4.5 Hydrogen sensing

As a colourless, odourless and tasteless gas, hydrogen cannot be detected by human senses, therefore, means should be provided to detect the presence of hydrogen in locations where leaks and/or accumulations may occur. When using hydrogen in confined spaces, the employment of a hydrogen detection system for early detection of leaks is essential to facilitate the activation of alarms, safety operations and where necessary, the safe evacuation of people. There are numerous hydrogen sensors/detectors commercially available operating on various principles. When installing a hydrogen gas detection system, the following questions need to be considered:

• Which is the most suitable sensing technology?
• What are the appropriate alarm thresholds for the hydrogen detection system?
• How many sensors are required?
• Where should the sensors/detectors be located?

Consulting relevant standards, regulations and guidelines can assist in the choice and correct use of a particular type(s) of hydrogen detection system most suitable for an application. Technical standards for flammable gas detectors have existed for many years, although not specifically for hydrogen. The most useful among the technical standards are the IEC 61779 series of standards [48], although they do not specifically focus on hydrogen, however, the development of a standard specific to the performance and testing of hydrogen detection apparatus is underway (ISO Technical Committee 197 - WG13). Further information on regulations, codes and standards relating to flammable gases and hydrogen is published in Chapter 6 of the HySafe BRHS [49], some useful regulations codes and standards are also shown in Appendix A2.


Detection techniques, sensor positioning, alarm levels, sensor maintenance and calibration can be seen at Appendix A7.