Red is the colour of danger. We know this intuitively from traffic lights and safety signage, where it means ‘prohibition’. According to the EN 1089-3, red is also the colour assigned to hydrogen gas cylinder shoulders. A red shoulder also identifies other flammable gases. But, with appropriate measures such as risk assessment, HAZOP and the implementation of appropriate mitigating actions, like gas detection, the risks associated with hydrogen production can be minimised.
Intelligent process protection
The use of gas detection must be combined with a process that asks the question: how did this leak take place and what would be a suitable reaction?. This is known as ‘a cause and effect matrix’. It is often the case that a specialist gas detection company will work together with the plant designer and operator to implement the right technology and safety control systems for the process and the gases that it contains.
Beyond the hardware design and construction, engineering expertise and operational insight are required to devise safety management systems which link the gas detection alarms with likely causes and appropriate mitigation. For some gas alarms a simple response such as closing an actuated valve may be suitable to eliminate the hazard. Or, a full emergency shut down of the process and evacuation may be required if the combination of alarms indicates an extremely hazardous situation. This is how the ‘cause and effect matrix’ adds value to the design of the safety equipment and related emergency response procedures.
Energy gases such as hydrogen and methane demand specific attention due to the danger of fire and explosion. For a leak to air, hydrogen has an LEL (lower explosive limit) of 4% and a UEL (upper explosive limit) of 75% – that is an extremely wide range. And spark ignition from electrical components or maintenance activities is an ever-present risk. The combination of these hazards adds up to a situation where the need for explosimeters and flame detection systems becomes clear.
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