Types of Industrial Vacuum Pumps
Industrial vacuum pumps are designed to pump gasses and liquids out of sealed containers to create a vacuum. Though this technology has been explored since the 17th century, it has only recently expanded to a range of industries. From household electronics to aircraft equipment, vacuums are needed in countless applications.
While vacuum pumps are all designed to create vacuums, different types of pumps create different outcomes. Pumps that work well in one environment or application may fail in another setting. Knowing the right type of vacuum pump for a specific application is essential to keep systems running properly.
Types of Vacuum Pumps
All vacuum pumps operate on the same principle — they remove air and gas molecules from a vacuum chamber. While all pumps are designed to accomplish this goal, their methods differ.
Vacuum pumps are split into two primary classifications:
- Positive displacement pumps create vacuums by acting on a constant volume of air and generate high vacuum with little flow.
- Nonpositive displacement pumps accelerate air out of a system to create a vacuum at an inlet port but generate little vacuum with high flow.
Many vacuum pumps are positive displacement pumps, and they are further divided by their function. Some of the mostcommon types of industrial vacuum pump systemsare:
1. Rotary Vane Pump
Rotary vane pumps are positive displacement pumps that work through the use of rotating vanes in a cylindrical case. As these vanes slide in and out around the eccentrically mounted rotor, the pump traps air and moves it from the inlet port to the outlet port, generating vacuum. In total, rotary vane pumps typically generate 20 to 28 inHg, though some two-stage designs gan generate up to 29.5 inHg vacuums.
- Advantages: Rotary vane pumps are effective, compact and inexpensive. Though these pumps are small compared to other types, they have a high flow capacity for their size and are much less expensive than pumps with similar vacuum levels. Additionally, they operate very smoothly and quietly without vibrating, generating as little as 45 dBA of sound.
- Disadvantages: Rotary vane pumps are in the middle-ground of vacuum pumps — they aren’t as powerful as other types, like piston pumps.
- Applications: Because of their compact nature and efficacy, rotary vane vacuum pumps can be found in a variety of industries, especially in environmental, medical and commercial industries. They are commonly used in air conditioning and aeration systems, but may also be found in food processing, surgical suction and even pond aeration applications.
2. Rocking Piston Pump
Rocking piston pumps are positive displacement pumps that use a rigidly mounted piston and an eccentric connecting rod. As the crankshaft rotates, the piston rocks back and forth, pushing and pulling air with an elastomeric cup serving as a seal. A single pump produces a vacuum to 27.5 inHg, while a two-stage design can generate up to 29 inHg.
- Advantages: Without the wrist pin found in diaphragm units, rocking piston vacuum pumps are much lighter and more compact than many other options. They are also relatively quiet during operation, operating at sound levels as low as 50 dBA.
- Disadvantages: Rocking piston pumps cannot generate much airflow — even the largest models have flow rates under 10 cfm.
- Applications: Rocking piston pumps are commonly used in pond aeration systems, but their quiet operation makes them a good choice for noise-sensitive environments like medical, dental and laboratory applications. Rocking piston pumps are also used in beverage dispensing systems, automotive suspension systems and even paper counting machines.
3. Reciprocating Piston Pump
Reciprocating piston pumps have one or more pistons attached to a rotating crankshaft. As the crankshaft turns, the pistons reciprocate, and the alternating piston action moves air to create a vacuum. These positive displacement pumps generate relatively high vacuums from 27 to more than 29 inHg.
- Advantages: Reciprocating piston pumps generate relatively high vacuums and work well in a wide variety of operating conditions. They also have long lifespans.
- Disadvantages: The primary disadvantages of the reciprocating piston pump system are that they are heavier and more expensive than many other systems. They also have limited capacity and typically operate at higher noise levels than other systems.
- Applications: Reciprocating piston pumps are best suited for applications in harsh conditions, making them ideal for volatile applications and the petrochemical, menthol and aromatic industries.
4. Diaphragm Pump
In diaphragm pumps, the fluid chamber is sealed from the pumping mechanism. Instead, an eccentric connecting rod flexes a diaphragm inside this chamber, which generates the vacuum. Diaphragm pumps provide moderate vacuums, with single-stage versions reaching up to 25.5 inHg, and two-stage units reaching 29 inHg.
