Testing Your Laboratory Balance (Page 3 of 6) in pdf

Testing Your Laboratory Balance Page 3

Reproducibility Testing

Reproducibility testing entails repeatedly weighing a given object, recording the results, and

analyzing those results. Select a test weight equal to, or nearly equal to, the weighing capacity

of the instrument. Utilize the chart titled "Reproducibility Test Chart."

1. Tare the instrument to read all zeros.

2. Place the test weight on the pan.

Record the reading in the column labeled "FULL SCALE" .

3. Remove the weight (DON'T REZERO), and record the reading under "ZERO"

4. Repeat steps 2 and 3 until lines 1 through 11 are all filled in.

5. Transcribe the two columns of numbers into a spreadsheet program.

6. Use the program to calculate the standard deviation of both columns of numbers.

(consult the program documentation, or "HELP" system for the spreadsheet)

7. Calculated standard deviations larger than allowed in the instrument specifications

indicate that the instrument is either operating in an unstable environment (static, air draft,

warm-up, vibration, etc.), or that the instrument is in need of repair.

Reproducibility Test Chart

Line

Zero

Full Scale

Standard Deviation (SD)

Instrument Model ________________

Instrument Serial Number__________

Date ___________________________

Person _________________________

IES Corporation

Repair of Laboratory Balances

(800) 541-0852

www

Testing Your Laboratory Balance Page 3