What are the precautions for starting up a water ring vacuum pump and for its maintenance, including anti-freezing measures?

The water ring vacuum pump (abbreviated as water ring pump) is a type of rough vacuum pump; the ultimate vacuum it can achieve is 2000–4000 Pa, and with an atmospheric ejector in series, this value can reach 270–670 Pa. Water ring pumps can also be used as compressors, known as water ring compressors; they are low-pressure compressors with a pressure range of 1~2×105 Pa gauge pressure. Advantages of water ring pumps: simple structure, low requirements for manufacturing precision, and easy to process. 　　It has a compact structure, with a high rotation speed; it can generally be connected directly to the motor without the need for a reduction gear. Therefore, a small structural size can yield a large displacement, while also requiring less floor space. 　　Compressed gas is essentially isothermal, meaning that the temperature changes very little during the compression process. 　　Since there are no metal friction surfaces inside the pump chamber, there is no need for lubrication within the pump, and wear is minimal. The sealing between the rotating part and the fixed part can be achieved directly by a water seal. 　　It features even air intake, stable and reliable operation, simple handling, and easy maintenance. Water ring pumps also have their drawbacks: their efficiency is low, generally around 30%, with better models achieving up to 50%. 　　The low vacuum level is due not only to structural constraints but, more importantly, to the saturated vapor pressure of the working fluid. Using water as the working fluid, the ultimate pressure can only reach 2000~4000 Pa. Using oil as the working fluid, a pressure of 130 Pa can be achieved. 　　In short, since the gas compression in a water ring pump is isothermal, it is possible to pump out flammable and explosive gases. Due to the absence of exhaust valves and friction surfaces, it is possible to extract gas containing dust, condensable gases, and gas-water mixtures. Thanks to these prominent features, it is still widely used despite its low efficiency. Common Faults 　　　I. Insufficient vacuum pump performance 　Possible cause: Inadequate power supply to the motor, resulting in insufficient rotation speed ； Insufficient water supply ； The gap between the impeller and the distribution plate is too large ； Damage to the mechanical seal causes leakage of fluid and air ； The impeller is excessively worn ； The circulating water cannot be drained. 　　Exclusion method: Check whether the supply voltage is within the motor’s rated voltage range ； Increase the water supply volume (it must be kept within the correct range; otherwise, the motor will overheat due to overload) ； Reduce the gap between the impeller and the distribution plate (usually 0.15–0.20 mm) ； Replace the mechanical seal ； Replace the impeller ； Check the pipeline at the outlet. 　　II. Failure to start or loud noise when starting Possible cause: Insufficient voltage supply to the motor ； Motor operating with a missing phase ； The pump has rusted due to long-term disuse ； Foreign objects drawn into the pump ； Impeller drag distribution plate. 　　Exclusion method: Check whether the supply voltage is too low ； Check that all motor connections are secure ； If the pump has rusted due to long-term disuse, some rust remover can be added, or the pump cover can be opened to manually remove the rust ； Open the pump cover to remove debris ； Adjust the distance between the impeller and the distribution plate. 　　III. Motor overheating Possible cause: Excessive water supply leading to motor overload ； Motor phase loss ； Exhaust vent blocked ； The impeller drives other components. 　　Exclusion method: Reduce the water supply volume to the normal range (refer to the flow rate specified in the pump’s instruction manual) ； Check whether the wiring is secure ； Check the exhaust outlet ； Open the pump cover to adjust the clearance between the impeller and other components. I hope the information above will be helpful to you.

Attention should be paid to the water inflow volume of the water ring pump; it should neither be too large nor too small. Be vigilant about the current at all times!

We use water ring vacuum pumps on the paper machine. The overall effect is still quite good. It would be great if it could have the efficiency of a turbine

Our company uses water ring vacuum pumps, and it is essential to ensure that there is no back pressure at the outlet of the vacuum pump when starting or stopping it. To protect the mechanical seal, turn on the water at the end face first

1. In winter, if the vacuum pump is not in use, the working water should be drained； 2. The working fluid level should be at 50-60% ； 3. Before starting the vacuum pump, drain the wastewater from the buffer tank ； 4. After starting, check whether there are any abnormalities in the motor current and sound ； 5. The working water pressure must be adjusted to meet the requirements.

Key operating points for water ring vacuum pumps: 1. Continuous water supply is required before the pump starts and during its operation； 2. The water supply flow rate is specified according to the pump’s instructions ； 3. During operation, pay attention to the water temperature according to the required vacuum level ； 4. When pumping corrosive gases, pay attention to the operating conditions of the scrubber tower before the vacuum pump and keep them within the normal range. 5. For vacuum pumps equipped with their own circulating cooling systems, it is important to properly control the concentration and temperature of the water in the circulating water tank, and to replenish water promptly.

This article is really good; thank you for sharing. Is a liquid ring pump a type of compressor?