- Advantages: Diaphragm pumps have a low compression ratio with low flow, large diameter and short strokes. This means these types of pumps operate very quietly. They are also exceptionally reliable and cost-efficient.
- Disadvantages: Diaphragm pumps produce somewhat lower vacuums compared to other positive displacement vacuum pumps.
- Applications: These types of pumps are very popular in the medical industry due to their reliability and quiet operation. They are often used for blood pressure monitors, breast pumps, sterilizers, aspirators and various types of mobile equipment. They are also commonly found in air and water sampling, water purification and general laboratory equipment.
5. Dry Claw Pump
These positive displacement vacuum pumps use two claw-shaped rotors, which run in opposite directions. These rotors do not touch each other or the pump chamber, meaning that they sustain less wear over time.
- Advantages: Dry claw vacuum pumps have long lifespans due to their low-wear designs. They also do not use lubrication, which eliminates contamination of processed substances. They are also some of the quietest pumps on the market.
- Disadvantages: Dry claw pumps are heavy systems designed for industrial applications, so they are not suitable for smaller-scale applications. They also work poorly at higher altitudes.
- Applications: Dry claw pumps are designed for industrial environments and are commonly found on production lines, pneumatic systems and central vacuum supply systems.
6. Liquid Ring Pump
Liquid ring pumps work using an eccentrically-mounted impeller with multiple blades. As the impeller rotates, it moves liquid inside of its case to form a liquid ring. The expansion of the air space during this rotation creates a vacuum, which is used to compress and discharge air at rapid speeds.
- Advantages: Liquid ring pumps are effective at absorbing the heat generated during the compression process. The liquid in the system also serves as a way of trapping any powder or liquid in the air. These pumps are also known as some of the quietest in the industry, producing around 75 decibels.
- Disadvantages: Liquid ring pumps are larger in design and are best suited for large-scale industrial installations.
- Applications: These pumps are most often used in industrial applications, most often in applications that benefit from the air-purifying properties of the liquid-ring design. Some examples include the chemical, environmental, mining, petrochemical and textile industries.
7. Rotary Screw Pump
Rotary-screw vacuum pumps are positive displacement pumps. In this design, two helically-shaped rotors turn in opposite directions, trapping air and moving it through the chamber to create a vacuum. Though this design allows for high airflow, it achieves relatively low vacuums limited to about 15 inHg.
- Advantages: Unlike piston pumps, screw pumps work through a smooth, continuous motion, which means the pumps do not have the pulses often seen with piston-based designs.
- Disadvantages: Due to the size of the necessary parts, rotary screw pumps are cumbersome at smaller sizes. As a result, they are most often seen in larger installations. They also do not produce as much vacuum as piston-based designs and have lower inlet capacities. Additionally, screw pumps sometimes encounter issues with lubricant migrating into the pumping chamber over time, which can result in maintenance problems.
- Applications: These pumps are often found in large-scale industrial applications that handle clean gasses.
High vs. Low Vacuum Pumps
In addition to the various types of industrial vacuum pump systems, pumps are also split into categories by the amount of vacuum they can generate. Levels of vacuum are divided into four levels defined by the level of pressure within the vacuum chamber. These are represented below in torr units of pressure, though mmHg is also commonly used. For reference, one unit of torr is equal to 1/760 of atmospheric pressure.
The categories of vacuum are as follows:
- Low vacuum: Low vacuum is any pressure level above one torr. All vacuum pumps can achieve this level, and most mechanical vacuum pumps operate within this range. Also called a rough vacuum, the majority of industrial-level vacuum units are considered low volume vacuum pumps and generate this level of vacuum.
- Medium vacuum: A medium vacuum has a pressure level between one and 10-3 torr. Most pumps providing this range are mechanical. Process application vacuum units are typically made to produce this level of vacuum — this includes vacuums made for spraying or gas removal processes.
