Spectrophotomètre Brewer MKIII

• Haute précision des longeurs dóndes

• Gamme de longueurs dóndes adaptée

• Excellente réduction de la lumière parasite

• Stabilité supérieure à long terme

 

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Spectrophotomètre Brewer MKIII

Le spectrophotomètre BREWER est composé d’un spectrophotomètre inaltérable, d’un pointeur azimut et d’un support. Il surveille quasi simultanément la colonne d’ozone totale, le SO2 et les spectres UV.

Le pointage à deux axes, les sélections adaptées des filtres, la calibration à bord des longueurs d’ondes et l’enregistrement des données sont gérés via un système électronique interne et un ordinateur central compatible IBM. Le logiciel de contrôle du PC permet une programmation sur 24h et un fonctionnement à distance sans surveillance.  

Le rayonnement ultraviolet (UV) est lié au cancer de la peau, au vieillissement de la peau, à la cataracte et à la suppression du système immunitaire chez les humains et les animaux. Chez les plantes, une exposition accrue au rayonnement UV endommage les cultures et réduit les rendements.

Du point de vue de l’évaluation des risques, une exposition aux rayons UV représente un risque potentiellement élevé. Bien qu’une surveillance des UV soit nécessaire, la nature du rayonnement et notre sensibilité à celui-ci représentent un défi en matière de collecte de données. Si ce défi n’était pas relevé, notre compréhension des futures tendances et influences des UV pourrait rester aléatoire.  

Cela se confirme en particulier si on se réfère aux études réalisées sur les ultraviolets nocifs. A moins que le spectre des UV solaires soit bien connu, il est difficile d’établir un rapport entre l’intensité des UVA/ UVB et les réponses biologiques. Pour garantir la fiabilité d’une mesure du rayonnement UV du spectre solaire, l’instrumentation doit être dotée de qualités spécifiques. Le spectrophotomètre BREWER illustre ces qualités et contribue à la compréhension du rayonnement UV solaire et de son impact actuel et futur sur la biosphère.

Brewer Mk III recommandé par Environnement Canada

Environnement Canada (EC) recommande le spectrophotomètre d’ozone « Mark III Brewer », qui est bien plus performant que les Brewer Mk II et Mk IV, afin de mesurer le rayonnement solaire et l’ozone dans la région ultraviolette (UV) du spectre. Ce choix s’impose car la lumière parasite du système optique à double monochromateur utilisé dans le Mk III est considérablement réduite par rapport au monochromateur simple du Mk II et du Mk IV.

C’est la raison pour laquelle Kipp & Zonen ne fabrique plus les modèles Mk II et Mk IV et produit uniquement le Brewer Mk III depuis un certain nombre d’années. Cependant, les pièces de rechange, le service après-vente et le retour usine sont toujours disponibles pour tous les modèles de Brewer.

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Specifications

Measurement method Dual spectrometer with PMT detector
Résolution 0.6 nm
Gamme spectrale 286.5 nm to 363 nm
Stabilité des longueurs d'ondes 0.01 nm (au dessus de la température de service)
Power supply 230 VAC or 115 VAC
Gamme de température -20 ºC to +50 ºC
Gamme de température -50 ºC to +50 (avec option couverture isotherme) ºC
Total column measurement Ozone and Sulphur Dioxide
UV measurement Spectral, plus UVA, UVB, UVE, UVI

FAQ

  • How often should my Brewer be calibrated?
    • For the Brewer spectrophotometer, regular recalibration is necessary for the reliability of the Brewer’s Ozone measurements. The World Meteorological Organisation (WMO) recommends that each Brewer is calibrated at least once every two years. The Brewer is a stable instrument and drifts in the instruments can be monitored and corrected because of the diagnostic tests such as Standard Lamp and Dead Time measurements.

      Some Brewer users prefer to have their Brewers calibrated every year. By doing this, they assure their Brewer data is of the highest quality. Drifts in the instrument are corrected sooner and the regular check with a reference Brewer increases the reliability of the data.

      If you would like to discuss calibration of your Brewer at the factory or at your location please contact us.

      Is your question still unanswered? Contact Support
  • The Brewer software says “LAMP NOT ON, HG TEST TERMINATED”. Should I replace the lamp?
    • The Brewer software will give this error message when it tries to make a HG measurement but cannot see the light of the Mercury lamp. There are several causes why the Brewer could give this error message. One of the motors could be in an incorrect position, so that the Brewer does not see the light. The PMT could not be measuring correctly or the lamp could need replacement.

      The first step in troubleshooting is doing a full reset (RE command) in the Brewer software. Then try to perform the HG test again.

      If the HG test still returns the error message one should find out if this also occurs for tests with the standard lamp. Type SL<enter> in the Brewer software.

      If Both the HG test and the SL test fail, then either a motor is not moving correctly or there is a problem with the PMT/photon counting circuitry. Use the maintenance manual for further troubleshooting.

      If the SL works but the HG fails, then there might be a problem with your lamp. For single board Brewers: Type AP to get the voltage of the Mercury Lamp (HG lamp). The voltage should be around 10 V. If the Voltage is off by 2 Volts, one should inspect the lamp.

      The HG or mercury lamp is the lowest lamp in the lamp housing. Usually, if the lamp needs replacement, the glass will have black spots or the filament will be broken.

      If the lamp needs to be replaced, do not touch the quartz envelope with your hands. Use a tissue or a piece of cloth. The lamp should be tightened firmly. Also, from the top, both filaments should be visible.

      Is your question still unanswered? Contact Support
  • How does the Brewer compensate Ozone measurements for temperature?
    • The Brewer instrument is capable of operating in different conditions from the tropics to the Antarctic. As the Brewer is used outside the whole year round, its Ozone measurements should not have any temperature dependency.

      During the factory testing of the Brewer it undergoes a test in the temperature chamber from 0°C to +45 °C. Standard Lamp measurements are taken throughout this entire temperature range. This is a simulated Ozone measurement based on the halogen lamp inside the Brewer. Although the intensity of the lamp does change with temperature, the wavelength shift is negligible.

      After the temperature test, the data of the SL measurements is analysed. During the analysis, the temperature correction coefficients are created. These coefficients compensate for the change in spectral response of the Brewer at the Ozone wavelengths. With the coefficients installed in the Brewer software, the Ozone measurements will not be affected by the temperature of the instrument.

      Is your question still unanswered? Contact Support
  • When and how should I clean the Brewer’s azimuth tracker drive?
    • The Brewer azimuth tracker has a driving mechanism based on friction between the drive shaft and the drive plate. These items will get dirty over time and the azimuth tracker is likely to slip. This can be noticed by a tracker discrepancy after AZ or SR tests.

      The drive mechanism can be cleaned by using a clean lint-free cloth with alcohol or with “garage” soap (soap with grains of sand in it). Switch the tracker power off! Remove the rear tracker cover (the cover on the side opposite to the power switch). Use the cloth with alcohol or soap to rub the dirt off the drive plate and the drive shaft. Rotate the tracker to clean the entire drive plate. Be careful not to break the wire of the safety switch. After cleaning the entire drive plate and shaft, rub them once more with a dry piece of clean lint-free cloth to remove any remaining residue of soap/alcohol.

      When this is done, rotate the tracker to aim the Brewer approximately at the sun . Put the tracker cover back on and switch on the tracker power. Now the Brewer needs to perform some tracker resets. In the Brewer software, type “PD AZ SR 10” to perform these resets. Watch the data to check that the tracker resets without discrepancies and then put the Brewer software back into its normal schedule.

      Is your question still unanswered? Contact Support

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