a) Measurement by torque wrench

b) Measurement by lever and spring balance

l (mm) F (N) Md = F * l / 1.000 [Nm]

c) Calculation based on hand wheel diameter

ØD (mm)	Md
für ØD < 200 (one hand operation)	Md = ØD * 0,18 [Nm]
für 200 < ØD < 800 (two hand operation)	Md = ØD * 0,40 [Nm]
für ØD > 800 (two man operation)	Md = ØD * 0,70 [Nm]

d) Torque derived from spindle dimensions

Outside spindle diameter da	Torque Md
da < 26 mm	Md < 60 Nm
28 mm < da < 32 mm	60 Nm < Md < 120 Nm
30 mm < da < 40 mm	120 Nm < Md < 250 Nm
36 mm < da < 44 mm	250 Nm < Md < 500 Nm
44 mm < da	500 Nm < Md

When identifying the torque requirements it has to be taken into account that the differential pressure as well as the frequency of operating the valve (c/h) influences torque requirements. Shut-torque values are normally lower than opening- or break-off-torque's, caused by differential pressure and/or thermal distortion.