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Siemens - Maxum II Edition Gas Chromatograph - Safety Features

Health and Safety Executive - Safety Alert
Department Name: Chemicals, Explosives and Microbiological Hazards Division
Bulletin No: CEMHD 1 2017
Issue Date: 1st October 2017
Target Audience:

Users of Gas Chromatograph equipment typically used for the analysis of chemical composition in the following sectors:

  • Oil and gas
  • Chemical processing and production
Key Issues:

This Safety Alert highlights the need for tight control procedures when using the Siemens Maxum II Edition Gas Chromatograph. Specifically when resuming operations following a period in the maintenance mode.


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.

Maxum 2 Chromatograph

Action required

The actions required are in line with duties required by health and safety law and in particular the Dangerous Substances and Explosive Atmospheres Regulations (2002) Regulation 6 and the Provision and Use of Work Equipment Regulations (1998) Regulation 12.

Users of Siemens Maxum Edition II GC’s should review the operation of the units, specifically the automatic purge unit control, making specific reference to the latest version of the Maxum maintenance manual edition: “PD Maxum II Maintenance Manual 10/2015 2000596-001”.

Users of Siemens Maxum Edition II GC’s should discuss the suitability of their current operating arrangements for the GC’s with Siemens.

Users of GC’s produced by other manufacturers should discuss the suitability of their current operating arrangements for the GC’s with the manufacturers.

Relevant legal documents

The relevant legal requirements are:

  1. The Provision and Use of Work Equipment Regulations 1998 (PUWER)
  2. Dangerous Substances and Explosive Atmospheres Regulations 2002

General note

Please pass this information to a colleague who may have this Product/ Equipment or operate this type of system/process.

The designers, manufacturers and suppliers of this equipment are reminded of their duties set out by Section 6 of the Health and Safety at Work Act 1974.


Please refer to the manual delivered with your device and the latest release of the safety note. If your manual is missing, please contact Siemens support.

Siemens, “Maxum Edition II - Maintenance Manual Edition 8/2007 2000596-001,” 2007

Siemens, “PD Maxum II Maintenance Manual 10/2015 2000596-001”

Siemens, “Maxum II PD PA AP Explosion Protection Safety Standards Manual. November 2016. A5E02220442001 Rev 3”

Further information

Any queries relating to this safety alert should be addressed to:

Health and Safety Executive
Process Safety Unit
Building 5 North, Floor 2
Redgrave Court
Merton Road
L20 7HS

Siemens UK product support at:

Phone Number : 0845 850 7600

This alert sheet contains notes on good practice which are not compulsory but which you may find helpful in considering what you need to do.