Expert Insight: Weighing masterclass: A comprehensive run through of the basics of weighing

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Christian Weidner, Product Manager, Sartorius Lab Instruments

In this webinar, now available on demand, Christian Weidner, Product Manager, Sartorius Lab Instruments, provides insight into the world of weighing technology, explains the definitions for typical technical terms, and shares tips and tricks on what you need to do to achieve the best possible weighing results.

Read on for highlights of the Q&A session and register now to watch the webinar on demand.

What is the difference between tare and zero?

CW: “Zero” means that you zero the display when the weighing pan is unloaded. Zeroing a balance is only possible within a certain limit of the weighing range itself. It does not reduce the maximum capacity of the balance. “Tare” means you zero the display when the balance is loaded. An example would be to zero the display when an empty container is placed on the balance.

What is the best way to keep the balance clean after its use?

CW: The best way is by using a brush, microfiber cloth, or cotton cloth. Then, depending on the balance itself, how it is produced and what it is made of, you can also use distilled water or cleaners like ethanol.

What is the difference between the terms E and D? Sometimes they are equal, and sometimes not.

CW: D is the readability of the balance, it's the scale interval. E is the value for type-approved balances, so, the minimum weight, which you are allowed to measure on a type-approved balance. And that can be different to D.

What weighing units are available for balances?

CW: There are several weighing units available on laboratory balances. Besides gram, kilogram or milligram, there are also units like carat, pounds, or ounce available. The availability really depends on the type of the balance you are working with, and if it is a standard or type-approved balance. More important is the availability of weighing units depending on the national legal requirements at the end, so if you are allowed to weigh in certain units.

We have an analytical balance and as we try and weigh 50 mL or larger volumetric flasks the weight will drift for a long time and sometimes won’t become stable.  What is causing this and what can we do to be able to weigh these vessels?  We do utilize an anti-static brush.

CW: This might occur due to evaporation from the sample. To avoid this, we recommend making use of special vessels e.g., narrow-necked or covered vessels, stabilize the sample humidity before the weighing process, and work quickly.

What is the best way to maintain temperature balance between inside and outside the balance?

CW: The environmental conditions should always be kept as constant as possible, with no high fluctuations in e.g., temperature and humidity. After turning on the balance, and depending on the resolution of the balance, a certain warmup time must be considered before the balance can be used. To avoid a warmup period, we always recommend not disconnecting the balance from power and always leaving the balance in standby mode while it is not in use.

I am having issues with my balancing due to an unstable floor. The balance is on a good lab bench, but as a person walks by the floor will shift, causing the weight to jump around and eventually come back to a stable value. Can anything be done to help counter the shift in the floor, and make a more stable surface for the balance?

CW: The workbench should be always placed close to or next to a wall. Instead of using a standard workbench, you can also install, for example, a weighing table which is made from e.g., granite stone. These tables have absorbers to reduce environmental effects like vibrations. If this doesn't work, there is also a wall mounting table available, which could provide a solution.

For the new weights, which is the initial choice of calibration intervals?

CW: The initial choice or the initial recommendation is to calibrate every 12 months, so once a year. We recommend doing that at least three times over three years. After that time, we can also recommend expanding that period, or even to shrink that period.

What is the difference between readability and term scale interval?

CW: Both have more or less the same meaning. They describe the smallest difference in mass that can be read on the balance. It is the smallest digital step of a balance. So, there is no difference of readability or scale interval.

Want to learn more about calibration weights, selection, storage, and correct handling, watch the full webinar here>>

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