A vacuum pump is a device that pulls air or gas from a tank in order to generate a partial or full vacuum in the system. A steady reduction in pressure in the restricted area draws in the air. The inhaled gaseous molecules are subsequently released into the surrounding environment or into another tank.
They’re utilized in a variety of industries, including labs, the medical business, food packaging, and the chemical industry.
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How to choose a vacuum pump?
Many things must be considered while selecting a vacuum pump. First of all, your choice should be adapted to your intended use, this will allow you to determine the technology , lubrication, chemical resistance, vacuum level, and flow velocity required.
The quality and durability of a vacuum pump should be the primary considerations in your purchase. desired vacuum level . There are several types of vacuum: a rough or low vacuum , a high vacuum and an ultrahigh vacuum . The difference between the three lies in the scarcity of the number of molecules obtained, which is measured by the pressure of the residual gases. The lower the pressure, the lower the number of molecules per cm3. As a consequence, the vacuum’s quality has improved.
We refer to:
| Vacuum type | Maximum pressure (in mbars) | Minimum pressure (in mbars) | Molecules per cm³ |
| Rough vacuum | 1 | 10-3 | 1016 – 1013 |
| High vacuum | 10-3 | 10-7 | 1013 – 109 |
| Ultrahigh vacuum | 10-7 | 10-12 | 109 – 104 |
You will also need to consider the following characteristics:
- the pump’s flow rate The flow rate is proportional to the machine’s draining time. It is therefore necessary to evaluate the capacity of the vacuum pump to produce both the required pumping speed (volume flow rate) and the mass flow rate according to the process requirements. In general, the faster the draining time, the greater the flow rate. The table above displays the number of surviving molecules per cm3 for each vacuum type.
- chemical compatibility It is essential to evaluate the compatibility of the gases used in your application with the vacuum pump of choice by examining any potential difficulties that the device may meet.
- lubrication : it is essential to ask yourself whether or not it is necessary to lubricate the vacuum pump. Lubricated vacuum pumps are more efficient and resistant. It does however require very regular maintenance. A dry vacuum pump is ideal in a laboratory setting.
- maintenance and cost : based on the criteria listed above, it will then be necessary to analyze the frequency of maintenance cycles. This will decide the ultimate cost of your installation, which must include not only the purchase price but also the expenditures of operation and maintenance.
Main points
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- vacuum level
- flow rate
- lubrication
- chemical compatibility
- maintenance
What are the main types of vacuum pump?
There are five main types of vacuum pump:
- rotary vane vacuum pumps
- diaphragm vacuum pumps
- liquid ring vacuum pumps
- scroll vacuum pumps
- turbomolecular vacuum pumps
The sort of vacuum needed, as well as the price and durability of the necessary technology, will influence your choice of vacuum pump.
When should you use a rotary vane vacuum pump?
Pfeiffer Vacuum rotary vane vacuum pumpIf you need a high-performance vacuum pump at a cheap cost, we propose a rotary vane vacuum pump.
Rotary vane vacuum pumps are tiny and compact, yet they can achieve high levels of suction. rough vacuum . They work especially well with watery samples and high-boiling solvents. Vapors can be captured before they even come into contact with the pump.
Oil is required for the operation of rotary vane vacuum pumps. The presence of oil ensures perfect airtightness, constant and efficient lubrication of the moving parts and excellent heat dissipation for cooling the vacuum pump.
Regular maintenance, on the other hand, is required to guarantee the pump’s effective performance. One of the disadvantages is the need to regularly change the oil in order to reduce the risk of wear. It is advised that you replace it after 3,000 hours of usage.
Main points
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- low cost
- small and compact
- lubricated
- high performance
- high vacuum level (1,000 mbar)
- high flow rate: up to 1,600 m³/h
When should you use a diaphragm vacuum pump?
Diaphragm vacuum pumps are particularly corrosion and chemical resistant. For this reason, they can be used for any type of viscous, acidic and corrosive product.
This feature means that diaphragm vacuum pumps are commonly used in fields such as the food industry (for pumping fluids such as water, chocolate and syrups, for example), but also the cosmetics industry (for creams and gels) and the chemical industry. They are also utilized for rotational evaporation and volatile compound treatment. They are also suited for continuous operation.
Diaphragm vacuum pumps also have the benefit of being dry pumps. This means they do not have to be lubricated with oil and maintenance costs are much lower than with a rotary vane vacuum pump. Nevertheless, these pumps are somewhat costly to buy. Another important point is that the vacuum level of diaphragm pumps is lower than that of rotary pumps and is therefore not suitable for freeze-drying.
Main points
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- dry pump
- expensive
- little maintenance
- chemical resistance
- continuous operation
- a lower vacuum level than rotary vane pumps
- low flow: up to 20 m³/h
When should you use a liquid ring vacuum pump?
Liquid ring vacuum pumps operate by supplying a liquid that is centrifuged on the pump walls. This produces a liquid ring that keeps the pump airtight.
