Ignited hydrogen leak at an aerospace testing facility

The event occurred in a university research building dedicated to the study of the take-off of space launchers. During the hydrogen pressure pre-setting phase, a flame developed at a pressure regulator on the line located on the walkway above the test hall.

Operators gave the alarm, based on video surveillance images. They closed the supply line and started to purge the system.

The INITIATING CAUSE was a combination of two technical failures:
- A hydrogen leak on the pressure regulator (technical cause unknown).
- An electrical short circuit on one of the equipment in the environment near the regulator.
The latter was caused either by a material defective of a system temporarily installed on the bridge for experimentation, either by over-voltage due to accumulation of moisture in one of the elements of the electrical circuit following a water leak the day before.

The ROOT CAUSE is unknown.

experimental testing laboratory, pressure reducer device

The event occurred during the starting of a test, in the hydrogen pressure pre-setting phase

No injury and damage.

The alarm was given by an operator. On-site officers contained the fire.

Probably better procedures for adequate monitoring/control of materials and equipment will reduce probability of occurrence of this type of incident.

According to the ARIA report, the operator is implementing the following measures to be able to restart the testing campaign:
1. Replacement of the electrical connection potentially causing the short circuit, as well as electrical cables damaged by the fire;
2. Displacement of the system potentially causing the short circuit, in an area far from the hydrogen line;
3. Partial restart of the control-command console, aiming at leak tests and verification of the absence of short circuit;
4. Replacement of the valves, seals of the defective hydrogen pressure regulator and check of the other pressure regulators and pressure sensors;
5. Leak-test of the line, first under nitrogen and then under hydrogen;
6. Re-powering of the entire control panel for functional tests of the combustion chamber, first at low flow rates of hydrogen, then at nominal flow rate.