The structural difference between diaphragm valve and globe valve

2024-01-22

A globe valve refers to a valve in which the closing member (valve disc) moves along the centerline of the valve seat. According to this movement form of the valve disc, the change of the valve seat opening is proportional to the valve disc stroke. Since the stem opening or closing stroke of the stop valve is relatively short and has a very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating flow. Therefore, this type of valve is very suitable for shutting off or regulating and throttling.

Advantage of globe valve:

① During the opening and closing process, because the friction between the valve disc and the valve body sealing surface is smaller than that of the gate valve, it is wear-resistant.

②The opening height is generally only 1/4 of the valve seat channel, so it is much smaller than the gate valve;

③ Usually there is only one sealing surface on the valve body and valve disc, so the manufacturing process is relatively good and it is easy to maintain.

④ Since its filler is generally a mixture of asbestos and graphite, it has a higher temperature resistance level. Generally, stop valves are used for steam valves.

Shortcoming of globe valve:

①Due to the change in the flow direction of the medium through the valve, the minimum flow resistance of the stop valve is also higher than that of most other types of valves;

②Due to the longer stroke, the opening speed is slower than that of the ball valve.

Diaphragm valve refers to a flexible membrane or combined diaphragm installed in the valve body and valve cover, and its closing member is a compression device connected to the diaphragm. The valve can be in the shape of a weir, or it can be a pipe wall that leads directly to the flow channel.

Advantage of diaphragm valve:

① The operating mechanism is separated from the medium passage, which not only ensures the purity of the working medium, but also prevents the possibility of the medium in the pipeline impacting the working parts of the operating mechanism. There is no need to use any form of separate sealing at the valve stem unless harmful media are being controlled. used as a safety device;

② Since the working medium only contacts the diaphragm and the valve body, both of which can be made of a variety of different materials, the valve can ideally control a variety of working media, especially suitable for media with chemical corrosion or suspended particles.

③Simple structure, consisting of only three parts: valve body, diaphragm and valve cover assembly. The valve is easy to quickly disassemble and repair, and diaphragm replacement can be completed on site and in a short time.

Shortcoming of diaphragm valve:

① Due to the limitations of the valve body lining process and diaphragm manufacturing process, the manufacturing process of larger valve body lining and larger diaphragm is difficult, so the diaphragm is not suitable for larger pipe diameters and is generally used in pipes with DN≤200mm. On the pipeline.

② Due to the limitation of diaphragm material, diaphragm valve is suitable for low pressure and low temperature situations. Generally not exceeding 180℃;

③The adjustment performance is relatively poor and can only be adjusted within a small range (generally when it is closed to 2/3 of the opening, it can be used for flow adjustment).

Pre : What is an oval gear flowmeter?

Next : 9 common misunderstandings in gate valve installation