On Electronic Scales: Weighing the Balance
Posted by: Peter Rillero in All Grade Levels, Classroom Best Practices, Elementary School Science, High School Science, Middle School Science, biology, chemistry, lab apparatus, physics, science education, tags: balances, electronic scales, equipment, scienceThe electronic Ohaus scales that I ordered a few years ago are slowly dying. Only half the digits are readable on the numeric displays or in some cases there are no readable numbers. At NSTA in Phoenix, I stopped by the Ohaus booth and the representative was not surprised when I told her this. Unfortunately, she informed me, the scales have only a one-year warranty. From the initial lot we bought, half are unusable.
Using the scales in our science methods classes at Arizona State University, shouldn’t be taxing compared to ordinary high school, middle school, or elementary school use. So it surprised me that the LD50 (a biology term for half a population dying) was achieved so quickly. But maybe my expectations are out of line, our Honda Odyssey, my wife informed me today, has 170,000 miles on it. But a one-year warrant, really? That makes me wonder how confident the manufacturer is in their product.
I like how fast the electronic balances gave readings. No longer were drafts, fast walkers, or table shakers an issue in our classroom, as compared to the old reliable triple beam balance scales. I predicted the end to triple beam balances at the high school and an even quicker death to the elementary level pan balances. But, perhaps I was too hasty.
I am not sure if Ohaus scales are worse then others. The sales rep informed me that in the newer models, the problem has been addressed with the displays. That won’t benefit me; I will put my next order in with a different company. But she also told me of another issue that seems likely to affect most scales that are not top end. Adding too much weight can permanently damage the weighing device. Yikes! It seems like a common occurrence, especially when doing full inquiry experiences, that students would add too much weight. Indeed, it seems like there should be warning signs on the scales about maximum loads.And this brings up a final issue. Why is it that we can’t find good reviews of science apparatus? I have bought things that are great and things that are lousy; wouldn’t it be nice to have a place like CNET that helps us tell what is good and what is not. But if you have scale advice, please do leave a comment.
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Hello I just had to comment on the statement concerning adding too much weight in your posting. While it is true that most balances of this type rely on a rather weak component to actually accomplish the weighing that component is usually protected pretty well. Usually, especially with Ohaus balances, the load cell is protected to at least 150% of rated load. This will not of course help if the balances are abused and heavy loads are continually dropped on the weighing platform.
Thank you Tom. It seems like scales should have a warning label to not exceed a certain weight that is put right on the scale.
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Electronic scales can be purchased through any science supply company. Although, I just recently found a great deal at the store called Harbor Freight.