Audits as assessment approach

Another approach to chlorine dioxide produetion is the aeid-sodium ehlorite system. The combination of acid and sodium chlorite produces an aqueous solution of chlorine dioxide without produetion of significant amounts of free chlorine. The aeid-based proeess avoids the problem of differentiating between chlorine and chlorine dioxide for establishing an oxidant residual. This system uses liquid chemicals as the feedstoek. Each tank has a level sensor to avoid overfilling. The tanks are installed below ground in eoncrete bunkers which are capable of withstanding an explosion. There are no floor drains in these bunkers. Any spillage must be pumped with corrosion-resistant pumps. Primary and baekup sensors with alarms warn of any spillage. Because of the potential explosiveness, ehemicals are diluted prior to the produetion of ehlorine dioxide. The dilution is earried out on a bateh basis eontrolled by level monitors. Proportionate quantities of softened dilution water along with the chemieal reagents are pumped to mixing vessels by means of ealibrated double-metering pumps. After the reactor is properly filled, an agitator within the container mixes the solution. Dilutions of 9 percent HCl and 7.5 percent sodium chlorite are produced in the ehemical preparation proeess. The chlorine dioxide is subsequently manufaetured on a bateh basis. The final strength of the solution is about 20 percent, 90 percent to 95 percent of this is chlorine dioxide and 4 percent to 7 percent is chlorine.  [c.475]

Intergration process safety managment, environment, safety, health, and quality (1996) -- [ c.51 ]