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Analytical vs Digital

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ChemoSabe:
jamiroquai wrote...

Digital scales are too easily ruined by carrying them around like a pack of cigs in the pocket as is easily to space-off and do. Whereas the twin-beams which do go to the 1/100th of a gram come with that nice hand dish and you can
  pre-set the desired weight and tend to the given weights & measures at hand.

In my own eperience this statement is 100% true. Started out with a triple beam. Johnny law stole it. Got a small digital, it worked for about 3 months and then it got weird on me (inaccurate) Then happily procured the same model of triple beam that I started with and have stuck with it ever since.

biotechdude:
As an undergrad, my chem professor told me that as a rule of thumb, drop the last decimal point from digital scales (as its worthless)

Meaning, if your scales are 100g +/- 0.1g then it should only be used for measuring whole grams.  Further, if measuring points; get a digi that goes to .01 or .001.  Even then, the build quality will determine how quickly it looses accuracy.  Moreso, carrying it round in a pocket will quickly fuck it up - they are precision instruments after all.

The beams are great for accuratly pre-weighing retail bags etc.  But a bit impractical whilst wheeling and dealing (jewellery of course..).  It is important to have a set procedure for weighing and minimise external factors such as wind and ensure the surface on which you weigh is hard and flat.  You can end up unknowingly ripping off the buyer or yourself.  Also, it is wise to carry caliberation weights to handle any disputes if they arise.

Freemind148:
Digital scales rely on accuracy of electronic components.  the load-cell itself is rather stable and reliable.  However, the electronic circuits that process the load-cell's output may or may not be.  electronic components such as resistors, capacitors and oscillators may change value, leak and drift over time (aging) and are affected by temperature.  If the manufacturers use cheap components and have design that does not have any temperature compensation, there scales won't be all that robust nor reliable.

Most of the digital scales would reuire warm up time (15 minutes) to allow all the components to reach operating temperature etc.  It is then best to do calibration with standard weight.  It would be preferable to have two standard weight near the upper end and another one near the low end since this allow you to check it's linearity.  Unfortuntely digital scale typically comes with one standard weight in the middle of its range; therefore, you may have to buy one or two more if you are serious and critical about the accuracy of the entire range.  If the results show see-saw behavior i.e good at one end of the range but not the other, then the balance is no longer good.

I agree that if you are really picky about the accuracy, nothing beat mecahical scale that is based on beam-balance.

Tdurden969:
Swim loves his Sartorius lp2200s digital analytical balance.

2.2kg max with .01g readabillity

Course you can't carry it in your pocket.

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