How does a negative-pressure container control the liquid level?
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This post was last edited by dwjgwsm on 2017-6-23 at 13:12. It involves a vertical vacuum tank with a pressure range of 0.03–0.05 Mpa and a volume of around 100 L; the liquid inside is non-corrosive (with a viscosity slightly higher than that of water), and it’s necessary to control the level of liquid flowing into the tank. Are there any simple and effective methods for this? I’ve thought of two approaches: one is to use a float valve installed on the flange at the top of the container, but I’m not sure whether such a valve works well in a vacuum system or if it might break easily. The second approach is to install flow meters on the pipes before and after the vacuum tank, and control the flow by comparing the readings from these flow meters. However, the disadvantages are as follows: 1. This makes the control system more complex; 2. Some people have suggested that due to errors in the flow meters, the actual control effect may not be good. I’m unsure now and would like to ask for everyone’s advice. Thank you!
Controlling the liquid level has nothing to do with pressure; the container is installed at a high position, and control is achieved through an overflow pipe.
The float valve that is purchased should have normal pressure inside, while the outside is at vacuum pressure; there is thus a pressure difference. Could this cause the float valve to fail? If a small hole is made in the float valve, the pressures inside and outside will become equal. However, over time, the inside of the valve might fill up with liquid due to splashing droplets and other factors, preventing the float from functioning properly. That’s one issue. Another issue is whether the part of the float valve where it connects to the external control rod is prone to air leakage
The container is fixed – how can a weight sensor be used in that case? With the sensor you mentioned, the process is not much different from using a flow meter; it also outputs a signal which is then sent to the solenoid valve by the control system. In other words, an additional flow meter is needed. The system itself also requires a flow meter to be installed
The container is fixed – how can a weight sensor be used in that case? With the sensor you mentioned, the process is not much different from using a flow meter; it also outputs a signal which is then sent to the solenoid valve by the control system. In other words, an additional flow meter is needed. The system itself also requires a flow meter to be installed
The container is fixed, so how can a weight sensor be used? With the sensor you mentioned, the process is not much different from using a flow meter – it also outputs a signal, which is then transmitted by the control system to the solenoid valve. In other words, an additional flow meter is needed; the system itself also requires a flow meter to be installed
In fact, the principle of controlling liquid level in negative-pressure containers is the same as that in positive-pressure containers.
The container is fixed, so how can a weight sensor be used? With the sensor you mentioned, the process is not much different from using a flow meter – it also outputs signals