Syngas explosion at a university laboratory

A university lab was investigating the production of hydrogen and methane from biomass made of wooden chips or sawdust. The experimental furnace was a concrete cylindrical furnace of the diameter of 4 m and the height of 5 m. A fire jet occurred together with the explosion, and sparks fell on the professor in charge and students nearby. Nine persons were slightly injured.
According to the fire station and the police, gas ignition was attempted at the gas outlet of the experimental apparatus, to check the effective generation of the gas. However, the gas did not ignite at first. it is probable that it formed first an falammable cloud and then ignited withdelay, causing an explosion.
(translation from Japanese by means of Google Translate)

The INITIATING CAUSE was a hazardous action of the research team, which ignited the gaseous products of the biomass gasification process to ascertain the successful generation of synthesis gas (syngas).
The ROOT CAUSE could be attributed to the failure of performing a proper risk assessment and of providing the safety measures required to guarantee minimal level of safety, by the manager in charge.

The experimental device was being tested.

Nine persons were burned in face and hands and feet, and carried to the hospital by ambulances. They were only slightly injured.

There are various safe methods to ascertain the composition of flammable gases, which avoid the need to ignite the whole flow. These methods range from using gas detectors and analysers, up to sampling the gases and testing their energy content under controlled conditions.