The required minimum suction vacuum for a rotary compressor varies depending on the application; however, in engineering, compressors can achieve a substantial vacuum with figures such as 25.0 atm negative pressure being mentioned within context.
A rotary compressor should be capable of reaching a minimum suction vacuum relative to the specific system requirements, with exemplary cases achieving a vacuum as low as 25.0 atm negative pressure. This is of particular significance when it comes to systems requiring substantial pressure reduction as found within refrigeration cycles.
For example, a refrigerator with a coefficient of performance (COP) of 3.0 needs 200 J of work to extract a certain amount of heat per cycle, illustrating the importance of the compressor's capability to attain such vacuum pressures to facilitate the refrigeration process.
The capability to achieve specific vacuum pressures is dependent on the type of compressor in use and the specific engineering requirements, such as, providing the conditions necessary to raise water to a certain height under a negative gauge pressure, or realizing the best COP for a refrigerator aimed at making liquid nitrogen.
So, there isn't a one-size-fits-all answer to the minimum suction vacuum a rotary compressor should pull as it greatly depends on the specific application and operating conditions. However, in engineering contexts, it is not uncommon for sophisticated systems to aim for remarkably low pressures, sometimes achieving vacuums that bring significant mechanical consequences to the equipment involved.