Abstract
The conventional pneumatic control valves are inferior to other control components in the static and dynamic characteristics because of followings:(1) Friction at gland packings, (2) Undesirable characteristics induced by springs and (3) Inaccurate shape of inner valves.
The author examined some glandless control valves of which principle was similar to that of commonly used pilot valves. They were superior to the usual control valves in the above characteristics, besides were able to be made more compactly and economically. Some discussion on the limitations in their application were also given.
