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Topic: Weighing Device Calibration Question
Replies: 7   Last Post: Jun 25, 2012 3:05 AM

 Messages: [ Previous | Next ]
 James Waldby Posts: 237 Registered: 1/27/11
Re: Weighing Device Calibration Question
Posted: Jun 23, 2012 6:09 PM

On Sat, 23 Jun 2012 11:44:36 -0500, biofilm wrote:
> "Wally W." wrote ...
>> On Sat, 23 Jun 2012 16:07:43 +0100, Frederick Williams wrote:
>>>"Wally W." wrote:
>>>> On Fri, 22 Jun 2012 21:31:04 -0700 (PDT), John Morriss wrote:
>>>> >Are you planning to input the local value of g, or just ignore the
>>>> >approx 0.5% variation?

>>>>
>>>> Wouldn't 'g' cancel in the equations, as for a pivoting balance scale?

>>>
>>>No!

>>
>> Why not?
>>
>> The sensors have a spring rate.
>>
>> The deflection depends on the mass of the test weight and the local
>> gravity. The dial on the scale will be turned to agree with the stated
>> mass for the test weight, regardless of local gravity.

>
> on cannot read the dial to less than a 0.5% variation anyway.

David T. Ashley's original post refers to "force transducers" and
doesn't say whether the numbers are read via an indicating
dial (for which your comment could conceivably be true) or get
digitized electronically, as seems more probable. Typical
digital scales read out to one part in 5000 or better, rather
more accurately than the one part in 200 that is 0.5%. Eg, \$18
ebay #220927204058 Digital Mailing Kitchen Weighing Scales 5 kg x
1 g. / 11 lb. X 0.1 oz, at <http://www.ebay.com/itm/220927204058>
and \$7 ebay #370574576300 Digital Pocket Precise Weighing Scales
650 Grams X 0.1g at <http://www.ebay.com/itm/370574576300>.

--
jiw

Date Subject Author
6/23/12 James Waldby
6/23/12 Wally W.
6/24/12 David Bernier
6/24/12 Wally W.
6/25/12 Tim Little
6/24/12 Scott Berg
6/24/12 Wally W.