Can a liquid ring vacuum pump achieve a stable vacuum of over -99 kPa?

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We all know that the liquid ring vacuum pump is a type of vacuum generation method that operates by changing its volume. The ultimate vacuum level it can achieve is closely related to the type and temperature of the working fluid; in other words, it is the saturated vapor pressure of the working fluid at its operating temperature that determines the ultimate vacuum level that can be obtained by the liquid ring vacuum pump. For example, the saturated vapor pressure of water at 15°C is 1.7 kPa; therefore, a water ring vacuum pump operating at 15°C can achieve a vacuum level of up to 1.7 kPa (i.e., -99.6 kPa). So the question is: if a working fluid with a very low saturated vapor pressure at the operating temperature is used, can a vacuum pump achieve a higher vacuum level? For example, transformer oil or certain esters with high boiling points generally have a vapor pressure of only 0.1 kPa at 50°C; is it then possible to achieve such a high level of vacuum? I asked the Foshan water pump factory, and they said it’s impossible. It seems that there is a pressure difference ratio between the exhaust side and the suction side of the vacuum pump, and this ratio determines that no matter what working fluid is used, it’s not possible to achieve a stable vacuum of less than -99 kPa Does anyone have any experience using this in such contexts? If that’s the case, then what is the principle?