Ionization tube
An ionization tube is an essential part of an air ionizer for ionizing the ambient air and forming free oxygen radicals with the aim of air conditioning. The ionization tube consists of a cylindrical insulator in the form of a thin, non-conductive glass bulb closed on one side, in the cavity of which a sleeve-shaped metallic inner electrode leans and which is enclosed on the outside by a sleeve-shaped metallic outer electrode. When high voltage between 1.5 kV and 2.85 kV is applied, corona discharges occur , which emit diffuse electron emission into the air and lead to the formation of free oxygen radicals in the form of small clusters due to the ionic bond . This released electrical energy, in the form of a cold plasma, generates free oxygen radicals that are positively and negatively charged and then group into grapes, so-called oxygen clusters. Due to their high oxidation potential, these free oxygen radicals cause air disinfection and can be transported by central ventilation systems to the relevant area in the building or, with free convection , distributed directly in the room. The air treatment, such. B. disinfection , odor neutralization or pollutant degradation , in the sense of bioclimatics , improves the room air, breaks down volatile organic compounds (VOC) and, among other things, counteracts the sick building syndrome .
There are numerous external and internal control and regulation systems for ionization devices with ionization tubes that are operated with an operating voltage of 1.5–2.85 kV on the ionization tube. Depending on the type of ionization tube, a very low power of 1 to 7 W is required. The transition from an ionization tube to an ozone-forming ionization tube , typically operating voltages above 3 kV, is fluid and is only determined by the level of the operating voltage on the tube itself. Modern sensor and measurement technology offers a high degree of security and traceability.
history
The first ozone tube was developed by Werner von Siemens in 1857 and was used for pure ozone generation in order to ensure the drinking water quality in cities on a large-scale, and thus to avoid diseases caused by contaminated drinking water. The supposedly first ionization tube also came from Werner von Siemens and was, however, an electron tube that was used as a vacuum measuring tube in measurement technology .
The first isolator tube, which was developed as an ionization tube for generating corona discharges in air, goes back to a question raised by Albert Einstein . As early as 1908 he asked himself and his friends from the “ Akademie Olympia ” study group the question of the properties of good air . In 1910 he had the well-known potential multiplier built by his friend Paul Habicht and spent many years researching this device with Conrad Habicht . Numerous research results were then implemented industrially.
Paul Habicht's son, Conrad John Habicht, developed the isolator tube known today at the ETH Zurich from 1943–1954 and defined the special features with regard to the “bioclimatic” of air. He founded his sole proprietorship "Reinlufttechnik CJ hawk", which for the first time ionizing units produced with the ionisation and with the aim of disinfection of air, the odor minimization in buildings, rooms and ventilation systems , the preservation of food in cold stores and improved indoor air quality marketed. C. John Habicht was also the one who had the ionization performance of approx. 1.8 million ions on an ionization tube officially determined by the Swiss Office for Materials Testing for the first time . Numerous other research reports prove this design and the max. Ionization performance at 2,850 volts AC voltage without ozone formation as well.
construction
The classic structure of an insulator tube, in the form of an ionization tube, consisted of a very thin-walled glass bulb, closed on one side, mostly made of rock crystal or borosilicate glass , in which a perforated metallic electrode was located. The applied high voltage comes from the transformer via a threaded pin in the one-sided end cap of the glass bulb and an inner stud bolt with a contact spring rim to the inner perforated plate , which served as an electrode. The coronary arteries on the insulator tube that arise when a silent electrical discharge occurs , glow slightly green. The glass bulb and end cap are permanently glued together. After curing, the bond results in a sealing lip that prevents moisture, grease and dirt from penetrating. This closed and sealed design minimizes the internal oxidation of all built-in parts and enables long-lasting and short-circuit-free continuous operation, even in high humidity . Conventional ionization tubes lost their ionization power after 10,000 hours of operation, because the inner electrode was made of pure aluminum and was physically dissolved as a sacrificial anode . Even the insulator tubes filled with noble gas did not significantly extend the continuous operating power. Newer designs today simply use high-quality composite materials , stainless steel and special industrial glass .
