Many different and varied pump types are in use both in technology in general and in daily life. These can be used to transport all types of materials. The most important pump types include piston pumps, centrifugal pumps, diaphragm pumps and peristaltic tube pumps. If these are used as part of a process, for example to transport fluids, then we speak about mechanical process engineering.
In recent years, it has become ever more important to be able to meter fluid quantities in the microlitre range as biotechnology processes involving higher concentrations of active ingredients have come to the fore to respond to the need for process optimization. These demand high precision on the part of the employed pump technology, coupled with low pressure and volumetric flow pulsation, a high level of resistance against many different types of fluids, and the greatest possible service life. This pulsation-free metering of fluids by peristaltic pumps has been made possible, for example, through long-term perfusion trials in the field of pharmaceutical biotechnology. In these trials, the organs that are being examined are continuously perfused with solutions using peristaltic pumps. These pumps are also perfectly suited for applications involving fermentation and cell cultures in bioreactors.
All these desirable pump properties are provided by modern peristaltic pumps, such as those manufactured for more than 30 years by SPETEC, a company based in Erding/Germany.
Laboratory pump version: Perimax 12/16
SPETEC designs and builds these peristaltic pumps for a wide range of applications and also produces the associated tubing, which is available in many different materials. The materials PVC, Santoprene and Silicon are the most suitable for dilute acids as well as for water-based solutions. Fluorinated rubber tubing is generally used to transport concentrated acids and the most common solvents. SolventFlex tubing is used for the metering of alcohols, petrol, diesel and kerosene.
The aims during the design and development of a peristaltic pump are exceptionally constant metering, extremely stable technical functioning and, depending on the application, the lowest possible pulsation levels. These are the criteria underpinning the design of the two laboratory pump variants Perimax 12 and Perimax 16 which differ in the number of rollers (12/16) in the pump head and the continuously adjustable flow rates they can achieve (0.0017 mL/min to 20 mL/min against 0.0034 mL/min to 40 mL/min). The 16-roller pump produces no measurable pulsation since the 16 rollers are subdivided into 32 units that are mounted phase-shifted relative to one another. As a result, dual pump tubing must be used when the Perimax 16 is used to transport media. This takes the form of two tubes that are coupled together by means of a Y-piece and are each guided via a half-channel. Thanks to this arrangement, the peaks and troughs cancel one another out, thus resulting in a pulsation-free flow.
Another important characteristic of SPETEC pumps is their ease of use and maintenance. The selected tubing is guided around the pump head and its two ends are fixed to a special mechanism. The compression level can be set using an adjusting screw at the adjusting lever. The pump is switched on and off and the direction of rotation (left or right) is selected using pushbuttons. The speed of rotation of the pump head is continuously adjustable using a 10-turn potentiometer. A button is available to briefly activate the highest operating speed, for example for the rapid rinsing of the tubing when switching over to a different fluid. The drive unit used in the two pumps is identical. The extremely constant rotation of the low-wear stepper motor and the high-precision optoelectronic controller guarantee uniform fluid transport. Thanks to a rear-mounted, 9-pin Sub-D connector, the speed and direction of rotation can be controlled externally by means of an analog signal. All the pump`s external parts are made of stainless steel or PVC or are plastic-coated. This ensures a very high level of corrosion resistance.
Use of the custom-built pump versions in research institutes and laboratories
Our OEM pumps have proved their worth in the field of instrumental chemical analysis, in particular in the case of spectrometric methods such as ICP analyses. An Inductive Coupled Plasma device is an analytical system which makes it possible to identify the quantities of many different elements present in a solution. The task of the peristaltic pump is to ensure the low pulsation metering of the substance for analysis into the nebulizer which disperses the solution as a fine mist that is introduced into the plasma. In the plasma, the individual atoms are ionized and result in an atomic emission which can be recorded both qualitatively and quantitatively using spectrographic and spectrometric systems. The use of peristaltic pumps has also proved to be of great value in the fields of biotechnology, bioanalysis and in column chromatography applications.
SPETEC`s OEM (= Original Equipment Manufacturer) pumps are not manufactured as series products but are designed and built individually on request. Only a few of the basic components, such as the roller heads, pressure brackets or clamp mechanism, are identical.
Because these pumps are constructed for use in another manufacturer`s end products, they must be custom-built. This means that they must also meet the customer`s requirements in terms of visual design. This applies to the color and geometry of the mounting plate on which the pumps, which may possess differing numbers of channels, are fitted, as well as to the basic components whose coloring is also adapted to match the device in which the pump is to be installed. The units are design based on the customer`s wishes. Thus the custom-designed baseplate can be fitted directly to the housing of the analysis unit or can be integrated in the device construction. This makes the custom-built peristaltic pumps easier and more economical to install during the final assembly of analysis units. Consequently, there are many different variants.
In all the models, the drive unit is constructed using a stepper motor with the aim of achieving the greatest possible stability in terms of pump speed and uniform flow rate, as well as the lowest possible pulsation level SPETEC not only takes account of the individual demands placed on its pumps but also places value on their attractive appearance.
The Minipump which was adapted to respond to the trend toward ever smaller analysis units, is a typical customer-oriented design. Peristaltic pumps can nowadays be engineered to a high level of precision provided that the corresponding experience is available. Because the generation of the suction pressure depends to a very great extent on the selected tubing material, this is of crucial importance in guaranteeing a constant, low-pulsation fluid flow. Beside the quality of the tubing material and the type of fluid to be transported, the diameter of the pump head and the pressure rollers also has a considerable impact on the service life of the tubing. By choosing the correct design parameters, it is therefore possible to greatly prolong the lifetime of the tubing. As a result, the flow rate remains constant for longer and pulsation levels are kept to an absolute minimum. The production of the tubing is an important criterion making it possible to maintain these high quality standards. Thanks to its decades of production experience, Spetec has acquired the necessary expertise in the design and selection of the tubing material.
