INCIDENT TITLE: Fume off on Spent Acid (DNA) filter and Drain Line

A trail batch of nitration was in progress in building A1. All the interlocks were checked before starting the process. The vacuum was checked with water in the acid and alkali filters and found to be to requirement. The acid filter and alkali filter water drained into a labyrinth. Water in the nitrator drains into a drowning tank. Approximately 50 liters of nitric acid drained to the nitrator from the concentrated nitric acid (CAN) measuring tank. After stirring, acid drains to acid filter. The acid filter drains to the fume off tank.