First Name
Andy
Last Name
Piatt
Severity
Incident
Was Hydrogen Released?
Yes
Was There Ignition?
Yes
Incident Date
Jun 28, 2008
Setting
Equipment
  • Safety Systems
  • Measurement / Sensing Device
  • Piping/Fittings/Valves
  • Piping
  • Ventilation System
  • Venting System
  • Laboratory Equipment
  • Gas Chromatograph
Damage and Injuries
Contributing Factors
When Incident Was Discovered
Lessons Learned

It is important to understand the requirements and standards associated with safe equipment design (especially electrical equipment containing an internal ignition source with flammable gas) in potentially explosive atmosphere environments. Misinterpretation of requirements and standards can lead to serious consequences. If the application of a standard is not fully understood, it is advisable to contact the author of the standard to remove any misunderstanding and not try to interpret the rules.
Gas detection instrument location is critical to proper functioning. Light gases like hydrogen rise in air, and gas detection needs to be at the high point in the potential source area so that even small leaks can be detected. Various alarm/action thresholds below the lower flammability limit (LFL) of the flammable gas give additional warning of a possible problem in the event of a gas leak. The following is a summary of how equipment involved in this incident should have been installed.
The gas chromatograph should not be installed in a sealed cabinet, but should follow explosive atmosphere design standards to have forced ventilation with a minimum flow rate of 12 times the cabinet volume per hour and to exhaust outside the building. With this change, the analysis room can remain in its current configuration and it does not fall under the explosive atmosphere regulations.
The fixed gas detector must be installed in the cabinet sealed volume, and must comply with explosive atmosphere regulations. The gas detector must be connected to an interlock system and set with two threshold levels; the first at 25% of the LFL (which sends an alarm) and the second at 50% of the LFL (which closes the hydrogen isolation safety valve). For this gas detector, the 100% LFL threshold level is set at 4% hydrogen in air.
To minimize the consequences of a possible leak of hydrogen inside the cabinet, it is recommended that the hydrogen isolation safety valve be installed outside the analysis room.
The explosive atmosphere regulations also require the installation of a door switch that stops the supply of electricity and flammable gases whenever the door is opened (for example, when performing maintenance). This door switch limits the risk of creating an explosive atmosphere in the room that is not regulated under explosive atmosphere standards.

Key:

  • = No Ignition
  • = Explosion
  • = Fire
Hydrogen Incident Summaries by Equipment and Primary Cause/Issue
Equipment / Cause Equipment Design or Selection Component Failure Operational Error Installation or Maintenance Inadequate Gas or Flame Detection Emergency Shutdown Response Other or Unknown
Hydrogen Gas Metal Cylinder or Regulator   3/31/2012
4/30/1995
2/6/2013
4/26/2010 12/31/1969     3/17/1999
11/1/2001
12/23/2003
Piping/Valves 4/4/2002
2/2/2008
5/11/1999
4/20/1987
11/4/1997
12/31/1969
8/19/1986
7/27/1991
12/19/2004
2/6/2008
10/3/2008
4/5/2006
5/1/2007
9/19/2007
10/31/1980
2/7/2009 1/24/1999
2/24/2006
6/8/1998
12/31/1969
2/7/2009

9/1/1992
10/31/1980

10/3/2008  
Tubing/Fittings/Hose   9/23/1999
8/2/2004
8/6/2008
9/19/2007
1/1/1982 9/30/2004
10/7/2005
  10/7/2005  
Compressor   10/5/2009
6/10/2007
8/21/2008
1/15/2019
    10/5/2009 8/21/2008  
Liquid Hydrogen Tank or Delivery Truck 4/27/1989 12/19/2004
1/19/2009
8/6/2004 12/31/1969   1/1/1974 12/17/2004
Pressure Relief Device 7/25/2013
5/4/2012
1/15/2002
1/08/2007
12/31/1969        
Instrument 1/15/2019 3/17/1999
12/31/1969
2/6/2013
    11/13/73    
Hydrogen Generation Equipment 7/27/1999     10/23/2001      
Vehicle or Lift Truck   7/21/2011         2/8/2011
12/9/2010
Fuel Dispenser   8/2/2004
5/1/2007
6/11/2007
9/19/2007
  2/24/2006
1/22/2009
     
Fuel Cell Stack            

5/3/2004
12/9/2010
2/8/2011

Hydrogen Cooled Generator       12/31/1969
2/7/2009
     
Other (floor drain, lab
anaerobic chamber,
heated glassware,
test chamber,
gaseous hydrogen
composite cylinder,
delivery truck)
  11/14/1994
7/21/2011
7/27/1999
6/28/2010
8/21/2008
12/31/1969
3/22/2018
    6/10/2019
  • = No Ignition
  • = Explosion
  • = Fire