A lightweight butterfly valve having a disk maintained in a fixed position on a compound shaft through an interlocking relation ship between each of the individual shafts of the compound shaft and the disk as the disk is moveable between an open or closed position with the butterfly valve may having other features such as an electric drive to quickly rotate the compound shaft to provide for rapid opening and closing the butterfly valve, a disk position indicator and a shaft stop to prevent the disk from being driven past a full open condition.

A structure of gas regulator comprises a space for setting an intake switchover valve formed at an outer end of a high-pressure portion and interconnected with the inside of the high-pressure portion. A pushing block is outside a diaphragm, and an elastic element is set between the pushing block and a flange at the periphery of an inner end of the pushing block. A support base outside the pushing block is abutted the elastic element and comprises an extending section extended from an inner end thereof and corresponding to the outer periphery of the elastic element and a through-hole corresponding to the pushing block. A display diaphragm with a center slot is outside the support base. A cover covered the space has a transparent side display window at the periphery thereof and a transparent outer display window at an outer end thereof.

Three-way valve with two flaps comprising single control means (9) for the two flaps and actuation means (12, 13, 50) arranged each to drive, pivotwise, one of the two flaps, from one to the other of its open and closed position of one of the pathways, with a temporal phase-shift, characterized in that it comprises maximum displacement end-stops for each of said actuation means, the end-stop (31) of the second actuation means (12, 50) corresponding to a fully closed position of its flap and the end-stop of the first actuation means (13) being positioned beyond the position of said first actuation means when the second actuation means (12, 50) is on its end-stop (31), the kinematic chains linking the first and second actuation means to the single control means operating nominally.