There are various options to choose from when selecting vacuum pumps for an application. Small Vacuum Pump is available in many different types that offer varying displacement capacities and vacuum levels.
The four main types of vacuum pumps used in laboratories for freeze drying, evaporation, and concentration are as follows:
The traditional rotary vane small vacuum pump is widely used due to its low initial cost, wide range of applications, and small size.
One downside of RV pumps is that the oil needs to be regularly changed and is costly. The approximate use of the oil can be made for around 3000 hours.
The life of the pump is dependent on the maintenance of the oil. Even though automatic oil changing systems are available, it is still time-consuming.
These vacuum pumps reach deep vacuum levels and provide high displacement capacity. This makes them an optimum choice for freeze-drying applications.
Diaphragm Vacuum Pumps
These are dry pumps that make use of pulsing motion to operate. It opens and closes valves to move air. This design negates the need for oil.
The valves are made of polytetrafluoroethylene to make the pump corrosion-resistant and less susceptible to vapor damage.
Though they have a higher up-front cost, but the maintenance cost is significantly reduced because of the lack of oil.
These pumps have low displacement capacities and low ultimate vacuum pressure levels.
Diaphragm pumps are chemical- and corrosion-resistant, making them a good choice for evaporation and concentration.
A diaphragm pump is not suitable to be used for freeze drying because of low vacuum depth.
Combination Vacuum Pumps
These are also known as Hybrid Vacuum Pumps because they combine Rotary Vane and Diaphragm pumps.
So, while the up-front cost may be higher compared to an RV pump, the operation costs are considerably low as less amount of replacement oil is needed and also less time is lost changing the oil.
Combination pumps’ vacuum levels and displacement capacities are similar to those of RV pumps.
Because the diaphragm pump is also incorporated into the design, these pumps handle acids and solvents better than RV pumps.
Scroll Vacuum Pumps
They are dry pumps that make use of two spiral scrolls to compress air and vapors and move them towards the exhaust.
Though the up-front costs are higher, the operation costs are much less because they don’t require oil and are very low maintenance.
It is advised to change the scrolls after every 40,000 hours of use. Eliminating the oil and the hydrocarbon-free design means the pumps are environmentally friendly as well.
Scroll pumps also make significantly less noise during operation.
No matter what type of small vacuum pump you are using, one of the vital things to remember about them is that whatever goes inside the pump will come out!
It would be best to take precautions even with filters, especially when samples include potentially hazardous materials.