Bicarbonate hazard

Another property related to the sodium hazard of irrigation waters is the bicarbonate concentration. Bicarbonate toxicides associated with some waters generally arise from deficiencies of iron or other micronutrients caused by the resultant high pH. Precipitation of calcium carbonate from such waters, 

Early workers used the residual sodium carbonate (RSC) to predict the tendency of calcium carbonate to precipitate from high-bicarbonate waters and thus create a sodium hazard. The RSC was defined as 

FIGURE 11.4. Influences of adjusted SAR of the Irrigation water upon the SAR of saturation extracts from Pakistani soils after three years of cropping. (From R. S. Ayers and D. W. Westcot. 1976. Water Quality for Agriculture. Food and Agriculture Organization of the UN, Rome.) 

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Methanol does not pose an undue toxicity hazard if handled in weU-ventilated areas, and is rated as a slight health hazard by the National Fire Protection Association (NFPA). The TLV is 200 ppm with a STEL of 250 ppm, and the limit which is immediately dangerous to Hfe and health is 25,000 ppm. Accidental ingestion is immediately treated by inducing vomiting, followed by adrninistration of sodium bicarbonate. Rinsing with water is effective in treating external exposure. 

Chemical Reactivity - Reactivity with Water Reacts slowly to generate hydrogen chloride (hydrochloric acid). The reaction is not hazardous Reactivity with Common Materials Corrodes metal slowly Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water, rinse with sodium bicarbonate or lime solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Spill/Leak Disposal Isolate the incident scene dress in proper personal protective equipment (see above) do not allow contact with any materials, liquid or gas stop and/or control leak or hazard if possible to do so and control water - use water spray to control vapor and any vapor cloud. Contain product and keep phosgene from entering sewers, streams, or water intakes. Dike surface flow, and depending on the temperature, try to neutralize the product for disposal using agricultural lime (slaked lime), crushed limestone, or soda ash, or sodium bicarbonate. 

Multipurpose dry chemical extinguishers (20-A 80B-C) should be provided in warehouses and shop buildings where wood, paper, plastics, and other flammable solids, as well as flammable liquids, may be stored. In grease manufacturing and compounding or similar operations where little or no wood, paper, and similar combustibles are stored, but where flammable liquids may be prevalent, potassium bicarbonate dry chemical extinguishers should be used. Extinguishers should be located not more than 75 ft (23 m) away from any potential Class A fire hazard and not more than 50 ft (15 m) from Class B fire hazards. 

Steam-generating plants, air compressor plants, and similar plants should be provided with potassium bicarbonate dry chemical extinguishers (120-B C) for Class B or Class C fires in the areas containing hydrocarbons or other flammable liquids. For fires in electrical equipment, at least one extinguisher (10-B C) should be provided. If Class Afire hazards exist, multipurpose dry chemical extinguishers (20-A 80-B C) or water extinguishers should be provided. 

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