development
The main reason for failure of an ionization tube is the glass breakage of the thin insulating glass bulb, which leads to an electrical short circuit even with small hairline cracks . Impurities in the glass are very rare, but can also lead to a punctual breakdown . Conventional quartz glass used as insulating glass ages in its structure, which has been replaced by modern industrial glass as a result of further developments in the glass industry. These industrial glasses now have very special electrical properties, as required in pipeline construction in the chemical and pharmaceutical industries . The electrical conductivity of these glass tubes corresponds to <10 −8 S / m , whereby the specific resistance is from 1 · 10 16 to 10 21 Ω · mm 2 / m . At the same time, aging, UV resistance, yellowing , impact resistance, hairline cracks and the risk of electrical breakdown are safely avoided by these modern series glasses.
In today's ionization tubes , instead of a pure aluminum perforated plate, a composite metal made of stainless steel and aluminum with a thickness of 0.2 millimeters is increasingly being used as the inner electrode , thus reducing the service life of the ionization tube to a safe 24,000 to max. 48,000 operating hours extended. Some manufacturers use instead of a perforated sheet made of composite metal z. B. bristle contacts, expanded metal , spiral wire, metal springs or a silver coating, applied to the inner wall of the glass bulb, as an inner electrode.
The outer electrode around the glass bulb, in the form of a sleeve, initially consisted of a rigid wire mat that was spot-welded as a sharp-edged seam along the length . In the course of time this was replaced by a durable, insensitive, soft stainless steel knitted fabric that is maintenance-free. Dirt deposits, grease and silicate formation in the wire mesh can be easily washed out during maintenance work. The outer cathode can still be used even after the insulator has failed. The later disposal of all metal parts can be done normally via the metal trade.
Today's ionization tubes are made of materials that meet the requirements of the UL94 armature class ( IEC / DIN EN 60695-11-10 and 60695-11-20 ), the strict UL standard (USA) and can be installed with IP54 protection . The materials used inside, made of aluminum, composite metals and stainless steel, are also standard parts and comply with the DIN standard .
The end cap on the isolator piston is an injection molded part made of glass fiber reinforced polypropylene PP with dimensionally stable and fire-reducing properties. The connecting threaded pin in the end cap is a stainless steel turned part or a stamped part according to DIN standards, which can be fitted in any shape and dimension. These connecting pins vary depending on the manufacturer and are dependent on the type of ionizing unit that goes with it. All threaded pins are largely maintenance-free.
Areas of application
Ionization devices with ionization tubes and a working voltage of <2.85 kV alternating voltage are mostly used in the ventilation technology of buildings, rooms and ventilation systems for disinfection, improvement of air quality, odor neutralization and the reduction of pollutants , which can be determined with test tubes . The classic ionization devices, with the combination of high-voltage transformer and ionization tube, form only a very small amount of ozone below a MAK value of <0.01 ppm , measurable with an ionometer , and are unproblematic to use.
Ionization tube types
Each ionization tube defines its power output via the materials used in it and via the outer surface of the corona on the insulator bulb in the area of the outer electrode. Different lengths are defined under different type designations. Another aspect is the diameter of the isolator piston and its minimum wall thickness. A third aspect is the different threaded pins in the end cap of the ionization tube, which can be M5 or M6 depending on the manufacturer .
Ionization tubes with only one end cap and a glass bulb closed on one side have an anode connection and require a loose cathode clamp. Ionization bipole tubes with two end caps on a piece of glass tube are stored on both sides and have both an anode connection and a cathode connection.
Various manufacturers offer ionization devices with ionization tubes that often appear to be visually identical, but the coronary power output (ionization energy eV) of an ionization tube is always linked to the high-voltage transformer used by the respective manufacturer. The input voltages at the transformer vary from 12 to 24 volts direct voltage and 120 to 230 volts alternating voltage or direct voltage and are quite unproblematic for transformer manufacturers when producing the respective transformer. The optimal ionization performance of an ionization tube is only determined by the quality of the materials used.
Compact ionization units and smaller ionization modules are available for various input voltages; these range from 12 to 24 volts direct voltage in the motor vehicle to over 120 to 230 volts alternating voltage in the network and can be equipped with various sizes of ionization tubes. Continuous operation using a car battery or solar module is just as possible as it can be used in country-specific mains voltages .
