How To Choose A Laboratory Vacuum Pump


How To Choose A Laboratory Vacuum Pump

A laboratory vacuum pump is a versatile tool that can help a wide diversity of research engineers and scientists. These are used in labs on a routine basis:

  • To offer suction to drive the filtration of suspended samples or fluids.
  • To control solvent evaporation by minimizing vapor pressure.
  • To boost instrument-detection sensitivity by assessing air molecules that contaminate samples in a mass spectrometer.
  • To gather gas samples from the test chambers.
  • To enable a negative pressure environment to avoid losing out potentially hazardous sample materials.

When it comes to choosing a vacuum pump, there are many options in different types that provide various displacement capacities and eventual vacuum levels.

There are four main types commonly used in laboratories for freeze-drying, concentration, and evaporation.

Rotary Vane

These are smaller than other types and can have a lower up-front cost, used with multiple applications. These use oil to assure a tight seal, smooth movement of working parts, and eliminate the heat to cool the rotors.

It’s important when using an RV pump to gather the evaporated vapors and protect the pump. The oil in these pumps must be checked routinely and changed after every 3,000 hours of use.

The life expectancy depends on the maintenance of the oil. These pumps reach deep vacuum levels and offer high displacement capacity, which makes them an ideal choice for freeze-drying applications. They work very well for aqueous solvents with high boiling points that the vapors can be trapped easily before they reach the pump.

Diaphragm Pump

The Diaphragm is dry pump that work using a pulsing motion, which opens and closes valves for air movement. While they could have a higher up-front cost, they don’t use any oil, so maintenance costs are relatively lower than other pumps. They can be used with a wide range of samples, but have limited applications to those needing higher final vacuum levels.

Ultimate vacuum levels are not excessively deep, and displacement capacities are lower than other vacuum pumps. These are one of the most chemical- and corrosion-resistant pumps. Thus, almost any kind of sample, even those having a combination of solvents, can be used with this laboratory vacuum pump, making them an ideal choice for both concentration and evaporation.

Scroll

These are dry pumps, which operate two spiral scrolls to compress vapors and air and move them toward the exhaust. The lifetime work costs are much lower as they don’t need oil, and little maintenance is required.

It is recommended to change the scrolls every 40,000 hours of use. The hydrocarbon-free design signifies that these pumps are environmentally friendly too. These pumps manage water vapor better than other types of pumps and produce relatively less noise while operation. Scroll pumps can reach deeper vacuum levels and contain higher displacement capacities.

They can be used with solvent samples like Acetonitrile. They might be used with concentration applications too.

Hybrid

These have both a Diaphragm pump and rotary vane together in the same vacuum pump. In a hybrid pump, the diaphragm keeps the oil of the RV under negative pressure to eliminate or reduce vapors going through it. This design allows for less frequent changing – oil stays up to 10 times longer in between changes compared to RV pumps.

While there might be a higher up-front cost than the RV pump, the operation costs are lower as less replacement oil is required. The displacement capacity and final vacuum levels with hybrid are similar to those of RV pumps. Since the diaphragm pump is included in the design, these pumps are better at solvents than RV pumps.

These pumps are used for freeze-drying volatile samples, with acidic samples and those having harsh chemicals like Acetonitrile, TFA, and Nitric acid.

Conclusion

Regardless of what type of pump you use, one important thing to remember is that whatever goes in the pump will come out! Also, with filters, you need to take precautions when samples contain potentially hazardous materials.

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