UV Stability Kit and Precision Power Supply

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UV Stability Kit and Precision Power Supply

Regular use of the stability kit is recommended to check that the UV response is stable. This is very important to correctly report UVA, UVB and UVE irradiances in W/m2 and UV Index values. The kit is not required for Ozone and Sulphur Dioxide measurements, which are ratiometric in nature.

The UV Stability Kit is a source of irradiance to routinely check the stability of the spectral response of a Brewer spectrophotometer. The kit replicates the factory UV calibration method, but at a lower level of accuracy and is not a calibration standard. Ideally, it should be powered from a separate AC outlet, rather than the Brewer accessory power output cable.

A foam-lined aluminium carry case contains a baffled calibrator housing fitted with a 200 W quartz halogen lamp mounted in a special adapter for accurate optical alignment. Two additional lamps in adapters are provided. All the lamps are pre-aged, and have individual identification numbers.

A spacer assembly with light curtain ensures that the calibration lamp is at the correct distance from the Brewer input optics. A bench-type power supply with keyboard and display provides very stable DC voltage and current to the lamp with programmable ramp time and cooling time.

It is important to mention that this UV Stability Kit has much superior characteristics to the earlier model with handheld meter, which is no longer available.

This is achieved by using a more massive lamp housing with built-in ventilation to keep the temperature inside the lamp housing stable during the measurement process, higher quality and more powerful lamp, precision optical alignment, and a far better power supply.

These improvements allow the Brewer UV measurement stability to be checked within ± 2 % of the factory calibration that uses traceable 1000 W calibration lamps.

The UV Stability Kit is portable and can be easy assembled and ready to operate in a few minutes. It can be used indoors or outdoors (in dry condition with little wind).

The UV Stability Kit and Precision Power Supply can be used with all models of Brewer; MkII, MkIII and MkIV, except for a few early examples that were not fitted with the dome and diffuser for global UV radiation measurements.  

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Specifications

Measurement method Spectral irradiance
Lamp Quartz halogen (accurately aligned on special adapter)
Lamp power (constant current) 200 W / 6.3A
Lamp wavelength range 250 to 2500 nm
Number of lamps on adapters supplied 3
Power supply 88 to 264 VAC (47 to 63 Hz)
Power supply output current: 0.1 to 6.4 ADC
Power supply output voltage: 0 to 48 VDC
Power supply control: supply control

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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