Safety Alert: CEMHD 1 2017 Siemens – Maxum II Edition Gas Chromatograph – Safety Features (link)
This Safety Alert is aimed at those using the Siemens Maxum II Edition Gas Chromatograph product which is believed to be widely in use in the Oil, Gas and Chemicals industries. The purpose of the Gas Chromatograph (GC) is to analyse samples of chemicals and determine the composition. Units can be installed both on industrial plant and lab facilities. Samples are fed into the Gas Chromatograph using carrier gases including hydrogen and nitrogen.
The unit is ATEX certified for use in potentially hazardous areas. The protection concept for the upper Electronics Enclosure is “PX”. This design is based on a purge flow of air being used to dilute any flammable gases present below the flammable limits.
The issue was discovered after an incident when an instrument technician was injured as a result of an explosion. The GC was being returned to service after being left in ‘hold’ status’, during this ‘hold’ period flammable gas (hydrogen) had accumulated in the electronics enclosure of the GC. The main safety feature to prevent the potential build-up of gas, an automatic purge unit, was not re-engaged as part of the start-up operation. It is possible to by-pass the automatic purge unit prior to start up by setting the GC mode from ‘operation’ to ‘maintenance’ using a key located behind the detector cabinet panel.
The injuries sustained were life changing and could have been even more serious.
Although the incident occurred whilst operating the Siemens Maxum II GC unit there is the possibility that a similar set of circumstances may be replicated with GC equipment from other manufacturers.
Source: HSE.