A Test Method for Assessing the Performance of Oil Mist Detectors
Ignition of flammable mists, particularly oil mist, which can occur in offshore locations such as gas turbine enclosures, diesel/ships engine rooms and platform legs present a significant major accident hazard potential. Oil mist detection with appropriate emergency response (OMDs) is identified as a significant risk mitigation. However, there are gaps in the knowledge as to how effectively, locate, maintain and operate OMDs in different environments. This work aims to produce a test method capable of assessing the effectiveness of oil mist detection under conditions typical of those found in practice to enable these gaps to be addressed.
A method for testing OMDs has been produced based on methods previously developed at HSL and a recent international standard. The use of isokinetic gravimetric samplers is recommended to measure absolute airborne spray/mist concentration with which to compare OMD response. It is a fundamental method and not affected by changes in the physical properties of the droplets, taking around 1–10 minutes to carry out the measurement.
The test method will allow the performance of all types of OMD to be fully characterised as a function of mist concentration, mist droplet size, mist composition, and air velocity. It will also allow the effects of interfering aerosols such as dust and water droplets to be investigated. The effect of detector ageing on detection efficacy can also be established.
This report and the work it describes were funded by the Health and Safety Executive. Its contents, including any opinions and/or conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy.