Hydrogen service: when is IIC equipment necessary, and when is IIB+H2 enough?
Hydrogen projects are multiplying. Some specifications ask for IIC everywhere, others accept IIB+H2. How do you decide, and how do flameproof joints, gland selection and gas detection change when the process gas is hydrogen?
Replies: 1
- excodex
A short note to frame the question.
Hydrogen is listed in gas group IIC, so equipment marked IIC covers it. IIB+H2 means the equipment is IIB but has also been assessed for hydrogen; it does not cover acetylene or carbon disulphide. Where hydrogen is the only IIC gas present, IIB+H2 equipment can be a valid choice, provided the temperature class and EPL also fit.
In practice, the decision is often driven by availability and cost rather than by the area classification. We would like to hear from members:
- Does your project specification simply say "IIC everywhere", or do you allow IIB+H2 where the classification permits it?
- For flameproof equipment, have you had problems with cable entries or glands that were not suitable for the hydrogen group?
- For gas detection, which sensing principle do you use for hydrogen, and where do you place sensors given how quickly it rises?
The hydrogen gas card is here for reference: https://atexmarket.com/gas/hydrogen
Excodex Editor