Do you know how to choose the laboratory vacuum pump?
Vacuum pump is a function of removing gas molecules from the vacuum chamber and reducing the pressure of the gas in the vacuum chamber to the required vacuum degree.
The application of vacuum pump in laboratory is more and more extensive. Vacuum pump can be used with other instruments, not a single equipment. Vacuum pump is an indispensable auxiliary equipment in every laboratory. The application of different instruments and equipment has different requirements for vacuum pump. The following LAN fan to introduce the laboratory commonly used vacuum pump types.
Laboratory vacuum pump can be generally divided into two types: dry and non – dry
Dry vacuum pump:
Dry vacuum pump, also known as oil-free vacuum pump, is to rely on the machine’s own components to achieve the required vacuum degree, no pollution, no maintenance. The commonly used type in laboratories is the oil-free piston type (mostly used in microbiology laboratories) and the corrosion-resistant diaphragm type (mostly used in chemical laboratories).
Non-dry vacuum pump:
Non-dry vacuum pump, generally can be divided into oil vacuum pump, water cycle vacuum pump. The common point of non-dry vacuum pump is that it needs to achieve the ideal vacuum degree with the help of water and oil and other substances. The commonly used pump in the laboratory is the oil-type rotary vane pump, which is generally used in conjunction with the freeze-drying machine and vacuum drying box.
Choice of laboratory vacuum pump:
How to choose vacuum pump for laboratory? First of all, we should understand the purpose of vacuum pump and whether the gas extracted is corrosive. Generally, oil-free vacuum pump can be selected for filtering samples. Consider from vacuum pump configuration on other instrument equipment. If it is used to configure rotary evaporator, it needs to use the vacuum pump that is resistant to corrosion. If it is used for drying box, you can choose high vacuum such as non-dry vacuum pump in the pump.
Vacuum calculation
Most vacuum degrees in the laboratory are concentrated above 2mbar. In the low vacuum field, the extraction time follows the following relationship
T = V/Se x 1.303 log10 (P1 / P2)
In the formula:
P1 — initial pressure (atmosphere) [Pa]
P2 — reaches the pressure [Pa]
T — extraction time [min]
V – volume [L]
Se — actual pumping speed [L/min]
Considering the effect of pipeline and valve, the actual pumping speed is 80% of the theoretical pumping speed
Vacuum pump, divided into three series:
1, oil-free plunger pump, clean and efficient vacuum pump ideal choice, unique piston chamber design to ensure a long time of operation. Oil-free plunger pump is often used for laboratory vacuum filtration, vacuum drying box, etc.
2. Corrosion-resistant diaphragm pump. The whole gas path does not contact with the metal part of the pump body, and PTFE film covers the metal part. Diaphragm pump can be used with corrosive gas vacuum, such as: rotary evaporator, reaction kettle, etc
3, rotary vane pump is the use of oil seal for vacuum operation. Compared with plunger pump and diaphragm vacuum pump, rotary vane vacuum pump has higher vacuum degree, suitable for equipment with higher vacuum requirements, such as vacuum drying.
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