14
Issue 3 2020
pump systems, pipes & valves
Peristaltic pumps not only for laboratories
O
ne of the fastest-growing types of positive displacement pumps on the market is the peristaltic pump. Once used exclusively in the lab, this pump has been transformed for use in process control, water treatment and plant production. Yet it remains largely unknown to many people, despite its many advantages. The popularity of the peristaltic pump – a.k.a. tubing pump – can be attributed to its design. An electric motor turns a set of rollers, which compress and release flexible tubing as they rotate. This squeezing action creates a vacuum that draws fluid through the tubing. Because the flexible tubing is the only wetted part, maintenance and clean-up is simple and convenient.
irradiation or ethylene oxide gas application, and most systems facilitate steam-in-place (SIP) and clean-in-place (CIP) techniques. This ensures complete sterility of the entire pump system with minimal cost.
Non-contamination The peristaltic pump creates a contamination-free pumping system. The fluid being pumped remains inside the tubing at all times and thus never comes in contact with any pump gears, seals, diaphragms, or other moving parts. As a result, finding a pump compatible with a particular solution is as simple as choosing the correct tubing, which may need to be chemically compatible to the product. This makes peristaltic pumps ideal for transferring chemically aggressive or abrasive solutions as well as high-purity fluids. There is no need to worry about corrosion or wear and tear on parts, and no need to worry about contamination. Moreover, most types of pump tubing can be sterilised through autoclaving, gamma
Low maintenance Peristaltic pumps require very little maintenance beyond tubing replacement. Tubing must be replaced periodically to offset reduced flow performance. This procedure typically takes just seconds, which can be an advantage when using the same pump to transfer or dispense different chemicals. When solutions are changed, only the tubing needs to be changed, and the pump can be up and running within minutes. In addition, many tubing pumps are designed with high Ingress Protection (IP) ratings, which means they can be hosed down for quick, thorough cleaning.
Simple operation Peristaltic pumps are simple to operate and easy to customise. They are self-priming, and many models have interchangeable pump heads that can be mounted in minutes using finger-tightened screws. Engineering advances have yielded designs that allow the tubing even in large process pumps to be loaded or replaced in seconds. In addition, most pumps feature simple controls, with a dial or keypad for speed control, and straightforward menus for programming more complex tasks.
Tubing materials Peristaltic pump systems are compatible with a wide range of tubing materials, including
silicone, thermoplastics, Viton, and even rigid PTFE. There are also newly developed formulations of bi-layer, or co-extruded tubing, in which a long-life tubing material is laid over a thinner inner material that is compatible with aggressive chemicals, resulting in a tubing that’s collective properties in a pump exceed those of either material alone. Many tubing types also meet United States Pharmacopoeia (USP), Food and Drug Administration (FDA), U.S. Department of Agriculture (USDA) and/or National Sanitation Foundation (NSF) agency requirements. This makes peristaltic pumps suitable for handling a variety of fluids, from sensitive cell cultures to industrial solvents, and allows the same pump to be used in multiple applications simply by changing the tubing. Multimedia pumping capabilities In addition to generating enough suction to self-prime, peristaltic pumps create sufficient vacuum to successfully pump most viscous fluids — including those too heavy for other types of pumps. Yet, because these pumps employ a gentle pumping action that leaves
Vacuum solutions for use in laboratory technology, analytics and biotechnology HiPace Turbopumps: For the highest requirements in the analytical market With the HiPace family, Pfeiffer Vacuum, a leader in turbopumps with integrated drive electronics, has established a compact and powerful series in the analytical market. The outstanding feature of these turbopumps is their unique rotor design with the proven hybrid bearing. These technical characteristics make for extremely high pumping speeds, high critical backing pressure and gas throughput, as well as very good compression for light gases. The turbopumps work particularly quietly and with only minimal vibration. The bearings also result in long service intervals and thus a high degree of efficiency. The functional aluminium housing makes the pump extremely light. A sealing gas connection safeguards the bearings against particles or oxidising gases. The result is an optimal integration of the pumps. The long lifespan and the high system availability set new standards. When looking at a successful process of an entire production, vacuum often has a key position. Faulty batches or production downtime, depending on the application, can quickly cost several million rands. All the more important is the maximum
