Tips and Notes

Gear-driven valve vs. handwheel valve with rising stem

The handwheel or lever on manually operated valves is designed so that reasonable effort by the operator(s) is sufficient to operate the valves. MSS SP-91: Guidelines for Manual Operation of Valves provides recommendations in this regard. This standard defines an operator as a person who can apply approximately 670 N (150 lbf) of force to a lever with an effective length of 300 mm (12 inches).