Death by Nitrogen
Every year people die in nitrogen rich/oxygen deficient atmospheres because of ignorance, attitude and failure to
adhere to safe work practices.
BP – Incidents examples
Some of below based on Heritage BP Data
•
Kwinana, Aus – 1 injured - 1971
•
Vohburg, Ge - 1 injured - 1977
•
*Grangemouth, UK – 1 injured -1980
•
Alliance, USA - 1 injured - 1992
•
*Coryton, UK – 2 injured - 1998
•
BP Shipping – 2 injured - 2000
•
Fatality Lavera Chemicals, France –- 2001
•
Indonesia butterfly valve – near miss - 2001
•
Foinaven, UK 2 injured- 2001
•
Fatality Texas City Refinery 8th Aug 2001
•
Near Miss Open Vessel - *Carson Polypropylene 10 Aug 2001
•
Geel intoxication Nitrogen Near Miss- 13th Oct 2001
* Repeat in asset
BP – Incidents examples
• Canada - Fort Saskatchewan Nitrogen Exposure - 08 Nov 2001
• Baatan Nitrogen Release in Extruder House - Near Miss - 29 April 2002
• Fatality at PT PENI Indonesia - 13 Sept 2002
 *Coyrton Refinery Nitrogen Near Miss - 18 Oct 2002
• Near Miss Rockies working on improperly isolated Nitrogen system - 9 Dec 2002
• *Carson Refinery Nitrogen Near Miss - 29 Jan 2003
• Pasadena Nitrogen Near Miss - 7 Feb 2003
• Fatality -Fitter found dead inside railcar Belgium
(Possible N2 equip release issue)- 5 Feb 2003
• Nitrogen Near Miss Grangemouth Refinery - 11 March 2003
* Repeat in asset
Nitrogen (N2) vs. Oxygen (O2)
• Nitrogen is not toxic – it exists in air at 78%.
• Oxygen in the air is typically 20.8%
• When nitrogen concentration increases, oxygen
concentration decreases.
•
Note: any compressed gas can also decrease O2 concentration in an enclosed
space by replacing O2.
Facts & Figures
-Liquid nitrogen
• One litre liquid gives 700 litres of gas
• Cold nitrogen is heavier than air so accumulates at
ground level.
• When liquid N2 is exposed to air the cloudy vapour
that you see is condensed moisture, not N2 gas. N2
gas is invisible and this is the Danger!!!.
• OHSA recommend at least 6 changes of air per hour
when using liquid N2.
•
Other nitrogen risks: pressure, frost, confuse LEL detectors.
Medical definitions
• Osmosis: If you have a concentrated mixture on
one side of a permeable membrane and a dilute
mixture on the other, the flow of material will be from
concentrated to the dilute side.
• Hypoxia : reduction of O2 supply to the tissues
• Anoxia: lack of O2 supply to the tissues.
Transport of oxygen
Oxygen Osmosis
O2
O2flows
flowsfrom
fromhigh
highconcentration
concentrationtoto
low
lowconcentration.
concentration.
Concentration of O2
in the lungs is high
Concentration of O2 in the
tissues and Brain is lower.
Oxygen is transported from the lungs to cells, tissue and
brain via Osmosis.
What happens when you breathe in
nitrogen?
O2 flows from high concentration to
O2 concentration.
flows from high concentration to
low
low concentration.
O2 deficient air is
inhaled
Concentration
Concentration of O2 equalises throughout
the body.of O2 in the tissues
and Brain is higher than the lungs
•Reverse Osmosis
•Lungs take O2 from the blood stream which in turn takes it from the brain.
What happens when you breathe in
nitrogen?
•Brain becomes
starved of oxygen –
you pass out.
• You could say your
brain shuts you
down
•It only takes one
breath!
Physiological effects
Oxygen (%vol)
23.5
21
19.5
Effects & Symptoms
Maximum “Safe Level” OSHA
O2 level in air
Minimum permissible O2 level – (most detectors are set here or just above it)
15-19
First signs of hypoxia. Decreased ability to work strenuously. May induce early symptoms in persons with
12-14
Respiration increases with exertion, pulse up, impaired muscular coordination, perception & judgement.
10-12
Respiration further increases in rate & depth, poor judgement, lips blue.
8-10
Mental failure, fainting, unconsciousness, ashen face, blueness of lips, nausea, vomiting, inability to move
6-8
8 minutes – 100% fatal
6 minutes – 50% probably fatality rate
4-6
Coma in 40 seconds, convulsions, respiration ceases, death
How long does it take to have an
effect?
• When a person enters an oxygen deprived
atmosphere the oxygen level in the arterial blood
drops to a low level within 5-7 seconds.
• Loss of consciousness follows in 10-12 seconds.
• Heart failure and death ensue if person does not
receive any oxygen in 2-4 minutes.
What If I hold my breath?
• Holding your breath causes the oxygen in your blood
to be used up. If you then inhale the inert
atmosphere, suffocation and death will follow in
most cases (INRS ED 632)
Do I have to be in an enclosed
space to be at risk?
• No. Any situation where you can breathe oxygen
deficient air has the same effect.
• Incident at Texas City where individual was working
on top of reactor. He leaned over, got a blast of pure
N2 and pitched forward into the vessel unconscious.
• Cold nitrogen is more dense than air so lower
concentration at floor level. If you lean down into a
liquid nitrogen spillage you are also at risk.
The last word….
Nitrogen is a silent killer and demands
RESPECT…..!!!
PLEASE CONTROL IT AND
WORK AROUND IT PROPERLY
What if I see a colleague who is
unconscious?
• Call emergency services. - First as with all incidents
• Do not enter the area without self contained
breathing apparatus.
• Over 50% of workers who die in confined spaces are
attempting to rescue other workers.