What does the ultimate vacuum of a liquid ring vacuum pump refer to?
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The ultimate vacuum achievable by a liquid ring vacuum pump can reach 4000 Pa – does this refer to the inlet pressure? Why is there an ultimate vacuum limit? If the pump’s speed is increased to boost flow rate and thus more gas is pumped out, will there also be a limit to the vacuum level in the upstream container? Why is that? And why does the medium used in the liquid ring pump affect the ultimate vacuum level as well?
(1) Gas volume Q: The gas volume of a liquid ring vacuum pump refers to the volume of gas in suction condition that passes through the pump’s inlet per unit time, when the pump outlet is at atmospheric pressure (760 mm Hg) (in m3/min). Gas flow rate of a liquid ring compressor: It refers to the volume of gas that passes through the compressor inlet per unit time (in m3/min), when the inlet pressure is at atmospheric level (760 mm Hg). (2) Limit vacuum of the liquid ring vacuum pump: refers to the degree of vacuum when the gas flow rate of the liquid ring vacuum pump is zero. (3) Maximum discharge pressure of the liquid ring compressor: refers to the discharge pressure (gauge pressure) when the gas volume of the liquid ring compressor is zero. The performance of a liquid ring vacuum pump is related to the state of the gas being transported, as well as the properties and temperature of the working fluid; typically, only the characteristic curves under specified conditions are provided. When the actual conditions do not match the specified conditions, the pump’s performance should be adjusted or corrected
It is related to the saturated vapor pressure of the circulating liquid; different circulating liquids result in different ultimate vacuum levels. The higher the saturated steam pressure, the lower the ultimate vacuum. As the pumping volume increases and exceeds the system’s leakage rate, the vacuum level in the system gradually rises. When it reaches the saturated vapor pressure of the circulating liquid, the liquid vaporizes, and the cavitation pump can no longer operate properly.
Therefore, when a liquid ring pump is in operation, the temperature of the circulating liquid must be strictly controlled