75° 80° 90°
Valve
Size
mm
600 1.235 1.372 2.461 4.951 7.931 13.666 23.371 33.517 33.340 0.000
750 2.459 2.733 4.899 9.857 15.791 27.210 46.535 66.738 66.386 0.000
900 4.305 4.783 8.575 17.253 27.639 47.625 81.448 116.808 116.193 0.000
Larger Size Valves - Consult Factory
Example: 600 mm Valve; 60° Open with a 10 Bar pressure drop: [Td = (13.666)(10) = 136.66 N-m]
Dynamic Torque Factors (Metric)