Problems with cavitation at the inlet of 2BV water ring vacuum pumps
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Check our operating procedures: first fill the pump, and it can be started once liquid begins to flow out from the cavitation valve. For cavitation prevention, our pipeline is directly connected to the gas-liquid separator. Ignore mirror. How can it be determined that there is liquid being discharged from the cavitation tube? (Feel it with your hand?)
There’s no need to get overly stuck on what’s written in the book; just raise the liquid level high enough, and that will ensure there’s liquid at the cavitation site
So, the only drawback of the pump designed by Siemens is that, when liquid is introduced in an open manner, it’s not possible to determine exactly how much liquid has entered. Usually, this is determined based on experience – 1 to 2 minutes after opening the inlet valve is sufficient… If automatic control is desired, a delay mechanism can be added
Can’t a hole be drilled in the protrusion on the right side of the pump cover to install a valve?
:L Why do you need to drill? If you want to add a valve, you can use a tee at the interface of the cavitation protection hole; moreover, by adding a check valve on the outside, you can achieve the desired functionality: excess water will overflow, and once it overflows, the system will start operating. When a certain level of vacuum is reached in the cavitation tube, suction occurs, and at that point the check valve will do its job……
Isn’t cavitation protection applied on the compression side? How can it continue to draw in air even when a certain level of vacuum is reached? If it is suction, what check valve can achieve very low leakage at kilopascal levels without affecting the pump’s vacuum? Question: D
It is correct to apply it on the compression side, but at the cavitation point of the 2BV pump designed by Siemens, when a certain level of vacuum exists, even if it enters the compression zone, the degree of compression still falls far short of what is needed to reach above atmospheric pressure; thus, a vacuum condition persists. There is no such thing as low leakage for check valves at the kPa level – the leakage amount of Siemens’ original check valves depends on the roughness of the valve body resulting from the combination of the valve body and the valve disc; in addition, the deformation of the valve disc under pressure is also a factor, but the overall leakage amount is determined by Poiseuille’s formula. Actually, the leakage rate is quite high... That’s why an additional manual valve is installed!
Thank you for the answer. I understand the cavitation protection part. I also understood the check valve, but what you should be referring to is the inlet check valve. What I would like to ask is, regarding the check valve for cavitation protection that you mentioned, is it a swing-type check valve?
This post was last edited by symc on 2022-4-21 at 11:38. A simple rotary type will suffice; it’s cost-effective. For better performance, one could redesign it using Siemens’ flange-type design… And for even better results, a duckbill valve with a float inside could be designed to allow water to flow out while preventing air from entering.