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.” In our previous blog entry (Vacuum Pump Service, Part 1) we discussed the selection of the right pump technology. Today we’ll address how to protect your pump during use.
Keep out those liquids and particulates
Vacuum pumps are designed to move vapors or gases. If you are working with corrosive vapors, you need to protect the pump mechanism by choosing a pump with “wetted” surfaces (those directly in contact with the gases and vapors being pumped) that are resistant to these chemicals. This can be difficult with oil-sealed pumps; they achieve deeper vacuum largely by having very tight, metal-to-metal tolerances. The oil will become contaminated by vapors or gases being drawn through the pump, affecting its lubricating and sealing properties. Further, oil contaminated with corrosive materials becomes corrosive itself. The solution is to change the oil.
One pump technology that can help with such circumstances is the hybrid vacuum pump. A hybrid pump combines a rotary vane pump (to achieve fine vacuum levels) with a chemical-resistant diaphragm pump that keeps the pump oil under vacuum. The effect is to continuously distill corrosive contaminants out of the oil, extending service intervals by as much as ten times. These pumps are a bit more expensive than a conventional rotary vane pump, but quickly recover the price premium in avoided service costs.
If there are particulates or liquids in the gas or vapor stream, they need to be removed before they reach the pump. For rotary vane pumps, this means the use of a cold trap and inlet separator. For a diaphragm pump, a cold trap may not be needed (check with your manufacturer) but an inlet separator is a useful precaution. The inlet separator is usually a plastic or glass flask at the pump inlet that collects particulates or condensate before it reaches the pump.
Notice that protecting pump oil – which protects the pump – is very important. But if you don’t need vacuum of this depth, a diaphragm pump will not only be the right technology for your application but offer significant service advantages. And diaphragm pumps are available with chemical-resistant wetted paths that offer exceptional protection against corrosive reagent vapors.
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.