Material of the sealing surface for the butterfly valve used in dichloroethane exhaust gas absorption
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The company has over thirty butterfly valves of DN250 type for absorbing exhaust gases containing dichloroethane and dichloromethane; the sealing surface material is FKM. After being in use for about 8 months, aging of the sealing rings has occurred. The exhaust gas absorption process consists of three steps: adsorption, desorption, and cold cutting, with the absorption temperature being at room temperature ； Desorption steam, temperature at 100-110℃ ； Cold cutting uses an air compressor plus cold cutting water system, with the water temperature being close to room temperature. What material is suitable for the sealing surface in this operating condition?
Have you considered trying Teflon materials? I would recommend options such as PTFE, F46, or even the superior PFA for use as sealing rings in valves. Our company (which manufactures valves) now uses fluororubber very rarely as a material for sealing rings!
F46 tends to harden under sudden cooling and heating conditions; there are now several units made of F46 that experience the problem of not being able to be shut off
Have you considered trying valves with a pure hard-seal design, where the valve disc is clad with Stellite and the sealing ring is made of 316SS? Of course, the valve type should be a triple-eccentric butterfly valve.
Rigid seals cannot be used for exhaust gas absorption, as there is a risk of explosion. Now the valve is triple-eccentric, and it’s not easy to change the soft seal to a hard seal.
Although hard-sealed valves cannot achieve the same level of sealing performance as soft-sealed valves, they can still provide a VI-level seal. On the other hand, soft-sealed valves require frequent replacement of their sealing rings, which is not ideal. In this light, hard-sealed valves do not need to be shut down for replacement or maintenance, have a longer service life, and thus offer better cost-performance ratios!
Hard-sealed designs are concerned about the generation of sparks, although the probability of this occurring is extremely low. This requires hermeticity; there must be no air leakage between the first, second, and third absorption beds, and the three beds operate under different processes during operation. It’s quite difficult to achieve V-grade sealing for butterfly valves, right? Is VI a bit excessive?
This post was last edited by The boss is serving congee on 2019-6-13 at 15:45. Great, I’ve learned something! If new materials are found to replace the current ones in the future, remember to reply! (Additionally, as for the level of sealing performance that can be achieved with hard-sealed butterfly valves, this will improve over time as technology advances. You can take a look at our company’s samples. To clarify, I’m not a salesperson; I’m someone who specializes in valve selection, so I guess I can be considered semi-technical!) Haha~) Regarding your concern about contact, the three-eccentric butterfly valve design should help avoid this issue, as the valve disc and seat only come into contact when the valve is closed, thus preventing friction or wear!
In-depth discussion, learn*learn*: lol