I have a few questions about valves

This post was last edited by ylb913 on 2015-12-3 at 18:22. 1. When the ball valve is fully open or fully closed, the sealing surface of the valve seat does not come into contact with the medium； 2. The regulation of flow distribution by the butterfly valve within an opening range of 0–60% is approximately linear ； 3. Needle valves belong to globe valves ； 4. Kauk is a plug valve; it is the transliteration of the Soviet term for “switch”. It is used in similar situations to ball valves, but its sealing performance is slightly inferior to that of ball valves.

Thank you for the reply. I have 2 more questions. First, is a detached valve core the same as a detached valve stem? In the case of a control valve, I understand that the valve can still function even if its core is detached. And if the valve stem comes loose, it can no longer function. 2: Which outlet will be blocked if the spool of the three-way valve comes loose? I’m a beginner

Solid skills indeed:handshake

The separation of the valve core and the separation of the valve stem are different, just as in the case of control valves

Ball valves come in many structures. For O-type ball valves with double seats, which are used for coking media, purging is required. If the medium contains a high amount of particles, the sealed valve chamber can easily get blocked, preventing the valve from opening; in such cases, it is necessary to design them with single seats. The high viscosity is not a big problem. Butterfly valves exhibit a throttling effect at low opening angles; when the opening angle exceeds 30 degrees, their behavior is similar to that of quick-opening valves, with little impact on flow rate. This is related to the valve diameter and the structural design of the butterfly valve. The larger the valve port diameter, the more pronounced the adjustment characteristic between 15-45 degrees. Specially designed disc plates can achieve near-linear behavior. Over 90% of needle valves have a globe valve structure; in a narrow sense, a needle valve refers to a globe valve with a throttle needle-shaped valve disc. In a broad sense, needle valves refer to low-diameter instrument valves, which sometimes appear in the form of plug valves or ball valves. A quark refers to a plug valve; plug valves are classified into hard-sealed, ferrule-type, and oil-lubricated types. Nowadays, they are sometimes also considered as track plug valves. One advantage of the plug valve is that it does not have a sealed valve chamber, and it performs well in certain applications. Hard-sealed valves are commonly used with crystalline media such as soda ash, but they have poor sealing performance. Cartridge seals offer good sealing performance and are widely used in industries such as asphalt, acetic acid, and urea. Oil-lubricated seals are generally used in natural gas branch pipelines and media like slurry. Clamped types are widely used in the petrochemical industry, most notably in the oil transfer pipelines of oil depots. In control valves, it is more common for the valve disc to come loose, while the valve stem coming loose is less frequent. Generally, the detachment of the valve disc is caused by vibrations that lead to the breakage of the valve stem, resulting in a separation at the connection point between the valve flap and the valve disc. In such cases, if the pressure difference is high, the valve can still function temporarily; this applies to cage-type control valves, but not to those with a single seat, as in those cases the valve flap will move around. The valve stem usually comes loose at the point where it connects to the actuator; once this happens, the valve ceases to function. Three-way valves come in two types: union valves and diverter valves, and the ports that get blocked when the valve discs fall off are different. It generally depends on the installation location, so it can’t be generalized.