What are the key technical specifications and quality indicators for industrial calcium nitrite?

What are the key technical specifications and quality indicators for industrial calcium nitrite?
Industrial calcium nitrite, with the formula Ca(NO2)2 and molecular weight 132.1, is typically a white to pale yellow powder or hexagonal crystal. The relevant Chinese standard is GB 28656-2012, which specifies limits for calcium nitrite content, calcium nitrate impurity, moisture, and water-insoluble matter. Production usually involves absorbing equal volumes of NO and NO2 into lime slurry, where the stoichiometric balance is critical. If NO is in excess, absorption is incomplete and toxic gas is emitted; if NO2 is in excess, the product becomes contaminated with calcium nitrate, lowering the nitrite assay. For buyers, verifying the nitrite-to-nitrate ratio is essential because nitrate impurities reduce corrosion-inhibiting efficiency in concrete and can affect setting behavior. Moisture control is also important, as the salt is deliquescent and tends to absorb atmospheric water, leading to caking and weight inconsistencies. Quality-conscious buyers should request certificates of analysis and test samples before bulk orders.