How does the general vavle work?

When the valve is fully opened, the channel of plug is in alignment with the channel of valve body, which can ensure ideal and lowest pressure drop.
When the handwheel is turned, the plug will rotate toward the closing direction ,and at the same time draft the rotation of valve disc by 90°，when the handwheel is turned further on, the plug will be pressed down. and make the valve disc open to two sides. so that the valve disc will be in firm contact with the valve seat and close the valve.
The advantage of this type of valve is,during the opening and closing of valve,the disc and valve seat is separated,and there is no friction and thus sealing face is no abrasion in the process;at the same time ,soft seal is applied for sealing ,so that there will be no leakage in the process of closing.
When the handwheel is turned inversely, first of all the plug will move upward, and the valve disc and valve seat will be separated, if the hand wheel is turned further on,till the valve disc is turn the valve disc is turned by 90° driven by the plug. and finally the channel of plug will be in alignment with the channel of valve body,so that the valve is be fully opened.
the advantage of this type of valve is during the opening and closing of valve, the disc and valve seat is separated,and there is no friction and thus sealing face is no abrasion in the process.At same time, soft seal is applied for sealing ,so that there will be no leakage in the process of closing.