Points must be paid attention to when using vacuum pumps

Between the distillation system and the vacuum pump, an absorption device must be installed.
The vapor of the organic solvent in the system must be thoroughly pumped out with a water pump before distillation.
If you can pump gas with a water pump, try to use a water pump, if the distillate contains volatile substances, you can first use the pump to reduce the pressure and pump, and then switch to the oil pump.
The decompression system must be kept airtight, the size and orifice of all rubber plugs should be suitable, and the rubber tube should be used for vacuum. The ground glass is coated with vacuum grease.
According to the scope of use and pumping efficiency, vacuum pumps can be divided into three categories:
(1) General water pump, the pressure can reach 1.333~100kPa (10~760mmHg) for "coarse" vacuum.
(2) Oil pump, the pressure can reach 0.133~133.3Pa (0.001~1mmHg) for "sub-high" vacuum.
(3) Diffusion pump, pressure can reach 0.133Pa or less, (10-3mmHg) for "high" vacuum.
If you want a lower pressure, you need to use an oil pump, a good oil pump can pump below 133.3Pa (1mmHg).