How are automatic burettes used in accordance with the Pellet pattern?
Attach rubber bellows on automatic burette in according to Pellet pattern, squeeze rubber bellows for filling, wait for automatic zeroing, and titrate by opening the stopcock. Please be informed that automatic burettes with intermediate stopcocks allow the return of unused solution after solution.
How can the meniscus be read easily?
In case no Schellbach stripe is imprinted the volume of a concave meniscus has to be read at the lowest point of the liquid level. Here the lowest point of the meniscus has to touch the upper edge of the graduation mark. For parallax-free adjustment of the meniscus, the burette is held upright and the observer's eye must be at the same height as the meniscus. In this position the ring mark will appear as a line. The meniscus will appear darker and more easily readable in front of a light background if a piece of dark paper is held behind the instrument immediately beneath the ring or graduation mark.
What should be done if air bubbles persist in the burette?
Hold burette at an angle and lightly tap a finger against the location of the bubble. In case the air bubbles could not be eliminated with this procedure, drain standard solution completely and repeat filling procedure.
Is it necessary to lubricate stopcocks?
PTFE valve spindles operate smoothly without any lubrication. Glass keys should be lubricated very slight to operate smoothly.
What does "Error limit according to class B, DIN EN ISO 385" mean?
Some burettes contain subdivision marks or a kind of glass which are not prescribed in DIN EN ISO 385. Subsequently these burettes do not meet all specifications of the standard, but they meet the error limits according to class B of DIN EN ISO 385.
How are automatic burettes used following the modular concept?
Attach rubber bellows on glass bottle of modular automatic burette, squeeze rubber bellows for filling, wait for automatic zeroing, and titrate by opening the stopcock.
What kind of screening inks does BRAND use for printing the burets?
Blue and white enamel are printed on the outer surface and provide a high contrast and an optimal combination of chemical resistance and legibility for BLAUBRAND (cl. A) and SILBERBRAND (cl. B) burets.
Are burettes calibrated according to 'TC, In' or 'TD, Ex'?
'TD, Ex': The delivered quantity of liquid corresponds exactly to the capacity indicated on the instrument.
What is the difference between class A and AS?
Class A and AS refer always to highest quality grade in accord to the respective standards and 'S' stands for swift delivery only used for volumetric instruments calibrated to deliver, pipettes and burettes (TD, Ex). For volumetric instruments calibrated to contain (TC, In) a swift delivery is not necessary and therefore not defined in the respective standards.