Globe Valve
A globe valve is a type of valve in which the closing element (valve disc) moves along the centerline of the valve seat. This movement directly correlates the change in the valve seat opening with the valve disc's stroke. Because globe valves have relatively short opening and closing strokes, excellent shut-off capability, and a direct correlation between the valve seat opening change and the valve disc stroke, they are ideal for flow regulation. In general, globe valves are ideal for applications such as shut-off, regulation, and throttling.
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GNEE Globe Valve Drawning,Send us your valve drawings and we'll customize it for you.
Advantages:
During opening and closing, the friction between the valve disc and the valve body sealing surface is relatively low, resulting in good wear resistance.
The opening height is typically only about one-quarter of the valve seat passage, making operation easier compared to gate valves.
Globe valves usually only have one sealing surface on the valve body and valve disc, simplifying the manufacturing process and facilitating later maintenance.
The packing used in globe valves is often a mixture of asbestos and graphite, which gives them a relatively high temperature resistance, making them commonly used in the manufacture of steam valves.
Disadvantages:
Because the flow direction of the medium changes when passing through a gate valve, its minimum flow resistance is higher compared to other types of valves.
Also, due to the longer stroke of a gate valve, its opening speed is slower than that of a ball valve.
Diaphragm Valve:
A diaphragm valve is a special type of shut-off valve. Its key component is a diaphragm made of a soft material. This diaphragm effectively isolates the valve body cavity from the valve cover cavity and the drive components, ensuring unidirectional fluid flow through the valve. Diaphragm valves have a simple structure, low fluid resistance, and a stronger flow capacity than other types of valves of the same specifications. Furthermore, due to its unique structural design, diaphragm valves are leak-free, making them ideal for regulating high-viscosity media and media containing suspended particles.
However, the pressure and temperature resistance of diaphragm valves are limited by the performance of the diaphragm and lining materials, generally only suitable for nominal pressures below 6 MPa and temperatures below 150°C. Its flow characteristics are close to quick-opening characteristics, approximately linear before 60% of the stroke, with relatively small flow changes after 60%.
In addition, pneumatic diaphragm valves can be equipped with feedback signals, limit switches, and positioners to meet the needs of automatic control, programmable control, or flow regulation. This product uses a diaphragm-type propulsion cylinder instead of a traditional piston cylinder, effectively avoiding leakage problems caused by piston ring damage.
Furthermore, even in the event of a pneumatic failure, the operator can still control the valve's opening and closing via handwheel.
The valve body of the diaphragm valve is typically made of cast iron, cast steel, or cast stainless steel, and is equipped with various corrosion-resistant or wear-resistant materials. The diaphragm material is made of rubber and polytetrafluoroethylene (PTFE), both of which have excellent corrosion resistance and are particularly suitable for regulating highly corrosive media such as strong acids and alkalis. Furthermore, the diaphragm valve has a simple structure, low fluid resistance, stronger flow capacity, and leak-free characteristics, allowing it to maintain stable performance even under high pressure and high temperature environments.
GNEE diaphragm valve drawning, Send us your valve drawings and we'll customize it for you.
Advantages:
The diaphragm valve's operating mechanism is completely isolated from the media passage. This design not only ensures the purity of the working medium but also prevents the impact of the medium in the pipeline on the working parts of the operating mechanism. Furthermore, no separate seal is required at the valve stem, except in safety installations controlling hazardous media.
Since the working medium only contacts the diaphragm and valve body, both of which can be made from a variety of different materials, diaphragm valves can ideally control a wide range of working media, especially those containing chemical corrosives or suspended particles.
The diaphragm valve has a very simple structure, consisting of only three components: the valve body, the diaphragm, and the valve cover assembly. This design allows for easy and quick disassembly and maintenance, and diaphragm replacement can be completed in the field in a short time.
Disadvantages:
Due to limitations in valve body lining and diaphragm manufacturing processes, manufacturing larger valve body liners and diaphragms presents challenges. Therefore, diaphragm valves are generally not suitable for larger pipe diameters, and their application is typically limited to pipelines with DN ≤ 200 mm.
Diaphragm valves are limited by the diaphragm material and are suitable for low-pressure and low-temperature applications, generally not exceeding 180°C.
In terms of regulation performance, diaphragm valves are relatively poor, mainly used for regulation within a small range (typically, flow regulation can be used when closed to 2/3 of the opening).
Differences between Diaphragm Valves and Globe Valves
Based on the above introduction to the principles, structures, and operating methods of diaphragm valves and globe valves, we can draw the following conclusions:
1. Different Principles and Structures: Diaphragm valves use a diaphragm to control the flow of media, while globe valves use a valve opening and closing mechanism to control the flow of media.
2. Different Applications: Diaphragm valves are suitable for media containing particles, high viscosity, or strong corrosiveness; globe valves are suitable for media flow control and isolation.
3. Different Operating Methods: Both diaphragm valves and globe valves can be operated manually, pneumatically, or electrically.
4. Different Safety Performance: Due to their poor stem sealing performance, diaphragm valves are prone to leakage, making operation and maintenance more difficult; while globe valves have good sealing performance, making operation and maintenance relatively simple.
GNEE Diaphragm Valves and Globe Valves factory
GNEE Group specializes in manufacturing globe valves and diaphragm valves. If you have any questions about selection, please contact us for the best choice for your project.