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INSPECTO Automation AG, Switzerland / Sniffers for 5 Gallon bottles,Visual Inspection, PET  Recycling Inspection

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The technology of sniffers (an overview)
Mass Spectrometer Spectrum analysis Operation of a MS       < Klick for mor Information

Methods for the inspection Return (Rewash) Bottles

The main problem of checking bottles for foreign substances with a Sniffer is the production speed of up to 45 thousand bottles per hour (12.5 bottles/sec.). This is why many of the analytical methods common in chemistry (chromatography) can not be used. Some basic technologies have been developed to match the necessary speed and sensitivity. These can be divided into different categories:

  • Pulse Fluorescence: "Activated" by electromagnetic radiation such as UV light molecules transmit energy to other specific spectra (wavelengths). => Detection of gasoline, diesel, naphthalene, Exxon.

  • Spectroscopic Procedures (with "light"): UV / VIS (visible light) / IR (infrared) . The spectrum permits conclusions concerning structure and composition. Most of time absobtion spectras with Gas-specific filters.

  • Microwaves for Ammonia compounds IR (SOX) => alcohols, volatile hydrocarbon, acetone, toluene.

  • Photo ionisation: Ionization with UV => (PID). Measurement of conductivity of ionized gas. Wide-range detection of chemical compounds, but unsuitable for soft drinks and alcoholic drinks because of missing selectivity.

  • Chemo Luminescence: Stimulation of molecules by "oxidation" => Detection of Ammoniac and similar compounds and aliphatic hydrocarbons. (KR)

  • Mass Spectroscopy: Analysis of the gas composition by "measuring" the mass of molecules and its concentration. => A universal widely used, reliable procedure. Analysis of mass spectra, wide-band detection and identification of all unwanted, known and unknown substances with a specific gaseous phase.

  • Residual Liquid Color Measurement: Complementing the Sniffer, this process measures the “colour” of the residual liquid within the visible light spectrum. => Detection of foreign substances with no specific gas phase and detection of perfumed substances ("PEX" detergents) by measuring the foam produced after the injection of carbonate or soda (NAOH).

  • Electronic nose Chips with semiconductors or thick films with chemical substances having reactions to certain gases. Several sensors with different characteristics form a nose, able of distinguishing odours. Unsuitable for alcoholics or soft drinks because of missing selectivity. Relatively slow.
  • Chemical Sensors in combination with Leak measurment is very successful. Developed and protected by Inspecto Automation used in Canis.

How good are the Sniffers? The sensitivity of the sensors for solvents, hydrocarbons and ammonia is usually around 0.1 up to 1 micro litre per litre of air.(1 ml = 1 Qube-mm).

All these methods have one thing in common: The Sniffer takes a sample out of the gaseous phase from each bottle. Just imagine what it would mean for a human nose to have to smell 36'000 bottles! It is clear therefore that Sniffers cannot be maintenance-free. With each gas sample some dirt and some sugar will be sucked in, polluting the pipes and sensors in the course of time. However, this problem has been largely solved by means of an automatic cleaning device and change parts.

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