MIL-STD-1330D(SH) APPENDIX D
20 September 1996
D.9.3 Prepare an IR calibration curve as follows:
D.9.3.1 Obtain an IR single beam spectrum of HCFC-225s in the clean dry 10
mm Quartz IR cell. Obtain a spectrum from 4000 cm-1
(22.22 micrometer). Save this spectrum.
(2.5 micrometer) to 450 cm-1
D.9.3.2 Drain and clean the quartz cell. Mix the fluid in Standard B vigorously for 30 seconds and then check that the fluid meniscus is at the fill line of the flask. If the fluid is not at the fill line, add HCFC-225s to bring the fluid meniscus to the fill line. Fill the quartz cell with Standard B and immediately stopper the cell. Obtain a single beam IR spectrum of Standard B from
4000 cm-1
to 450 cm-1.
D.9.3.3 Using the spectrum obtained in D.9.3.1 as the reference spectrum, generate an absorbance spectrum of Standard B. An expanded scale from 0.00 to
0.03 ODU may be necessary for the lower concentration standards. Use the
absorbance values at 2890 cm-1
(3.46 micrometer) and 2829 cm-1
(3.53 micrometer) to
construct a baseline by doing a linear regression on these two points. Calculate
and record a baseline absorbance value at 2860 cm-1
(3.50 micrometers). Subtract
this value from the peak absorbance at 2860 cm-1
record this net absorbance.
obtained from Standard B and
D.9.3.4 Repeat steps D.9.3.2 and D.9.3.3 for Standards C and D.
D.9.3.5 From the net absorbance values obtained for Standards B, C, and D in steps D.9.3.3 and D.9.3.4, and the known concentrations from D.9.2.3 calculate an equation relating absorbance and concentration using linear regression. The correlation coefficient should be 0.95 or higher.
D.10 Procedure.
D.10.1 Obtain an IR single beam spectrum of HCFC-225s in the clean dry 10-mm
quartz IR cell. Obtain a spectrum from 4000 cm-1
(2.5 micrometer) to 450 cm-1
(22.22 micrometer). Save this spectrum. Perform this step daily when in use.
D.10.2 Mix the sample by shaking the sample bottle. Remove the cap carefully to release any pressure build-up.
NOTE 5: The IR cell should be thoroughly cleaned with fresh solvent and then dried prior to measuring each sample. Do not insert the cell stopper so tightly that the solvent cannot expand during IR measurement which could cause the cell to burst.
D.10.3 Obtain an IR single beam spectrum of the HCFC-225s sample in the same clean dry 10-mm quartz IR cell used to develop the calibration curve.
D.10.4 Using the spectrum obtained in D.10.1 as the reference spectrum, generate an absorbance spectrum of the sample. An expanded scale from 0.00 to
0.03 ODU may be necessary for the lower concentration standards. Use the
absorbance values at 2890 cm-1
(3.46 micrometer) and 2829 cm-1
(3.53 micrometer) to
construct a baseline by doing a linear regression on these two points. Calculate
and record a baseline absorbance value at 2860 cm-1
(3.50 micrometers). Subtract
this value from the peak absorbance at 2860 cm-1
record this net absorbance.
D.11 Calculation.
obtained from the sample and
D.11.1 Determine the concentration in mg/L of oil and grease in the solvent using the equation developed in D.9.3.
D.11.2 For HCFC-225s used as a final cleaner (such as gauge cleaning), convert mg/L to ppm by dividing mg/L by 1.55 (the specific density of HCFC-225s), and record as hydrocarbon oil and grease.
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