{"id":31838,"date":"2025-06-27T11:25:11","date_gmt":"2025-06-27T09:25:11","guid":{"rendered":"https:\/\/www.lt-gasetechnik.de\/?p=31838"},"modified":"2025-08-07T16:43:00","modified_gmt":"2025-08-07T14:43:00","slug":"forming-gas-gas-mixer-with-sil","status":"publish","type":"post","link":"https:\/\/www.lt-gasetechnik.de\/en\/2025\/06\/27\/forming-gas-gas-mixer-with-sil\/","title":{"rendered":"Forming gas: Gas mixer with SIL"},"content":{"rendered":"
[vc_row][vc_column][vc_column_text css=””]\n

Functional safety in gas mixing systems with hydrogen-nitrogen mixtures<\/strong><\/p>\n

1. introduction<\/h3>\n

Forming gas, a mixture of hydrogen (H\u2082) and nitrogen (N\u2082), is used in numerous industrial processes – including soldering, annealing, heat treatment and metal processing. Due to the proportion of hydrogen, a highly flammable gas, there are often increased requirements for process safety. The concept of functional safety<\/strong> is becoming increasingly important, especially in safety-critical applications. <\/p>\n

The Safety Integrity Level (SIL)<\/strong> in accordance with the IEC 61508<\/strong> and IEC 61511 <\/strong>safety standards can be a benchmark for this. This article highlights the relevance of SIL in gas mixing systems for forming gas, the technical challenges and possible solutions. <\/p>\n

2. basics: What is SIL?<\/h3>\n

SIL (Safety Integrity Level) <\/strong>is a measure of the reliability of systems. https:\/\/de.wikipedia.org\/wiki\/Sicherheitsanforderungsstufe<\/a><\/p>\n

The operator determines the safety integrity level for the component or system as part of a risk assessment (HAZOP). As part of the study, potential hazards are identified and eliminated before they can lead to an accident. The study results in safety requirements at the appropriate level. There is a level classification from 1 (lowest) to 4 (highest), which represents a measure of the reliability of the system depending on the hazard potential (health, environment, plant). <\/p>\n

Specified in the IEC 61508<\/strong> (generic) and IEC 61511<\/strong> (process industry applications) standards. The probability of failure of a safety function on demand is evaluated with the aim of<\/strong> systematically reducing risks to people<\/strong>, the environment<\/strong> and technology<\/strong>. <\/p>\n[\/vc_column_text]

\"\"<\/div>[\/vc_column][\/vc_row][vc_row][vc_column][vc_column_text css=””]\n

Gas mixers for forming gas (forming gas is a gas mixture of hydrogen and nitrogen) have also been operated without SIL for more than five decades. However, the trend towards increased safety and more comprehensive risk management with a safety concept now also extends to this type of gas mixer and gas mixing systems (also known as hydrogen mixers). The safety of systems (system safety) for forming gas production can therefore be increased, for example, with a SIL 1 hydrogen gas analyzer, SIL differential pressure monitoring and a SIL 1 shutdown. This reliably monitors and prevents the impermissible accumulation of hydrogen in the process gas. <\/p>\n

3. forming gas: properties and risks<\/h3>\n

Typically, forming gas consists of 3-10 % hydrogen in nitrogen. In rare cases, gas mixtures with significantly higher hydrogen contents are also produced. The lower explosion limit (LEL) of hydrogen in air is around 4 % by volume, the upper explosion limit (UEL) is 77 % by volume. This means that hydrogen can only explode in air within a certain concentration range.<\/p>\n

Hydrogen <\/strong>has the following properties:<\/p>\n