Explosion on a hydrogen production unit

The incident involved an hydrogen-on-demand unit (HOD), which was installed inside an environmental test chamber used for reliability tests. An employee was troubleshooting the chamber, assessing the HOD unit. The chamber had been reported inoperative. Two units were being tested on a work bench, both were connected by an exhaust hose to the HOD. The gas had not been properly exhausted and began to back up into the hose that was attached to the HOD. The employee removed the side panel on the chamber and it exploded while he were standing in front of it. He was killed by the explosion.

The INITIATING CAUSE was the unexpected and undetected presence of hydrogen in the testing chamber when it was open to air.
The conclusion of the OHSA legal investigation was that " the exhaust system was not designed, constructed, installed, tested and maintained properly to provide safety to life from fires and explosions. ".
Therefore, the ROOT CAUSE was an inadequate design of the installation and of the related risk assessment, lack of operative and maintenance procedures, lack of proper safety measures.

hydrogen on demand unit, testing chamber

The thermal chamber was reported inoperative that morning and was being troubleshooted.

DESCRIPTION OF THE FACILITY
The company was specialised in testing component reliability, and the thermal chamber involved in the explosion was testing energy components used in hybrid vehicles. The role of hydrogen is not disclosed. The OHSA reports mention release of potassium hydroxide, which is the main component of the electrolyte of an alkaline water electrolyser. This was probably the hydrogen production technology of the hydrogen-on-demand unit.

The explosion injured twelve employees at the time of the blast, three police officers, and two firefighter/paramedics, who were first on the scene after the explosion.
The employees and first responders suffered smoke inhalation and exposure to chemical irritants — possibly potassium hydroxide, which is a skin and respiratory irritant.
OHSA fined the company with 26,100 US$

The OHSA found the following sever law violations:
• Failure to Ventilate Hydrogen Adequately
• Lack of control of hazardous energy
• Failure to Classify an Electric/Vapor area dangerous
• Failure to Use Proper Equipment in Dangerous Electric/Vapor area
• Failure to Develop MSD Sheet for Hydrogen

The OHSA investigation found that the employer failed to provide employees and a place of employment free from recognized hazards (explosion hazards when the employer failed to ventilate hydrogen gas adequately).
The following conditions increased the potential for an explosion:
(1) Hydrogen was being created by hydrogen-on-demand (HOD) units being tested and the exhaust system was not designed, constructed, installed, tested and maintained properly to provide safety to life from fires and explosions.
(2) Procedures were not developed, documented and utilized for the control of potentially hazardous energy when employees were engaged in activities with the environmental test chamber. The exhaust hoses used to exhaust the hydrogen gas created on the test bench were connected to an exhaust hose on the HOD inside the test chamber. The air conditioning section of the chamber contains open wire heating elements.
(3) Areas designated as hazardous (classified) locations were not properly documented.
(4) The equipment was not approved for the class of location and for the ignitable or combustible properties of the specific gas that would be present.
(5) The employer did not develop a material safety data sheet for the hydrogen generated by the electrolysis process