Severity
Incident
Leak
Yes
Ignition
No

Incorrect Flammable Gas Cylinder Attached to Anaerobic Chamber

A laboratory research technician entered a lab to begin preparing samples that were to ultimately be purged in an anaerobic chamber (glove box) located in that room. As the technician walked into the lab, she looked at the chamber to see if it was adequately inflated. This chamber is equipped with a gas concentration meter, capable of simultaneously displaying the oxygen and hydrogen concentrations of the chamber atmosphere. Under normal operating conditions, the atmosphere inside the chamber is comprised of 0% oxygen (as intended/desired for an anaerobic atmosphere), approximately 2-3% hydrogen, and with the remaining balance being nitrogen (approximately 98-97%). Under such normal operating conditions, the hydrogen concentration inside the chamber is less than the lower explosive limit (LEL) of hydrogen to prevent an explosion in case air or oxygen were ever inadvertently introduced into the chamber. When the technician observed the meter's digital readouts, the oxygen concentration in the chamber was still 0% but the hydrogen concentration was at 43%. (The explosive range of hydrogen in air is 4% to 75%) An alarm light was also flashing on the meter, but an audible alarm was not heard. (At first, the technician turned the meter off and back on again believing something was wrong with the meter. She then checked the placarding of the compressed gas cylinders that were hooked up to the chamber manifold system and discovered that one of the cylinders was a mixture of 95% hydrogen and 5% nitrogen, instead of the 5% hydrogen and 95% nitrogen cylinder that was supposed to be there and immediately summoned assistance. The face of the manifold onto which the erroneous cylinder was connected is labeled as "5% H2/95% N2". The cylinder was last changed out 30 days prior to the incident, by the facility's maintenance personnel. And equipment user log indicates that the chamber had been used a couple of times since the cylinder change-out. In addition to the manifold labeling, there are also job aid instructions posted in the work area pertaining to the operation of the chamber by the laboratory researchers.

Evidence is present to show that the research staff actually requested a mixture 5% H2 and 95% N2 through the onsite acquisition system, but the vendor failed to supply the customer with the requested mixture; instead, a mixture of 95% H2 and 5% N2 was supplied. The investigation team determined that a mixture of 95% H2 and 5% N2 would have never been in the facility (for maintenance staff and end users to select from) had the vendor error not occurred.

Incident Date
Nov 01, 2001
Setting
Equipment
  • Ventilation System
  • Glove Box/Fume Hood
Damage and Injuries
Probable Cause
Contributing Factors
When Incident Discovered
Lessons Learned

Personnel should be aware that items requiring special receiving inspections should still be verified/examined by the end user prior to use.

Given that the anaerobic chamber and associated nearby electrical equipment were not designed or expected to handle a potentially explosive atmosphere, nearly all conditions necessary to have a much more serious event were present if the problem had not been discovered and the bag was not successfully purged of the hydrogen mixture.

Hydrogen use in anaerobic chambers is discussed in the Lessons Learned Corner on this website.

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