Roadmap for vacuum in the laboratory


Catalog excerpts

Roadmap for vacuum in the laboratory - 1

ROADMAP... ...FOR VACUUM IN THE LABORATORY Technology and applications for chemistry and life science

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Roadmap for vacuum in the laboratory - 2

FOREWORD Unbelievable but true, a technology with which you literally produce “nothing” belongs to a widespread key technology. Whether at home whilst vacuuming in the manufacture of various goods, in automation or in the laboratory, vacuum technology is used everywhere. On the following pages we will focus on the laboratory and provide you with an overview of the special requirements that vacuum technology fulfils and the technical solutions that are most appropriate. “The right tool saves time” – this old saying of craftsmen applies not only to the building site, but also in the...

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WHY VACUUM? Many people use vacuum every day in the laboratory. But what is the actual purpose behind it? Vacuum is used for many standard applications in the preparation and processing of samples. In most cases, the vacuum is not the focus, but it is absolutely essential. The most well-known applications for vacuum are vacuum filtration and drying. Of course, you could filter without vacuum as well - like brewing coffee - by letting gravity do the work for you. However, whilst this may work for coffee, it does not always work in the laboratory like this because of the broad spectrum of...

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REQUIREMENTS FOR VACUUM TECHNOLOGY The requirements for a vacuum are always dependent on the individual application and the use of very different solvents and substances. Characteristics such as boiling point, corrosion hazard and the quantity of the solvent to be evaporated play an important role in the selection and size of the appropriate vacuum equipment. For example, whether it is Methanol, Dimethyl Sulfoxide (DMSO) or a complex mixture that is to be evaporated at a certain temperature presents a critical difference since these substances all have different boiling points. Therefore,...

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Depending on the respective pressure range, different pump technologies are used for vacuum creation. While the rough vacuum range can be covered most efficiently with diaphragm pumps, rotary vane pumps are frequently used in the creation of fine vacuum. Outer Space High vacuum systems with backing pumps Extremely high vacuum (XHV) Rotary vane pump technology Diaphragm pump technology Fine vacuum Rough vacuum Fig. 1: Pressure ranges and technologies Applications of fine vacuum Applications of rough vacuum + residual drying in Schlenk lines + solid phase extraction + evacuation of the sample...

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The pumping speed is indicated in cubic meters per hour [m3/h] or litres per minute [l/min] (1 m3/h ≙ 16.6 l/min). The greater the pumping speed, the faster the pump can evacuate a certain volume. When comparing the maximum pumping speed of two pumps, this is always measured under atmospheric pressure conditions, because as the pressure reduces, the pumping speed is also reduced since there are fewer and fewer molecules that can be “evacuated”. The extent of this loss of performance differs from pump to pump and very much depends on the pump technology used. If the pumping speed is to low...

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Designed for demanding chemical processes Using corrosion-resistant pumps is critical in chemistry labs. This is guaranteed first and foremost by the use of chemical-resistant plastics and special pump head technology. Work in chemistry labs typically involves flammable solvents. To ensure safe operating conditions, most VACUUBRAND chemistry diaphragm pumps have a Category 3 ATEX rating on the inside parts that come into contact with the media. These pumps can be used without problem to support normal lab-scale work with nearly all common lab solvents Fig. 3: Ex-Zone 2, internal atmosphere...

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TECHNOLOGY There are a variety of technical solutions for the requirements just described. At first glance, these differ based on the pump technology used as well as the number and connection of the pump heads. Here, the term pump head refers to the chamber in the pump through which media are pumped, and the adjacent mechanical components (Fig 4). However, the performance and robustness of a pump is also highly dependent on the construction and quality of the materials used. Additional distinguishing features arise from the accessories used. There are significant quality differences,...

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Housing cover Valves Head cover Pump chamber Diaphragm clamping disk Diaphragm Diaphragm support disk Connection rod Excentric shaft Fig. 4: Schematic representation of a diaphragm pump It is crucial that the materials used in the pump head are chemical-resistant. Special fluoroplastics which have a high long-term stability and density are used for the manufacture of each of the different parts in the pump head (Fig. 5). Although fluoroplastics are extremely chemically resistant, they are not very mechanically stable; therefore, a metallic stability core inside is extremely important. (You...

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In a rotary vane pump, an eccentrically mounted cylinder with sliding vanes rotates within the cylindrical pump chamber, thus pushing the inflowing gas in the direction of the exhaust. After a certain point in the rotation, the eccentric position leads to the gas being compressed by the movement of the vanes (Fig. 6). As soon as the gas pressure exceeds the opening pressure of the outlet valve, the gas escapes through the exhaust. Oil is used here for lubricating and sealing the vanes to the metal cylinder. Fig. 6: Construction of a rotary vane pump Fig. 7: Rotary vane pump RZ 2.5 The...

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In this instance, a hybrid chemistry pump is a very good alternative. This consists of a rotary vane pump combined with a chemical-resistant diaphragm pump that constantly evacuates the oil aggregate during the process, thus extracting the corrosive vapours and condensates from it. Single-stage or multi-stage? The ultimate vacuum and the suction capacity of a pump depend on the modular connection of the pump heads. A parallel connection of the pump heads causes an increase in the pumping speed, while a serial connection leads to a better ultimate vacuum - i.e. a lower ultimate pressure...

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