ISP Oil-Free Vacuum Design Delivers "Clean" Processes and "Green" Results
By even the most rudimentary definitions, vacuum is not the presence but rather the absence of something, of anything—including color. Whether vacuum is utilized for analytical purposes in corporate R&D or in government or university laboratory settings, those who depend on vacuum pumps to create and maintain that absence do not expect vacuum to have color. However, in very significant and measurable ways, vacuum can be green.
But first, an anecdote
About a year ago, a plaid-shirted professor from a well-known research university was trolling the aisles of a conference and expo, looking for ways to improve his lab. He was in search of something that would make a difference not only to the world of scientific research, but also to the world of university trustees and budgets. His particular area of research required rough vacuum and, for years, he had been using “wet” pumps, which were easy on his budget and had given him satisfactory results. As he explained all this to the representatives at a particular vendor booth showcasing “dry” vacuum pumps, he asked them to explain the benefits of their particular type of rough vacuum pump. A simple phrase mentioned repeatedly in the booth, both by those with whom he spoke as well as the accompanying literature, particularly piqued his interest.
The phrase was “oil-free.”
You see, the professor had found himself spending valuable research time and money changing contaminated and spent oil on a monthly basis, plus he had to deal with increasingly stringent requirements and costs for the oil disposal. As the reps at the booth continued to iterate the benefits of “oilfree” and describe additional benefits of the pumps, the professor, after 10 minutes or so, finally interrupted, saying, “Guys, it’s the oil-free thing.”
For this professor, as well as for many others involved in R&D and manufacturing, producing the vacuum they needed had produced colors they didn’t—colors like the brown or black of spent oil, the red of overdrawn budgets and the flushed-inanger faces of bottom-line watchdogs, and the black and white of the press generated by the ecologically concerned. For many years, the colors of rough vacuum pumping were considered necessary but unavoidable by-products. Sure, there were pumps available that would minimize these colors, but the cost was prohibitive and the early versions of such pumps seemed fraught with problems.
However, even in the infinitely small world of molecular conductance, the winds of change were blowing, carrying with them a better color of vacuum—the color green.
Green by design
The quality and quantity of the green produced depend on the design of the instrument of delivery, e.g., the vacuum pump. Three basic designs exist in the oil-free scroll vacuum market: the dual path, single path and cantilevered (expansion, then compression) designs. In the dual path design (Figure 1) the gas path is split into two equal components compressing in parallel, while in the cantilevered design (Figure 2) there is one gas path divided into two different stages—expanding and compressing. This single path design is like the dual path design but has only one compression path that produces varying torsional and side-to-side loads. The dual path design, originated and patented by Anest Iwata of Japan, clearly produces the better green vacuum, as described below.
Figure 1.
Reduced maintenance—costs and frequency
Imbalance within the pump will cause uneven pressures and therefore accelerate wear on bearings, crankshafts and scroll surfaces, necessitating more frequent (and often more costly) maintenance repair. The ISP Iwata Scroll Pump (ISP) design, the original oil-free scroll vacuum pump from Anest Iwata, reduces maintenance costs and frequency of maintenance by addressing the issue of imbalance in scroll pumps. First, counter mass balance in differing weights of the two fans, one on each end of the crankshaft, addresses the momentum imbalance created by the orbiting scroll. Second, the dual gas path eliminates axial imbalance because the orbiting scroll floats on equal gas pressures. The resulting lower torsional forces and lower tip seal forces not only extend the meantime between maintenance, but also reduce noise and vibration. The manufacturer recommends maintenance intervals of up to two years, depending on the particular application.
Figure 2.
Anest Iwata ISP-500 Oil-Free Scroll Vacuum Pump
Reduced energy consumption—operations and design
Accurately described as “the original oil-free scroll vacuum pump,” the ISP design does not use oil, thereby not only reducing energy consumption in oil production/ usage, but also eliminating costs associated with disposal of contaminated oil. (Our professor from the earlier anecdote was quick to appreciate the value of this.) Rather than consumable and costly oil lubricants, specially designed, long-life tip seals serve as the lubricant for the orbiting scrolls. Additionally, these pumps are air-cooled, eliminating the need for water-based or additional external cooling systems. Finally, due to the balanced nature of the orbit of these scrolls, as described earlier, the ISP-design scroll vacuum pumps run more efficiently, thus lowering operating costs associated with energy consumption.
Reduced contamination—in process and the environment
Historically, one of the major concerns in the application of rough pump vacuums has been contamination due to back streaming and its accompanying destruction of materials, time and finances. The ISP design, having eliminated oil from the gas path of the rough pump, effectively eliminates the concerns associated with oil back-streaming contamination. In the greater context of conservation and preservation, the ISP oil-free design addresses the growing problem of waste oil disposal. New local, state and federal standards are already in place (or soon will be), not only requiring responsible use and reduction of use of carbon-based fuels and lubricants, but also demanding lab and manufacturing responsibility (read: “liability”) for the life of the product. The ISP oil-free scroll vacuum pump effectively reduces contamination on two fronts: placing the user in a process “clean” and ecologically “green” position.
Expecting color in vacuum
One could argue that there really is no expectation of color in vacuum. In fact, one would say that the expectation and the very goal of vacuum is nothing.
Yet wherever and whenever we attempt to produce vacuum, color will be present. None of the colors we’ve come to expect (dare we say dread?)—red, black and brown—are desirable.
Check out companies like TSO3 (featured in Venture magazine, 30-34, September/October 2007) that are turning to ISP-version oil-free scroll vacuum pumps to manufacture environmentally safe and cost-effective sterilization processes for hospitals.
The better color of vacuum is green. It is also the color that has come to be expected and a color whose design for delivery is already here.
