Combustible gas explosions can also be incredibly hazardous and, in addition to putting the lives of crew in danger, may destroy cargo and equipment as well as damaging the vessel itself.
Regular tests using gas detection equipment are intended to protect crew and vessels from unknown hazards onboard. Tests are typically used to check and maintain safe levels of oxygen in enclosed spaces, monitor levels of oxygen in inert gas and inside tanks, measure the flammability of hydrocarbon gas, measure levels of hydrocarbon gas prior to entering pump rooms and other enclosed spaces and to locate and measure other potentially toxic gases within a ship.
This HSE Safety Alert highlights the risk of misleading gas detection readings associated with the use of sampling tubes with pumped gas detectors. Sampling tubes are sometimes used to extend the reach of the detection device and/or to allow detection at an increased distance from the user.
In a recent incident a gas detector failed to detect the presence of a flammable vapour. Hot work proceeded in the belief that there was no flammable vapour present. The subsequent explosion resulted in a fatal injury.
This incident has highlighted the importance of selecting the correct systems for gas detection and verifying the effectiveness of the detection system.
The only way to know whether an instrument is capable of proper performance is to expose it to test gas. Exposing the instrument to known concentration test gas verifies that gas is properly able to reach and be detected by the sensors. It verifies the proper performance of the instrument’s alarms, and (if the instrument is equipped with a real-time display), that the readings are accurate.
This bump test guide details what a bump test is and how it should be carried out prior to using gas detection equipment to ensure the accuracy of the equipment and therefore its ability to keep the user safe.