In the process of freeze-drying, vacuum control is very important.
In my opinion, whether the vacuum control is stable and accurate is one of the most important indicators to distinguish whether the lyophilizer is “good”. Temperature control is obviously much easier than vacuum control.
Many users who come to discuss with me the problems they encounter in the freeze-drying process also have a headache due to the accidental out of control vacuum. Is it a device problem? Or process problems? This is also a big story.
Because we all know that vacuum control is very important in freeze-drying process. So many users who have just contacted freeze-drying will be very interested in the vacuum pump equipped with the freeze-drying machine.
But in the actual freeze-drying process, the largest vacuum pump is the cold well of the freeze-drying machine. The cold trap will deal with all the pressure rise caused by the sublimation of water vapor.
The vacuum pump is responsible for the extraction of: upstream vacuum control air leakage, cavity leakage, gas in the product, these three parts, non condensable gas.
Because there are many users who are interested in and have questions about the vacuum pump, the next content will make a brief introduction to the mechanical component of the vacuum pump.
Vacuum level
Various types of vacuum pumps
Marked in green is the pump that will be used in the freeze-drying process.
It should be noted that the “cold trap” (usually liquid nitrogen cold trap) and condenser cold trap in the rightmost column. It’s also classified in the pump.
Different vacuum pumps have different working ranges
Chinese style lyophilizer, the most we use is the rotary vane pump
The vane pump is commonly known as the oil pump, where the oil plays the role of sealing and lubrication.
If the solvent is not completely captured by the cold trap, entering the pump, or the oil is used for a long time under high temperature, the quality of the oil will decline.
If the quality of the oil drops and the sealing cannot be completed well, the vacuum degree will not reach a very low value. If the quality of the oil drops, it can not be well lubricated, and the friction between the stator and rotor increases, permanent mechanical damage will be caused.
Therefore, regular inspection and replacement of vacuum pump oil is one of the important contents of freeze dryer maintenance.
In addition, there will be pre-stage pump and dry pump, as well as water ring pump in industrial freeze-drying.
The author of this paper is not very familiar with the mechanical components of the industrial lyophilizer, so he will not teach others how to do things here.
If possible, kindly suggest please your working industry/process, working pressure, working medium, etc. Given detailed request helps to gain better-matched customized solution. Thanks for your patience.
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