Vacuum pumps are used in a wide variety of industries and applications. In both laboratories and production facilities you’ll find vacuum pumps on a range of machinery from vacuum ovens, rotary evaporators, distillation systems, to filtration systems. Vacuum pumps are the engine that help get the job done. Oven Cascade Sciences carries a wide variety of vacuum pumps for many different applications including bioscience, aerospace and pharmaceutical industry requirements. Learn about the different kinds of vacuum pumps on the market and how to go about selecting the right pump for your process.

How to Select the Right Vacuum Pump For Your Process

The wrong pump can make vacuum drying inefficient, expensive and can even run the risk of contaminating your product, therefore, choosing the right pump for your process is important. We carry rotary vane pumps, oil-free dry scroll pumps, and diaphragm pumps, all of which have different features that make them a good fit for different types of applications.
  • Rotary Vane vacuum pumps are ideal for industrial non-cleanroom environments, where high CFM and deeper vacuum are required. They tend to be economical, smaller than other pumps, and can be used with multiple applications. One downside is that the exhaust ports on oil rotary vane pumps typically must be filtered using traps to prevent oil from backstreaming up inside the oven and contaminating your product. Rotary vane pumps also require regular oil changes in order to maintain the life of the vacuum pump.
  • Oil-Free Dry Scroll pumps – because they’re oil free – are very popular in clean rooms or environments where you need to eliminate the risk of contamination. Compared to diaphragm pumps, dry scroll pumps can reach deeper ultimate vacuum levels and they require no oil and very little maintenance, which means the lifetime operation cost is lower. In addition, scroll pumps tend to be very quiet so if you need a quieter pump, scroll pumps are a great fit.
  • Diaphragm pumps are also oil free and have been a laboratory and R&D staple for years because their PTFE interiors can handle pumping pharmaceutical solvents and more aggressive compounds. While these pumps have a higher up-front cost they do not require oil so operation and maintenance costs are significantly lower than for rotary vane pumps.
Check out Cascade’s application-specific pump selection:

Understanding Vacuum Pump Performance Criteria

To help select the right vacuum pump for your application begin by identifying a basic set of conditions that the pump is expected to meet: What level of vacuum needs to be achieved? The level of vacuum is expressed in a measurement of pressure, sometimes called base pressure, end pressure or ultimate vacuum. These measurement units include torr, millibar, pascals, or inches of mercury (“Hg). Vacuum pumps do not typically have a vacuum gauge built in. The vacuum reference gauge tends to be installed inside the vacuum oven or with a gauge in-line on the vacuum lines. However, when manufacturers state a vacuum pump’s ultimate pressure, they state it in optimal conditions at the pump’s inlet. Ultimate pressure levels can be impacted by the amount of off-gassing or gas load the vacuum pump must contend with. We list the ultimate pressure for each vacuum pump we sell in the Specifications sidebar to make it easy for you to select the right pump. What are you pumping? During vacuum bake-out or drying, there can be a variety of materials outgassing off your product. These can be a simple and harmless combination of water, air, nitrogen, argon, and/or helium. However, it’s critical to identify whether or not there will be a mix of gasses which include corrosive, flammable, explosive, or condensable gasses such as water vapor, or other vapors which can condense into liquid. If you are pumping corrosive, flammable or explosive gasses you will need a hermetically sealed pump (see below). Are you pumping corrosive, flammable or explosive gasses? This mix can require vacuum pumps that are hermetically sealed from inlet to outlet, or for corrosive ingestions the Edwards nXDSiC Scroll pumps with Kalrez seals, or the rugged Welch 1400. Diaphragm pumps with PTFE seals and diaphragms are also popular to resist solvents. Some vacuum pumps even have explosion proof motors. A hermetically sealed pump, sealed form inlet to outlet can bring the potentially flammable or explosive gassing to where, once exhausted from the pump, they can be diluted to a less-than flammable percentage. If you are pumping pure oxygen, an oil-sealed pump must use a pump oil that is not hydrocarbon-based, as the oil vapor mixed with the oxygen could cause an explosion. A dry compression pump is a logical alternative. Are you pumping condensable vapors? If you pump condensable vapors such as water vapor, or your process is removing substances which can clog the pump, consider an oil-free pump. Oil pumps can be easily contaminated and have their performance compromised by contamination and clogging.

Volume. Bigger Not Always Better.

The simple rule is, the bigger the volume, the longer it takes to reach the pressure you want to reach. The only way to shorten the time is to increase the pumping speed of the pump. Pumping speed is expressed in terms such as cubic feet per minute (CFM), or cubic meters per hour (m3/hour), or liters per second (L/S), or many other terms for volume per unit of time. We list the CFM for all the pumps we sell in the title of the pump to make it easy for you to see how fast they pump. Keep in mind that a bigger pump does not necessarily mean that you can shorten your process. For example, on a 5 cubic foot vacuum oven, a vacuum pump with a pumping speed of 5 CFM (cubic ft per min) is an appropriate match. However a 5 cubic oven paired with a 1 CFM (cubic feet per min) pump may likely underperform or not have the power necessary to create a solid seal on the components it’s pumping against. If you are removing gas from a substance, you can only pump as fast as the gas can be removed. Find the correct size pump for each application is the key; just buying a bigger pump could result in having a poorer result than the right-sized pump. Specific applications, such as short path distillation vacuum pumps may also require specific flow rates across the condensable surfaces.

Vacuum Pump Accessories

Protect your vacuum pump investment with our full range of vacuum pump accessories. Keep your vacuum pump performing optimally with rebuild kits, oil, and tip seals for all makes and models.

Have questions? Call 503-847-9047  for vacuum drying expertise.

Contact us for expert direction on selecting your vacuum oven packages by dialing extension #1.