Liquid ring vacuum pumps have many advantages that may be useful if you work in industries such as distilleries, petroleum refineries, power plants, mines, sugar factories, etc. These vacuum pumps are not very sensitive to liquids, tiny solid particles, or vapors. Additionally, their isothermal compression is ideal for explosive and heat-sensitive products, which ensures a high level of safety. Vacuum filtration, moisture extraction, water removal from pulp during paper production, mineral recovery, and ash management are all applications for liquid ring vacuum pumps.
With a maximum flow rate of 30,000 m³/h These strong pumps enable you to change the pressure. Nevertheless, we advise you to pay attention to the saturated vapor pressure of the liquid ring. The minimum pressure of the vacuum pump must not be lower than the saturation pressure of the liquid ring, otherwise the liquid ring may vaporize. This will affect the airtightness of your vacuum pump.
Main points
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- dry pump
- high corrosion resistance
- flow rate up to 30,000 m³/h
- high power consumption
- cumbersome
When should you use a scroll vacuum pump?
Edwards scroll vacuum pumpScroll vacuum pumps are used to pump clean and dry vacuums. They are therefore used widely in the research field and in laboratories.
Scroll vacuum pumps pump and compress liquid or gaseous media using two spiral-shaped scrolls. One spiral is stationary, while the other circles it eccentrically. The gas may be squeezed because of this eccentric movement.
Scroll vacuum pumps are small, silent, and do not need oil. The joint spiral creates the vacuum pump’s airtightness. Regular maintenance is necessary, as the seal must be replaced often to ensure optimal airtightness. The main disadvantage to these pumps is their vulnerability to debris and introduced particles that tend to erode the spiral seal.
Main points
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- compact
- without oil
- quiet (50 dB)
- more effective (no dead space)
- vulnerable to debris and introduced particles
- flow rate up to 42 m³/h
When should you use a turbomolecular vacuum pump?
Turbomolecular vacuum pumps can achieve pressures of 10-12 mbar. Flow rates range from 50 l/s to 5,000 l/s. They work in the same way that compressors do. An electric motor operating at high speed rotates the blades of the pump’s various levels, removing air from the volume to be emptied. To accommodate high spinning speeds, these pumps are often installed on magnetic bearings. They necessarily require a primary pump with a vacuum limit of 10-2 mbar.
The absence of oil is a benefit of turbomolecular vacuum pumps. As a result, they are clean pumps. These pumps are ideal for ultrahigh vacuum applications like analytical instruments or laboratory analysis.
Due to their complex technology, these pumps are expensive to purchase and may require more maintenance than traditional vacuum pumps. Pumping speed is also heavily influenced by the kind of gas being pumped. With lighter gases, the speed decreases dramatically.
Main points
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- flow rate from 50 to 5,000 l/s
- pressure from 10-² mbar to 10-¹² mbar
- clean pump because it does not use oil
- pump primer required
- expensive purchase price
- high maintenance costs
How to choose between a vacuum pump without oil and a lubricated vacuum pump?
Another factor that will impact your decision is the vacuum pump’s lubrication. Whether you need to lubricate a vacuum pump or not plays a role in the maintenance level of the machine.
Lubricated vacuum pumps are more robust and efficient, but they need routine maintenance every 12 hours. A cold trap is also recommended since the oil tends to condense steam and reduce the pump’s capacity. This device, positioned at the pump input, prevents oil vapor from rising above the vacuum. If you do not utilize a cold trap, we suggest that you verify the color of the oil used to lubricate the vacuum pump on a regular basis. Another disadvantage of lubricated vacuum pumps is that they cannot be used in certain industrial sectors such as the food industry because the oil can contaminate the food.
Dry vacuum pumps are vacuum pumps without oil . As a result, there is no chance of lubricating media contamination of the product. If you operate in the agri-food business, dry vacuum pumps are especially suggested. These vacuum pumps, however, are more susceptible to moisture, and since there is no cooling liquid, they are more susceptible to high temperatures.
advantages to lubricated vacuum pumps
- low level of wear
- high performance level
ADVANTAGES TO DRY VACUUM PUMPS
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- no contamination
- little maintenance
What are the main uses for vacuum pumps?
Vacuum pumps are utilized in a variety of applications. They are mainly found in laboratories, the medical and pharmaceutical industries, filtration and mass spectrometry.
Each of these applications necessitates the use of a certain kind of vacuum. For example, mass spectrometry requires pressures ranging from 10-3 to 10-4 mbar. It is consequently unnecessary to use equipment capable of producing an ultrahigh vacuum.
A harsh vacuum is required if your application involves the agri-food business, drying, vacuum metallurgy, or distillation.
We propose switching to a high vacuum if you are participating in vacuum mixing or beam welding.
But, whether you work on surface state physics or particle acceleration, an ultrahigh vacuum is recommended.
Applications
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- laboratory
- medical industry
- pharmaceutical industry
- filtration
- mass spectrometry
- handling and lifting
- chemical industry
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