01. Structurally
When the installation space is limited, you should pay attention to the selection:
The gate valve can be tightly closed with the sealing surface by the medium pressure and tightly closed to achieve a non-leakage effect. During valve opening and closing, the sealing surface of the valve plug and the valve seat always contact and rub against each other, so the sealing surface is easy to wear, and when the gate valve is close to close, the pressure difference between the front and the rear of the pipeline is large, and the sealing surface wear is more serious.
The structure of the gate valve is more complicated than that of the globe valve. From the aspect of the shape, the gate valve is higher than the globe valve in the same diameter, and the globe valve is longer than the gate valve. In addition, the gate valve has a rising stem or non-rising stem, which the globe valve does not have.
02. Working principle
When a globe valve is opened and closed, it is a rising stem type. That is to say, turning the hand wheel, the hand wheel will rotate and lift together with the valve stem. Whereas, for gate valves, hand wheel is rotated in order that the valve stem can rise and fall, and the position of the hand wheel itself is unchanged.
Flow rates vary, gate valves are required to be fully open or fully closed, while globe valves are not required. For globe valves, there are specified inlet and outlet directions, and the gate valve has no requirements for inlet and outlet.
In addition, the gate valve has only two states of full opening or full closing, the stroke of the shutter opening and closing is large, and the opening and closing time is long. The valve plate movement stroke of the globe valve is much smaller, and the valve plate of the globe valve can be stopped at a certain position during the movement for flow regulation. The gate valve can only be used for cutting off and has no other functions.
03. Performance difference
The globe valve can be used for both cut-off and flow regulation. The fluid resistance of the globe valve is relatively large, and it is laborious to open and close. However, since the distance between the valve plate and the sealing surface is short, the opening and closing stroke is short.
Because the gate valve can only be fully open and fully closed, when it is fully open, the medium flow resistance in the valve body passage is almost zero, so the opening and closing of the gate valve will be very labor-saving, but the disc is far away from the sealing surface, and the opening and closing time is long.