The issue of rapid leakage of the electric butterfly valve DN350 when used in air pipelines at 50°C
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This post was last edited by WQC on 2010-10-16 at 17:01. Three DN350 electric butterfly valves were installed on the ventilation pipes of the aeration tank in our company’s wastewater treatment plant. Air is supplied by a Roots blower, with a temperature of around 50°C. Leakage occurred after just one month of use; the supplier said that adding water to the pipes to lubricate the seals would be necessary in order to extend their service life. Later, he recommended a Sino-foreign joint venture manufacturer in Xiamen that offers products at a higher price, and the results so far are good. Can butterfly valves be used to handle air with a certain degree of temperature?
Thank you, it’s not a hard seal; it has a rubber seal
This has nothing to do with the type of butterfly valve, nor is it related to temperature. Because when you provide the parameters to the manufacturer, they already take into account whether it can function in air at 50 degrees Celsius when selecting the appropriate model. You say the butterfly valve is leaking; I think there are two reasons for this: 1. When selecting the valve, the vacuum level of the Roots blower wasn’t taken into account, which resulted in an excessive pressure difference before and after the valve, thereby damaging the rubber seal – in other words, the rubber seal cannot withstand such a high pressure difference ； 2. The medium flowing through is not pure; when the butterfly valve is closed, impurities wear out the rubber seals, resulting in leaks. Recommendation: Use a hard-sealed version; of course, you need to inform the manufacturer about the desired leakage level. A friend was also right; if the butterfly valve is installed in the wrong direction, it can also damage its functionality.
I can only say that the valve products used by your company are not up to standard; the valves in this application are just ordinary control valves. It would be better to use higher-quality ones, as that would save time and effort
Butterfly valves are not suitable for use in pipelines that transport gases. Even if butterfly valves are to be used, it is necessary to contact the manufacturer to select the appropriate model. Generally, hard-sealed butterfly valves are chosen; for rubber-sealed versions, center-line butterfly valves with stainless steel valve discs and fully lined with rubber are used. We use hard-sealed butterfly valves here, while in some cases rubber-lined butterfly valves are used, with valve discs made of 304 material. Furthermore, it is important to choose a manufacturer of high quality – don’t hesitate to invest more money in this regard.
If a triple-eccentric metal hard-sealed butterfly valve is used, it can also be used at temperatures of 1000 degrees Celsius. Your factory has chosen ordinary soft-sealed butterfly valves with a center line design; the sealing is achieved by the compression of rubber between the valve disc and the valve seat, causing the rubber to deform. If the rubber ages or if impurities in the gas scratch the sealing surface, internal leakage will inevitably occur. Additionally, the pressure difference must be taken into account, as medium-line soft-sealed butterfly valves cannot withstand pressure. If long-term stable operation without leakage is desired, it is recommended to use a double-eccentric hard-sealed butterfly valve for this purpose, as it offers a good cost-performance ratio.
Reply 1# wlhmsh: Domestic products have a slightly higher temperature, which makes it easy to encounter missing data; our customers who used domestic products reported this issue all the time, so they switched to imported ones.
For a centerline butterfly valve like yours, it’s better to choose a reputable domestic brand. The manufacturer is right; adding some sealing measures will allow it to last longer. 50°C – what kind of temperature is that! There is absolutely no need to use double eccentric or triple eccentric designs.
It’s probably a problem with the sealing material – some types of rubber are not suitable for use in environments with air, or the sealing materials chosen by the valve manufacturers are of poor quality, which leads to internal leaks! QQ: 928976489 (Control Valve Consultant)
Your temperature and medium are quite ordinary; the leakage in the valve is likely due to a sealing issue. This seal is installed after the valve is assembled, and it isn’t fixed to either end of the valve body, which causes the seal to shift during operation and results in leakage. It is recommended to use valves from manufacturers with a good reputation and positive customer reviews. If that’s not possible, consider using imported valves – they aren’t much more expensive than domestic ones. The important thing is to solve the problem, as the benefits resulting from the continuous operation of the factory far exceed the cost of a few valves. I have used many valves on rotary vacuum pumps. If you still can’t resolve the issue, we can discuss it further; I hope I can help you. QQ: 120519927
It’s still a problem with the quality of the valves; there are too many valve manufacturers in China. The quality varies. Your operating conditions are quite ordinary. Personal suggestion: A regular medium-line soft-sealed butterfly valve will suffice. Consider using a vulcanized rubber valve seat. In this way, it won’t contract even with a vacuum valve seat.