Hydrogen cyanide

CAS RN: 74-90-8

Storage Conditions

Keep cylinders of hydrogen cyanide (HCN) cool and away from open flames. Make certain that HCN cylinders are adequately supported and grounded during storage and emptying. Store cylinders in a vertical position. Do not drop cylinders or damage them by impact. Cylinders must be returned to the supplier within 90 days of the filling date marked on the cylinders, regardless of whether or not the contents have been used. This is due to the possibility of HCN becoming unstable over time. If there is any indication that the HCN is becoming unstable, such as a darkening of the product or an increase in cylinder pressure, contact the supplier immediately for instructions.
Fireproof. Separated from food and feedstuffs. Cool. Store only if stabilized.
Store in a cool, dry, well-ventilated location. Shelf life should not exceed 90 days or as otherwise specified by manufacturer.
Handling, storage, and transportation of hydrogen cyanide are determined by its low boiling point, high toxicity, and instability in the presence of moisture, bases, or other impurities. The liquid acid is relatively uncorrosive. Materials compatible with HCN at normal temperatures are stainless steel, Hastelloy, and Monel. To prevent polymerization, stabilizing agents, such as sulfuric acid, phosphoric acid, oxalic or acetic acid, and sulfur dioxide are used. The type and quantity of stabilizer (usually <0.5%) depend on storage capacity, temperature, and residence time in a container. A combination of H2SO4 and SO2 prevents the decomposition of HCN in the liquid and vapor phases. Larger quantities of hydrogen cyanide are stored at a maximum temperature of 5 deg C and must be permanently recirculated. Additionally, the color of the liquid is monitored and should not exceed APHA 20. To keep the concentration of gas below the danger level, good ventilation of buildings in which HCN is stored and handled is of primary importance.
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