A Primer on Precision Scale Calibration and Test Weights

Precision digital scales and analytical balances must be recalibrated for accuracy to be in compliance with international standards and to maintain good laboratory practices.  Analytical balances such as the Kern ABJ series can be recalibrated using internal motor-driven weights.  The internal calibration sequence is initiated manually.  Semi-micro analytical balances such as the Kern ABT series automatically recalibrate using internal weights under four scenarios:  1) Four hours after the previous calibration; 2) When there is a fluctuation in temperature of 0.5oC (0.9oF); 3) When the balance is switched from standby to weighing mode and condition (1) or (2) has been met or 4) If the balance was disconnected from its power source.

Other scales require external recalibration, which is performed by using test weights under procedures that should be spelled out in your company’s Quality Management manual.… Read the rest

Important Precision Scale Terminology You Need to Know

Digital scales and analytical balances play a crucial role across a broad spectrum of industries to help maintain high GLP and GMP standards in pharmaceutical labs and manufacturing, or in any industry where the need for weighing accuracy is paramount.  Written operating procedures governing accurate weighing and record keeping go a long way in supporting any organization’s goal to achieve excellence.

What I’ve found is there are discrepancies in how certain digital scale manufacturers describe the performance of their products.  Incorrect scale specifications and term definitions can lead to problems when these scales are part of precision manufacturing processes.

A case in point:  one website I checked equates readout to accuracy.  Readout is what you see on the digital display.  A long row of digits may look impressive but if the scale is not calibrated properly it most likely is not accurate. “Accuracy” as defined by weighing-systems.com is the extent … Read the rest

Improve Precision Scale Accuracy by Negating Electrostatic Charge

When using precision digital scales and analytical balances to measure in grams and milligrams it does not take much to throw off a reading.  Something seemingly as innocuous as an electrostatic charge, for example, can yield inaccurate results.  This usually occurs when non-conductive materials are being weighed – such as plastic, china and glass.  Because they can carry an electrostatic charge an electromagnetic field can be generated between the goods being weighed and the precision balance or scale. This can impact accuracy by as much as a gram.… Read the rest

How to Count on Your Digital Counting Scales

There’s no doubt that using digital counting scales can save time and money.  Easier to explain is time, because these accurate tools can do in seconds or minutes what it would take hours to count by hand.  That in itself saves time, but if the scales are also used in inventory control they can help identify unusual movement of product out of storage.  Who is taking the product and why?

As good as they are – and products such as Kern’s CXB counting scale are examples – when using them one must keep in mind the old computer admonition “garbage in, garbage out.”

These scales can weigh but they can’t think.  This requires operators to establish uniformity of weight across the products being weighed.  What can throw this off?  Well, some products in the batch may have burrs or other imperfections that will lead to inaccurate counts.  In fact, anything … Read the rest