Commonly used solvents are methanol, acetone, ethanol and other organic solvents or other composite solvents. Their common characteristics are low boiling point and high saturated vapor pressure.
For the drying chain, there are usually two kinds of vacuum pumps, that is, before the pump and after the pump condensing, also known as the inlet side of the condensation and exhaust side condensation, all need to make the cooling medium boiling point is lower than the corresponding pressure.
Steam pressure curve of several common organic solvents.
From the extreme pressure range (0.1 ~ 100 Pa) drying process curve, it can be seen that the boiling point of the three solvents is between 90~30 degrees, and low temperature or cold trap condensation must be used.
Under the pressure (1.013 x 105 Pa), the boiling point of the three solvents is between 56~78 degrees, which is only related to the condensation of circulating water.
Comparatively speaking, the condition of condensing condensation at the exhaust side is the simplest and the most economical.