Other matters may be noted when selecting BDV tester
(1) Sample temperature measurement
An instrument that features built-in automatic oil-sample temperature measurement offers important benefits. With these instruments, the temperature sensor is in contact with a thin section of the test cell; unlike a conventional thermometer, the sensor does not come into direct contact with the sample, and the risk of contamination is eliminated. Also the user is less likely to be tempted to save time by not waiting for the sample to cool before testing. Finally, there is no fragile thermometer to break.
(2) Test voltage verification
Checking between calibration dates. Test results are only as accurate as the instrument's ability to measure and control its output voltage, so it is good practice to verify the operation of the instrument between calibrations. This is not because instruments are likely to lose accuracy, but because if something occurs that affects calibration and it isn't noticed, it could mean that a lot of inconvenient and potentially expensive retesting is needed.
Voltage check meters. Many manufacturers offer a voltage check meter that can be fitted to the instrument in place of the measuring vessel. This allows the user to compare the voltage shown on the check meter with that shown on the instrument display. Check meters are not sufficiently accurate to use as a calibration standard, but they provide a very good way of detecting changes in instrument calibration. Users should record the check meter readings each time a voltage check is carried out, so that changes can be easily identified. If any significant change is detected, the instrument should not be used until it has been returned to the manufacturer for servicing and recalibration.
(3) Changes to test standards
When choosing a test instrument, it is essential to be sure that it can handle future changes to test standards and the introduction of new test standards. It should be possible to eaily load new test sequences into the instrument to reflect these changes. It is worth checking that the instrument supports custom test sequences that can be programmed by the user.