reliability for all installed components. Today, turbopumps often reach an operating life of up to 100 000 hours. This corresponds to an uninterrupted lifetime of about 11 years. Pfeiffer Vacuum turbopumps have advanced diagnostic functions in order to cause as few interruptions as possible for maintenance or service work. Uniquely, the exchange of bearings and equipment in these pumps can be done in the field. The integrated drive electronics for the turbopumps also reduce the effort required for wiring considerably. Advanced drive technology minimises energy consumption, and varied control options are offered. SplitFlow Turbopumps: For the simultaneous evacuation of several chambers The SplitFlow turbopump technology by Pfeiffer Vacuum enables multiple pumping systems to be replaced by a single vacuum system. One single SplitFlow pump can be used as a double or triple inlet pump to simultaneously evacuate two or three chambers of a series-connected mass spectrometer system. Depending on the gas load, small and economical dry diaphragm pumps can be used as backing pumps. This means a significant reduction in investment and operating costs. Another key advantage
is the small footprint of the vacuum system. The pumping speed of the SplitFlow pumps extends generally in the range of 690l/s to 10l/s. Small models with a pumping speed of 10l/s to 0.1 l/s have been designed for portable analysis systems. The SplitFlow pumps are not only used in analytical instruments, but also successfully used in leak detectors, where their analysis principle is also based on mass spectrometry. Multi-Stage Roots pumps ACP: Dry backing pump for particle-free applications The multi-stage Roots pumps of the ACP series by Pfeiffer Vacuum are suitable for all vacuum applications where extreme cleanliness of the vacuum process is required. A special feature of the pump is that the pump system is composed of non-wearing parts. This allows for unmatched durability and high reliability even in demanding applications. The ACP is the oil-free alternative to the traditional oil-sealed rotary vane pump. Since the ACP has no seals between the individual pump stages that wear out and the rotors run without any contact, no seal wear occurs in the pumping system, as is the case with other oil-free pumps. The motor with frequency converter ensures constant performance of the ACP, regardless of mains voltage and frequency.
solid components of the fluid, including cell walls and particulates, intact, they are excellent for moving sensitive fluids, slurries and suspended solids. Peristaltic pumps are also used to move liquids, gases and mixed-phase fluids. If gas bubbles are present in the fluid stream (for instance, through out-gassing from solution), they can be pumped right along with the liquid portion without any flow disruption. For this reason, peristaltic pumps can also run dry without damage. Cost-effective operation Peristaltic pumps are relatively inexpensive to operate. They are cost-effective because they are easy to clean, they are effectively impervious to the most abusive, pumpdamaging chemicals, and because the same pump can be used for multiple applications, this results in lower labour and maintenance costs, less downtime, and increased production. Conclusions Peristaltic pumps have become a critical and reliable part of processes ranging from chemical transfer to pharmaceutical processing to wastewater treatment. Their versatility and ease of use has helped them meet a multitude of fluid-handling challenges.
INSTRULAB - A DIVISION OF AIR & VACUUM TECHNOLOGIES Mark Burn 0861 VACTEC (822 832) info@vactech.co.za www.vactech.co.za
High flow gas ballast ports and external drainable silencers allow the ACP to pump high amounts of condensable vapours (up to 1 000g/h of pure water vapour). Integrated pressure measurement: Direct installation, no special wiring The combination of generating vacuum and measuring vacuum is a new concept in integrated pressure sensors. Very small vacuum measuring sensors are attached to the Pfeiffer Vacuum turbopumps or Pfeiffer Vacuum chambers. The advantage is this combination has only one electrical interface. This allows an easier installation for the user. Complicated wiring, software and hardware adjustments are things of the past. This saves time and money. The sensor communicates digitally with the turbopump, which creates a more reliable pressure signal than via an analogue transmission. This pressure signal can be retrieved along with the status information of the turbopump, such as rotation speed, power consumption, etc. via the RS-485 interface.
AIR & VACUUM TECHNOLOGIES Mark Burn 0861 VACTEC (822 832) info@vactech.co.za www.vactech.co.za
