ALMOVÉ Car 1 seamana -
As a result of this incident, Du Pont, by internal policy decision, has discontinued shipping MMAN solution in any type of container (tank car, tank truck or drums). In all present plants and in any we build in the future, including the proposed unit on Stonecutters Island in Hong Kong, MMAN solution will be produced on-site from monomethylamine and nitric acid in facilities carefully designed to minimize the possibility of explosion.
The second incident occurred on July 4, 1976, when a storage tank from which 86% MMAN solution was being pumped accidentally detonated causing extensive equipment damage, some injuries to personnel but no fatalities.
Extensive investigation following the incident conclusively showed that the explosion was caused by malfunction of the submerged centrifugal pump being used to pump the MMAN solution. Friction between rotating metal parts caused sufficient heat buildup to cause the MMAN solution in the pump to detonate.
Numerous tests run subsequent to the second incident confirm earlier results which showed MMAN to be relatively insensitive to shock and/or heat compared to other detonable materials. Therefore, it was concluded that MMAN can be produced, transferred and stored with risks no greater than analogous chemicals provided it is protected from intensive energy input.
However, it was decided that in view of the consequence of an incident, regardless of how remote its possibility, the MMAN operation should be separated from other buildings in any new plant.
In addition to providing proper separation, all existing Du Pont plants are now equipped as follows to minimize the risk of explosion with MMAN solution.
• The quantity of MMAN solution held in storage is kept to the practical minimum.
• Only air-powered, spark-free, rubber diaphragm pumps of approved design, having no metal-to-metal contact, are used for pumping MMAN solution. Pump operation is limited to low speed which subjects the solution being pumped to minimum energy input.
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