The core difference between rising stem gate valve and concealed stem gate valve is mainly reflected in the structural design, operation mode and applicable scenarios, and the specific analysis is as follows:
1. Structural design and visibility
Valve stem visibility
The valve stem of the rising stem gate valve is exposed outside the valve body, and the lifting and lowering status of the valve stem can be observed visually when opening and closing; the valve stem of the concealed stem gate valve is completely hidden inside the valve body, and is only controlled by rotating the handwheel, and the opening cannot be directly judged.
Transmission mechanism
The rising stem gate valve drives the gate plate to rise and fall vertically through the threaded transmission of the valve stem and the handwheel, and the handwheel position is fixed;
The valve stem of the concealed stem gate valve rotates by itself, drives the gate plate to move through the internal thread, and the handwheel and the valve stem rotate synchronously.
2. Installation and maintenance characteristics
Space requirements
When the rising stem gate valve is opened, the valve stem rises, resulting in an increase in the overall height, and sufficient installation space (such as ground or overhead pipelines) needs to be reserved; the concealed stem gate valve has a compact structure and a fixed height, which is suitable for underground pipelines or narrow areas.
Maintenance convenience
The stem of the rising stem gate valve is exposed, which is convenient for lubrication and cleaning, but the thread is susceptible to environmental corrosion; the stem nut of the concealed stem gate valve is in direct contact with the medium, which is difficult to maintain and the thread is susceptible to medium erosion.
3. Performance and applicable scenarios Sealing and tolerance
The sealing surface of the rising stem gate valve is susceptible to medium erosion and requires regular maintenance; the concealed stem gate valve adopts a metal seal design, which has better sealing performance, but the stem is susceptible to corrosion due to long-term contact with the medium.
Typical application
The rising stem gate valve is suitable for small flow and low pressure scenarios (such as the outlet pipe of a fire pump), relying on manual operation and real-time monitoring;
The concealed stem gate valve is more suitable for large flow and high pressure systems (such as industrial pipe networks), and is often integrated into automated control processes.
Fault protection
When the concealed stem gate valve is out of air/power, it needs to rely on a reset spring, while the rising stem gate valve can quickly judge the fault status through the external stem position.
4. Operation feedback and safety
The rising stem gate valve provides intuitive opening feedback through the valve stem lifting and lowering, reducing the risk of misoperation; the concealed stem gate valve needs to rely on the opening indicator to assist in judgment.
The concealed stem gate valve has a stronger ability to resist external physical damage because the valve stem is built-in; the rising stem gate valve needs to pay attention to the dust and corrosion protection of the exposed valve stem.
Through the above differences, the engineering design needs to comprehensively consider factors such as fluid characteristics, space limitations and maintenance costs to select the appropriate type.
