Thermo Scientific 42i Instruction Manual page 251

Determining Permeation
Rate by Weight Loss
Determining Release Rate
by Transfer Standard
Thermo Fisher Scientific
Use the following procedure to determine the permeation rate by weight
loss.
1. Make sure the oven has been calibrated as described in the "Permeation
Tube Oven Calibration" procedure described previously.
2. Insert the permeation tube carefully. Do not touch with fingers.
3. Turn on the instrument.
4. Wait 24-48 hours for the permeation tube to stabilize.
5. Carefully remove the permeation tube from the oven and weigh to an
accuracy of 0.1mg. Perform this measurement as quickly as possible.
6. Replace the permeation tube into the oven of the instrument.
7. Repeat Steps 5 and 6 after two weeks.
8. Compute the weight loss of the permeation tube from the values
determined in Steps 5 through 7.
9. Repeat Steps 5 through 8 until the weight loss has been determined to a
precision of 1-2%.
10. For the most accurate work, use the permeation tube in the same oven
that was used to determine the weight loss of permeation tube.
Use the following procedure to determine the release rate by transfer
standard.
1. Make sure the oven has been calibrated as described in the
Tube Oven Calibration" procedure described previously. Also make
sure that the Transfer Standard has been properly calibrated.
2. Determine the permeation rate for the permeation tube in the Transfer
Standard, or install a certified permeation tube.
Optional Equipment
Internal Permeation Span Source
"Permeation
Model 42i Instruction Manual 9-9