The Question:

How much variation in measured weight is possible due to changes in =
ambient temperature?

Yes, I know the question has several ambiguous parts. Let me try to =
narrow the options.

My company uses several toploading balances in Quality Control for food =
product production. A typical balance is the A&D FX-6000. We are =
usually weighing in the range of two ounces to twenty ounces. The =
testing area has a high humidity, 80% to 100%, and the temperature can =
range from 70=B0 F. to 90=B0 F. I have frequently heard of the need to =
re-calibrate a balance to maintain accuracy when the ambient conditions =
change. What I have yet to hear is the range of measurement change =
which could be caused by a given temperature change. I realize that the =
effect of temperature on various balances will be different and that =
changes in other ambient conditions can also cause change. What I hope =
to find out is whether the possible variations could be great enough to =
adversely affect our quality control. If the possible variation in =
measurement caused by a change of 20=B0 F. on our 6000 gram, .1g =
resolution balance is .003 grams, it will be well within our allowed =
tolerance for the product; if the variation could be .3 grams it might =
cause unacceptable product variation.

Thank you for any assistance you can provide. I would be happy to =
answer any questions or attempt a more detailed discription.

John Scott, Quality Assurance
Truitt Bros., Inc.
1105 Front St. NE
Salem, OR
(503) 362-3674 ext 289
johns@truittbros.com