- High vacuum: High vacuum is indicated by pressures between 10-3 and 10-7 torr absolute — any lower than 10-7 torr is considered very high vacuum. High vacuum is only required in specialized industrial and lab applications and is often achieved through the use of non-mechanical vacuums. Very high vacuums are even more specialized, needed mostly in laboratory applications and space simulations.
How to Choose the Right Vacuum Pump
Choosing between the different types of vacuum pumps can be difficult with so many options available. The choice often comes down to a few factors, such as:
- Level of vacuum: The level of vacuum needed is one of the primary factors to consider. These categories tell the user how much vacuum the pump can generate.
- Usage: Larger units are typically designed and rated for continuous duty, while smaller units are made for intermittent duty. Smaller units applied in a continuous manner typically encounter functional limitations that decrease their vacuum generation capabilities.
- Rate of removal: Pumps are flow rated based on the volume of air they can handle. High flow rates mean that the pumps can remove air more quickly.
- Power requirement: Vacuum pumps typically require little power input, but not all pumps are made the same. Though the power requirement for a unit doesn’t necessarily affect functionality, it does affect your business’ power usage and efficiency.
- Time: If it is essential that a certain vacuum level is achieved within a specific time frame, a high volume vacuum pump will be the best option. If time is not important, a small pump will suffice.
Common Vacuum Pump Applications
Vacuum technology is everywhere in industry, with businesses relying on vacuums for a range of processes and production methods. Some common examples are:
- Automotive: Vacuums are required in the function of vehicles and in their production and maintenance. Cable pressure and automotive suspension systems are often maintained using vacuum systems, while auto detailing and tire inflation equipment use vacuum pumps to build pressure for their systems.
- Medical: Vacuum pumps are used in a wide range of applications throughout the medical industry. Various types of ventilation equipment and oxygen concentrators use pumps for respiratory therapy applications. Surgical teams also use vacuum pumps to power various types of equipment and sterilization systems. Even medical pumps themselves, including breast pumps, and suction units, use vacuum pumps.
- Dental: The dental industry commonly uses a range of vacuum pumps in various applications. Dental compressors and portable dental equipment often use vacuum pumps to build pressure in systems, while vacuum ovens are used to mold implants.
- Environmental: Air sampling and soil aeration equipment both use vacuum pumps to power their processes. Vacuum pumps are also an essential part of any air supply system or sewage aeration system.
- Food and beverage: Food processing and water purification systems often use vacuums as part of their processes. From aeration and mixing to packaging, vacuums are used throughout this industry.
- Agricultural: TheAgriculture industry often uses vacuum pumps in the development and application of agricultural sprays. Pest control equipment and crop sprayers are often powered by vacuum pumps. Milking equipment also uses vacuum pumps.
- Electronics: Many electronics require vacuums to function. The most common example is the electric lamp — light bulbs require a vacuum in order to function, so a vacuum pump is needed to take gas from the bulb. Semiconductor production also requires the use of vacuums.
- Arts and printing: Airbrushes, ink-jet printers, framing equipment and other staples of the printing arts are powered by vacuum pumps.
Choose RG Group
With so many industrial vacuum pump sizes and types available, it’s important to know your options. Different technologies can be used to generate a reliable flow of vacuum, but no single technology achieves optimal efficiency at every level of vacuum. The right type of vacuum pump will serve your application smoothly, while the wrong one may result in significant costs and future down-time. We know that the choices can be overwhelming, so RG Group is here to help.
For over 60 years, RG Group has been an industry expert in vacuum technology solutions, providing trusted expertise in selecting and installing solutions from a variety of manufacturers. We offer an extensive line of air-moving products from industry-leading manufacturers GAST and Atlas Copco., including Gast vacuum pumps, compressors, air motors, gear motors, vacuum generators, and regenerative blowers. By combining the two global leaders, the RG Solution incorporates a wide variety of vacuum pump models to choose from, ensuring you’ll be able to find the right one for your applications.
Whether you need a simple fix or a custom solution, RG Group can help with our team of experts and our global network of sales representatives, service facilities and distributors. Whether you’re located in the United States, Europe or China, we can help you get the parts and services you need.
Contact RG Group today to learn more about our fluid handling and motion control solutions, as well as our quality industrial parts and services.