Which High Vacuum Pump Is Right For My Application?

High Vacuum (HV) pumps offer many benefits to vacuum engineering applications. HV pumps use a pressurized system to remove gaseous substances or air out of a tank. The gaseous molecules are either discharged to another tank or into the ambient air. Here is how to select the right HV pump for your application.

Industries and Applications for HV Pumps

HV pumps are mainly used in semiconductor manufacturing. The types of industries and applications include:

• Analytical
• Coating
• Food Packaging
• Freeze Drying
• Heat Treatment
• Medical Metallurgy

HV Pumps

The types of HV pumps are:

• Cryopumps
• Diffusion pumps
• Ion/Sputter/Getter pumps
• Turbomolecular (TMPs)

Note that with exception of diffusion pumps, ultrahigh vacuum pumps are available in the HV types listed above.

The working range for HV pumps:

• 10-7 to 10-3 mbar

The working range for ultrahigh vacuums:

• 10-13 to 10-7 mbar

Diffusion Pumps to Support Fore Vacuums

A diffusion pump can operate together with a fore vacuum if you are using a high vacuum process. Matter of fact, a fore vacuum is necessary to work in conjunction with any HV pump at various stages. Some examples include supporting the pump’s operation, the first evacuation, and as an exhausted force. Note that your fore vacuum could be a scroll, diaphragm, screw, or oil-sealed rotary vane. Fore vacuum is commonly used in food packaging, freeze-drying, and heat treatments.

Diffusion pumps are excellent for industrial environments. The diffusion pump you select to work with the fore vacuum will increase the processing speed. Oil contamination is a possibility with diffusion pumps, so keep this in mind.

The diffusion pump’s working range pressure points:

• 10-7 to 10-3 mbar

Pumping speeds:

• 80 to 50,000 l/s

There is a notable cost for energy consumption and cooling water usage with diffusion pumps. This is expected because they are made to handle industrial processes in rough environments.

HV Turbomolecular Pumps (TMPs)

Although a turbomolecular pump (TMP) does not have the pumping speed of a diffusion pump, it is an oil-free option.

The TMP’s working range pressure points:

• 10-10 to 10-2 1/2 mbar

Pumping speeds:

• 30 to 4,000 I/s

TMPs are suitable for clean vacuum processes, and the cost to maintain TMPs is not as high as it is for diffusion pumps.

Cryopumps

A cryopump is a gas entrapment pump. Cryo’s are appropriate for processes requiring the pumping speed near to the range of a diffusion pump. There is no risk of oil contamination with a cryopump because it uses a low temperature to trap gases.

The cryopump’s working range pressure points:

• 10-11 to 10-4 mbar

Pumping speeds:

• 400 to 60,000 l/s

Cryopumps are oil-free. Overall, it may cost less to operate cryopumps compared to other options. Just like TMPs, cryopumps are suitable for clean processes. They are not recommended for heavy industrial environments.

HV Ion / Sputter / Getter Pumps

Ion pumps, also referred to as sputter pumps or getter pumps, are suitable for bulk gas removal. Ion pumps do not use valves or moving parts to generate ultra-high vacuum (UHV). They often operate in conjunction with a TMP to reduce the vacuum level to at least 10-4 mbar.

The HV ion’s working range pressure points:

• 10-11 to 10-4 mbar

Pumping speeds:

• 100 to 6,000 l/s

Pumping speed special range:

• 30 to 100 I/s

Because ion pumps do not use moving parts or valves like other HV pumps, the cost for maintaining the pump is lower. Ion pumps are efficient and quiet as well. Applications for ion pumps include molecular-beam epitaxy (MBE), surface analysis such as with tunnel microscopes, and physics including synchrotrons, colliders, and other high-energy applications.

Factors to Consider When Selecting an HV Pump

Dirtier environmental processes such as those that involve gaseous extraction require higher pumping speeds. Diffusion pumps and cryopumps have pumping speeds to between 50,000 and 60,000 I/s. This outpaces ions and TMPs. The cost of maintenance and initial investments are higher too.

Cleaner processes don’t require as high pumping speeds as dirtier processes. The maximum range for TMPs and ion pumps is between 4,000 and 6,000. Thus, the cost of maintenance and upfront investment will be lower.

The right HV pump for you largely depends on the vacuum level requirements for your type of application. Pumping speeds and operational costs are also important.

A high flow rate means that the machine will drain faster. HV pumps have between 1013 and 109 molecules per cm-3 remaining. Ultrahigh vacuums have between 109 and 104, and rough vacuum pumps have between 1016 and 1013 molecules per cm-3.

Gas compatibility is essential to look at too. Think about what could happen if the gases aren’t compatible.

And remember to take into account the benefits of a lubricated HV pump. It will run more efficiently; however, it also requires more maintenance. The application makes a difference as well. For instance, dry pumps are recommended for laboratory processes.

Making the wrong decision HV pump purchasing decision can be costly financially. Part of that includes a loss of productivity due to extended downtime. To choose the best HV pump, seek a customized solution. A third-party can give you an honest viewpoint from another perspective outside of your organization. HV pump specialists can review your situation and offer valuable insights that you may not have thought of before. Their recommendations may save you money while increasing your facility’s efficient operations.

High Vac Depot is Here to Help!

The experts at High Vac Depot can assist you with selecting the right high vacuum pump to meet your needs. We carry a large selection of vacuum engineering products. We can also special order components. You can get the right HV pump without guessing at it. Call us toll-free at 1-800-289-6945 or fill out our short Contact Us form today!