Gas detector optimisation
In the event of an accidental gas release, the gas detection system is a vital tool for avoiding or reducing the consequences of a gas explosion. The objective of the gas detection study is to assess and/or improve the gas detection system with regard to preventing and mitigating gas explosions.
The complex connection between detection of gas and explosion risk is based on analysis of dispersion simulations with FLACS.
The following aspects of the gas detection system are considered:
- Gas detector layout: position, number and type of gas detectors
- Detection criteria: set point for the detectors (%LEL and LEL.m)
- Voting
- Actions associated with detection of gas: e.g. shut down ignition sources and initiate ESD
The gas detection system is assessed in two ways:
- By the effect on the explosion risk, i.e. in terms of the probability of exceedance. This requires a probabilistic explosion analysis.
- By determining the probability of and time to detection. This requires a comprehensive definition of which size gas cloud must be detected.
Based on the above, the gas detection system can be compared to the clients criteria. For example: 1) the sum effect of the detection system should reduce the 10-4 explosion pressure with 30%, 2) 95% of all "dangerous leaks" must be detected by 2 detectors within 20 seconds.
The gas detection system is improved/optimized iteratively by proposing changes and testing them, (e.g. increase number of detectors with 10, 20, ... or decrease detector set point from 30%LEL to 20%LEL, etc.).
In addition qualitative information about the detection system is reported, e.g. lack of detector density in a particular area, advice on appropriate and on ineffective actions associated with detection.
Contact
Ronan Abiven
Phone no: +47 415 04 229
Email: ronan(at)gexcon.com
