Lab vacuum pumps are exposed to all kinds of challenging substances: acid vapors, organic solvent vapors, water, particulates. It’s not surprising that a product designed to create suction would have to contend with all of these materials, but does it have to be such a headache?
The answer is “No,” and you can greatly reduce the challenges of vacuum pump maintenance by selecting the right pump technology for the application, protecting your pump, and servicing the pumps on the manufacturer’s recommended schedule. In this blog entry, we’ll address selecting the right pump technology.
Selecting the right pump technology
Vacuum that is used in labs covers a huge range of performance – literally many orders of magnitude. Consider that, on one absolute scale for measuring vacuum (i.e., zero equals perfect vacuum), atmospheric pressure is at about 1000 mbar. Filtration and aspiration tasks can typically accomplished at a few hundred mbar of vacuum. Water can be brought to boil at room temperature at about 23 mbar. Freeze dryers and Schlenk lines need 10-3 mbar, and instrumentation like mass spectrometers, which may need vacuum at 10-12 mbar! No pump can satisfy all of these conditions effectively, so an important rule is, “Deeper vacuum isn’t always better.” In fact, it may be a problem. What’s important is to use a pump that delivers vacuum appropriate to the operation for which you need the vacuum pump.
As an example, rotary vane pumps (direct drive or belt drive) are common in labs, and are usually designed to produce vacuum at about 10-3 mbar. That’s ideal for molecular distillation or freeze drying, but 5 orders of magnitude deeper than needed for filtration, and 4 orders of magnitude deeper than needed for most evaporative tasks in the lab. Efforts to force rotary vane pumps to operate at “rough vacuum” levels result in noise, oil mist, excessive service needs and risk of sample loss. For these applications, diaphragm pumps are the right choice; they are designed to provide the vacuum for routine aspiration, filtration and lab evaporation and drying tasks.
Talk with your vacuum pump manufacturer if you are uncertain about what pump technology is the best fit for your needs. And watch for upcoming entries to address protecting your pump and suggested service intervals.
If you need help selecting a vacuum pump for your lab or scale-up facility, try our Vacuum Pump Selection Guide, and get a recommendation after answering fewer than 5 questions. If you are building or renovating labs, and need to serve numerous users, consider opting for a local vacuum network over a house system. To learn more, or get help specifying a network, contact us today.