O-A-445C
4.4.5.3 Failure criteria. Nonconformance to 3.1 shall constitute failure of this test.
4.4.6 Pyridine, naphthalene, and hydrogen sulfide determination. Unless the ammonia is made from natural gas, the following tests for pyridine, naphthalene, and hydrogen sulfide shall be made. Samples 100 ml in size shall be taken as specified in 4.4.1 instead of 500 ml samples when required.
4.4.6.1 Pyridine. About a 100-ml sample of ammonia, taken as specified in 4.4.1, shall be converted to a nitrate or a sulfate, using as little excess of acid as possible. Evaporate the solution until crystals begin to separate and transfer the concentrated solution to a separatory funnel. Make an alkaline with a saturated solution of reagent-grade sodium bicarbonate and shake with ethyl ether. The sodium bicarbonate has no action on the ammonia salt but liberates the pyridine which dissolves in the ethyl ether. Shake the solution two additional times with ethyl ether and treat the combined ether extract with distilled water and sufficient dilute nitric acid (1:3) to render it slightly acid. Evaporate the mixture to a small volume, transfer to a small distilling flask, together with a small piece of zinc to prevent bumping, and render the alkaline with sodium hydroxide solution. Distill over two thirds of the liquid into a small test tube containing 1 ml of saturated solution of reagent-grade mercuric chloride. Heat the distillate almost to boiling and filter into a small test tube. Cool to about 77 °F (25 °C). The presence of any cluster of needles shall indicate the presence of pyridine.
4.4.6.2 Naphthalene. About a 100-ml sample of ammonia, taken as specified in 4.4.1, shall be evaporated with 0.20 gram of reagent-grade picric acid. Dissolve the residue in 5 ml of boiling reagent-grade ethyl alcohol and gradually cool to about 77 °F (25 °C). Note whether any crystals have separated. Naphthalene shall be considered absent if no crystals separate out. Should crystals separate out, filter off the separated materials and recrystallize from a small amount of reagent- grade ethyl alcohol. Dry the crystals on a clay plate and determine the melting point. A melting point of 302 ± 2 °F (150° ± 1 °C) indicates the presence of naphthalene.
4.4.6.3 Hydrogen sulfide. Place a strip of lead acetate paper in a small quantity of liquid ammonia drawn from the cylinder. Any black spots on the lead acetate paper indicate the presence of hydrogen sulfide.
4.4.6.4 Failure criteria. Evidence of the presence of any pyridine, naphthalene, or hydrogen sulfide shall constitute failure of this test.
4.5 Inspection of packaging. Cylinders packed for shipment shall be examined for compliance with the requirements of section 5 of this specification.
4.6 Non-conforming product. The contractor shall withhold non-conforming products from acceptance and initiate corrective action in accordance with MIL-STD-1916.
5. PACKAGING
5.1 General requirements. No contact preservatives shall be applied to cylinders, valves, or other cylinder components.
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