MIL-PRF-87930B
APPENDIX B
B.2.1.4 Reagents and equipment. The following shall apply as test conditions of B.2.1:
B.2.1.4.1 Reagents.
a. Purified water free of interfering substances; the water is considered free of interfering
substances if a 100 mL sample used to dissolve 0.1 g of silver nitrate shows no turbidity after standing in
the dark for 24 hours. The purified water as described in this paragraph shall be used throughout the
procedure.
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b. Standard sodium chloride (NaCl) solution, 1 mL = 1.00 mg Cl ; weigh 1.648 g of dry NaCl
into a 1 liter (L) volumetric flask. Dilute to the mark with purified water. Transfer the thoroughly mixed
solution to a clean polyethylene bottle for storage. A 1000 mg/L (ppm) chloride standard may be
commercially obtained; must be certified.
c. 1N H2SO4; prepare by pouring 29 mL of ACS reagent grade concentrated H2SO4 into 300 mL
of purified water contained in a 1000 mL volumetric flask. Cool the solution to room temperature, dilute to
the mark with the purified water, and mix thoroughly. Transfer the solution to a plastic bottle.
d. 1N NaOH; prepare by dissolving 40 g of ACS reagent grade, low carbonate, NaOH in 300 mL
of purified water contained in a 1000 mL volumetric flask. Cool the solution to room temperature, dilute to
the mark with the purified water, and mix thoroughly. Transfer the solution to a plastic bottle and protect
from prolonged exposure to the atmosphere.
e. Bromocresol green indicator; 1% aqueous solution. Use purified water.
B.2.1.4.2 Equipment.
a. Chloride electrode solid state Orion 9417BN, or equivalent.
b. Reference electrode Orion 900200 Sure-Flow® double junction with 1M potassium nitrate
(KNO3) outer compartment filling solution, or equivalent.
c.
pH/millivolt meter, Orion 420A+ or equivalent.
B.2.2 Colorimetric method.
B.2.2.1 Procedure. Add to the propellant residue container in one vessel from 4.3.7 five
milliliters of ferric alum indicator and transfer to a 100 mL volumetric flask. Rinse the vessel with three
5 mL purified water aliquots and combine into the volumetric. Set samples aside.
Prepare a calibration blank and at a minimum two standards to bracket the expected chloride
concentration in the samples in 100 mL volumetric flasks, and add 5 mL of ferric alum indicator. Add
2.5 mL of mercuric thiocyanate solution to each volumetric, samples and standards, and dilute to the
mark with purified water. Mix the solutions thoroughly and allow to stand in darkness for 15 30 min.
Analyze in a UV-Vis spectrophotometer at 460nm, at the wavelength recommended by the instrument
manufacturer, or at that which provides the highest sensitivity using 5 cm cells. Use the blank to set the
instrument to zero absorbance and determine the absorbances of standards and samples. Prepare a
calibration curve of absorbance versus concentration and determine the chloride concentration in the
samples. The calibration correlation coefficient shall be ≥ 0.999.
B.2.2.2 Calculation. Calculate the chloride content of the propellant using the formula in B.2.1.3.
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