Advice for Acculab 123 Scale Users

Some of our forum members have observed issues with the Acculab VIC-123, an 0.001g precision electronic balance made by Sartorius. The two main complaints seem to be sensitivity to drafts, and instability of zero, causing weight read-outs to “drift” over time. We have seen the latter problem in less expensive scales such as the PACT. (Read PACT report).

Forum member Ronemus, who lists his profession as “instrumentation scientist”, offers the following advice:

“It is necessary to isolate the scale from drafts and vibrations. Laboratory scales with this sort of resolution (.001g) generally have a housing around the pan with sliding doors for access and vibration isolators in the feet. Those scales cost thousands of dollars, and some features must be cut to reach a price we’re willing to pay. Unfortunately, the instruction manuals accompanying our scales generally aren’t very good at spelling out the steps necessary to have then operate to our satisfaction.

A small draft (one you can barely feel) can easily shift the reading a few tenths of a grain, so some sort of enclosure is needed. I use a cardboard file box with one end cut out, so 3 sides and the top remain, and that’s good enough for 0.1 gr (6 mg) stability; however, that may not be sufficient for 0.01 gr.

For stable zeros it’s necessary to warm up for at least a few hours (they’re generally left on continuously to avoid drift) and keep the room temperature fairly constant (within a few degrees).

Inexpensive scales are also susceptible to electrical noise, either riding the power line or through the air. Power line noise can be eliminated with a good filtered power strip (I recommend a Tripp-Lite Iso-Bar), not just a surge suppressor. Cordless and cell phones, fluorescent lights, wireless computer networks, baby monitors, etc. can cause problems at short range, so they should be kept away from the scale as much as possible.”