Compare to similar tubes
Ionization tubes that are operated with 3–4 kV AC or DC voltage generate ozone , similar to a UV-C / UV-V tube with <185 nm , which therefore has an indirect, germicidal and pollutant-reducing effect. At operating voltages of 4 to 7 kV, the discharge on the ionization tube is maximized, but afterwards an insulator tube becomes an ozone tube. The voltage, type and the ionization power output ultimately define the power spectrum.
Insulating tubes of any type are subject to world no standardization , specification and should have a label for type approval wear.
lifespan
The service life of the ionization tube essentially depends on the handling or transport of the entire ionization tube and in particular the glass bulb before it is actually installed, since hairline cracks or dirt deposits can occur. Humidity, fat deposits and dirt deposits on the ionization tube often cause unwanted leakage currents into the ionization device and destroy the ionization technology. There is also a short circuit in the high-voltage transformer and destroy it. These leakage currents leave visible traces of fire (like lightning) on the end cap of the ionization tube, on the ionization device or in the transformer. During continuous electrical operation, vibrations affect the ionization tube due to air flow, as does the careful handling of the ionization tube during maintenance by the service staff. These external influences on the ionization system can already be reduced in advance through professional planning, manufacture, transport and the optimal installation situation and later reduced through regular, proper maintenance by competent persons.
Norms
DIN EN 61010 Safety regulations for electrical measuring, control, regulating and laboratory devices
- Part 1: General requirements - (IEC 61010-1: 2010 + Cor.:2011); German version EN 61010-1: 2010
literature
- József Illy: The practical Einstein: experiments, patents, inventions. Johns Hopkins University Press, 2012, ISBN 978-1-4214-0457-8
- Amjad Al-Musaed: Biophilic and Bioclimatic Architecture. Springer London, 2010, ISBN 978-1-84996-533-0
- Thomas Franz Schneider: Albert Einstein - Conrad Habicht: Documents of a childhood friendship: correspondence, separate prints and other materials. TF Schneider, Basel 2000.
- Wolfgang Roeske: Drinking water disinfection. 2nd edition, Oldenbourg-Industrieverlag, 2007, ISBN 3-8356-3119-5 .
- Werner von Siemens: Memoirs. edited by Wilfried Feldenkirchen. Piper, 2008, ISBN 978-3-492-05269-6 , p. 181.
- Felix Gad Sulman: Health, weather and climate. S. Karger 1976, ISBN 978-3-8055-2350-9 .
- Minna Kempe: Jonisering av inomhusluft.En interesting air ventilation technique with många frågetecken . In: Serie R: Reports . No. 5 , 2012, ISBN 978-952-5839-45-6 , ISSN 1799-4179 (Finnish, online [PDF; 1.9 MB ] Finnish research report on indoor air ionization).
- John Jukes, Andrew Jenkins and Julian Laws: The Impact of Improved Air Quality on Productivity and Health in the Workplace . 2006 ( online [PDF; 58 kB ]).
Web links
Individual evidence
- ↑ Ionized air in the interior. (PDF file, 1.4 MB) Lucerne University of Applied Sciences and Arts - edition 01/2013 , accessed on June 5, 2013
- ^ Scientific publications from the Siemens works, Volume 19, page 279, J. Springer, 1940, University of Michigan Wolfgang Roeske: Drinking water disinfection. 2nd edition, Oldenbourg-Industrieverlag, 2007, ISBN 3-8356-3119-5 , p. 9.
- ^ Conrad Habicht, Paul Habicht: Electrostatic potential multiplier according to A. Einstein . In: Physikalische Zeitschrift . tape 11 , 1910, pp. 532-535 . , see also University Museum Tübingen on the electrostatic potential multiplier
- ↑ Patent specification USA - Bipolar ionization tube: US2010 / 0247389 A1
- ↑ Patent specification USA - BI-POLAR IONIZATION TUBE BASE AND TUBE SOCKET : US2012 / 0154973
- ↑ Patent Europe - ionisation : EP 1394477 B1
- ↑ European patent specification - discharge tube : EP 1611053 A2 - WO2004091061A2
- ↑ Wyrsch O. (1979): EMPA, Investigation Reports No. 15'1743-AC