EPA Regulations, Water Chemistry & Toxic Chemicals
Hydrogen Explosion Investigation
A relatively new water treatment plant used an electrolytic process to generate sodium hypochlorite (NaOCl) from sodium chloride (NaCl). The strategy of using liquid sodium hypochlorite for disinfecting water instead of gaseous chlorine (CL2) is popular because the liquid is generally safer and falls under fewer OSHA and EPA standards. The further idea of generating the liquid sodium hypochlorite on an as-needed basis and in limited quantities also has certain obvious safety advantages.
One of the disadvantages of the electrolytic process is that hydrogen gas is also created as a byproduct. The hydrogen is supposed to be vented, by design, to the atmosphere before the liquid sodium hypochlorite passes into a holding tank.
For various reasons, in this instance it is believed that the hydrogen vent line was closed, thereby forcing the hydrogen gas into the liquid holding tank where it accumulated. In order to repair a leak in the tank, plant workers had drained the tank to within a few inches and then lowered an electric pump into the tank to remove the remaining liquid. When the switch was thrown to turn on the pump, the tank exploded. One worker was killed by the blast.
The main issues investigated by Chemaxx focused on the mechanisms and rates by which hydrogen gas is generated and subsequently accumulated in the holding tank. The need for active venting, warning signs and incidents of a similar nature were also reviewed.
Dr. Fox is a fire expert, explosion expert and chemical expert with extensive experience in OSHA, EPA and DOT chemical regulations and chemical safety.
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