At the premises of the Environment Park, a technological hub in Torino, an atmospheric wind tunnel, SEASTAR-WT, has been designed and realised to host tests which need wind velocities up to 8 m/s. It has proven optimal for tests on an oil&gas platform mock-up (1:10) where air and natural gas releases were performed to simulate accidental events on real platforms during normal operation. The mixture adopted contained a maximum of 2.2% of methane in air, that is 50% of the Low Flammability Limit of methane: this choice was dictated by safety reasons, i.e., to avoid that a dangerous flammable atmosphere in the wind tunnel was ever possible.
The next step in the exploitation of the wind tunnel has been the shift towards the use of hydrogen in spite of methane, considering the present interest in this energy vector. This shift, however, entails some issues related to the compatibility of materials, especially those used in the gas supply line and controls (mass flow controllers, valves, pressure reducers). The whole wind tunnel environment had to be checked for suitability, including the fans which, while enhancing safety thanks to their dilution action, can be flooded by a possibly flammable cloud rich in hydrogen.
It was proven feasible to operate mixtures with low hydrogen content, e.g. 2% in air, without any significant change to the available instrumentation and equipment: all the components were already compatible with hydrogen. Sensors that are necessary for testing the dispersion of gas onto the mock-up only just needed specific calibration for the new gas.
When pure hydrogen is deployed, instead, more attention must be paid to the concentration (or dilution) that can be achieved in the wind tunnel. A preliminary HAC (Hazardous Area Classification) was performed which showed that it is still possible to keep the existing fans in presence of high H2 concentration while the central part of the test room is a Zone 1 and the equipment inside must be compliant (ignition free).
