Amplitudes of vacuum pump operation are quantified as maximum allowed inductance, and can range from a low value (>=0.2 Ω) for a critical application (e.g. piping) to as high as 0.3 Ω for extremely heavy duty applications (>=4 mm ID flange). While a larger capacity would increase the pumping efficiency, a smaller pump would allow for higher peak pressure. While these pressures are potentially exploitable, they require either thicker steel piping or additional vacuum-retaining fittings.
As a general rule, smaller pumps perform better and costlier, whilst larger pumps tend to be more reliable and naturally extend the operating pressure range of the system, whilst also adding a greater degree of versatility.
Figures 1 & 3 show exemplary pressure ranges for a vacuum pump in a series configuration. These are restricted to pressures within the critical operating range discussed previously, between 1 to 10 Torr of pressure. There are some important considerations here, with specific consideration being given to the design of the circuit connecting the internal chamber to the external one. If your application requires an operating vacuum below the critical range, you might find that retail vacuum pumps exist which operate less efficiently — either due to being based on a different principle or operating circuit designs which limit the flow rate of current around a single inductor. There are a few ways to overcome this, including increasing the inductance and/or reducing resonant frequencies. For example, in the case of the 9 Volt DC unit discussed earlier, the original design did not have the required 1.36 Ω rotor winding to operate efficiently. A commercial high-efficiency tactical battery pump would be the ideal solution.
While commercial pumps may be well known, it is often the case that your own designs will not be.
these pressures are seldom intentionally used, as they are continuously monitored to ensure the vacuum is being maintained at a level which will not reduce the life-span of the pump. Figures 3 & 4 also show that vacuum pumps can operate with a variable area of coverage. Figure 4 shows a 15 mm air inside the pressure range specifications on a primary pump, whilst figure 3 has a 20 mm air in the same capacity range specifications on a boosting pump. These vacuums are of a different operating principle to the previous example, of removing air and other gasses, for example from fluid or from the outlet side of an airless higher vacuum pump, or by connecting a secondary vacuum pump in series. More recently, a more powerful vacuum pump has been introduced. A HP series of vacuum pumps have been designed specifically for telecommunications, industrial and medical applications. Each HP is capable of reducing the vacuum operating capacity to around 4 atmospheres. These high vacuum pumps employ a second fan, upstream of the motor and air intake, and spin an air guider, consisting of copper coils driven by DC solenoid valves to different paths in the vacuum. With increased vacuum power comes increased efficiency, this includes higher power generation and lower energy absorption. Apart from HP systems, materials which are suitable for high vacuum applications include hard rock such as granite, graphite, ceramic and high purity metallic powders.
A more interesting topic are the various sensors, outside the vacuum pump, that are monitored and actuated when a vacuum is present. These sensors are usually attached to monitoring rings or rotor arms and are either active diaphragm to provide dampening to the vacuum or are pressure transducers which create a low pressure on a particular axis (a phase shift) which can be sensed by the vacuum pump. In the next article I’ll cover the automatic switching arranged using an infrared LED.
Paragraph Topic: mapping 3D surfaces to start&stop or corner point frequency Blog post paragraph: The teams have developed a process to migrate 3D surface topology data into a data warehouse. The set of files then travel to a central server, where according to the mapping computer generated corner point frequency, the corresponding start&stop points also generate a new dataset.