The document provides training on preventing explosions in dryers. It begins with an overview of the goals and content, which includes discussing a solvent explosion that occurred at the Sarrebourg plant in 2004. The causes of the Sarrebourg explosion are then examined in detail. The document reviews the fire triangle concept and explains what causes fires and explosions - namely, the presence of fuel, oxygen, ignition sources, and a rapid chemical reaction. Specific factors that lead to explosions in dryers are also addressed.

1. Preventing
Explosions in
Dryers
Alcan Packaging
EHS FIRST

2. EHS Central / Barbara Wüstenhagen 04/2007
This training module has been prepared by EHS Central to help you train your teams in this subject. It is
recommended that you review the slides and personalize them, as appropriate, for your own use. Feel
free to use all the slides, a selection or even to add your own slides.
We recommend that your training be of a "hands on" nature, as this approach is considered to be the
best way for people to learn and retain information, and that you integrate digital photos showing real
examples from your own site, wherever possible. These could include:
 Site best practices
 Opportunities/areas for improvement
 Current site practices
We would also recommend that you add some of your photos into the quiz section at the end of the
training.
This training was prepared using the experience and expertise we have within Alcan Packaging and was
put together so that you can profit from this and do not have to start developing your own presentation
on this subject from zero.
We are constantly trying to improve our training support to the plants. therefore we would really
appreciate your feedback on the added value of this training module as well as comments on its content
plus any photos/best practices you would like to share.
Thank you.
Foreword

3. EHS Central / Barbara Wüstenhagen 04/2007
 Understanding, identifying and controlling the
hazards leading to explosion
Goals

4. EHS Central / Barbara Wüstenhagen 04/2007
Content
 Sarrebourg Explosion
 What causes Fire and Explosion?
 Explosion Prevention in Dryers
 Reference Documents
 Quiz

5. EHS Central / Barbara Wüstenhagen 04/2007
FM Global Statistics
 From insurance losses between 1992-1997,
307 incidents were studied relating to ovens and
dryers.
 240 fires
 67 explosions.
Solvent Explosions are very common.
Why is this?

6. EHS Central / Barbara Wüstenhagen 04/2007
Alcan Packaging Statistics
 Alcan Packaging 1981-2004:
 475 fires of which 208 fires on printing and lacquering machines
 Alcan Packaging 2004:
 145 fires of which 69 fires on printing and lacquering machines
 Alcan Packaging 2005:
 92 fires of which 55 fires on printing and lacquering machines
 Alcan Packaging 2006:
 128 fires of which 80 fires on printing and lacquering machines
30 % of all fires in Alcan Packaging from 2004-06
occurred in printing and lacquering machines.
Not all
reported!

7. EHS Central / Barbara Wüstenhagen 04/2007
Location:
Lacquering station N°1
and the related dryer of
the extruder machine 117.
Injury :
4 workers located near the
machine were – by luck –
only slightly injured.
However, they were unable to
enter a workshop for 2 months
resulting in a loss due to Days
Lost of 200’000 €.
Sarrebourg Explosion
6 March 2004

8. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

9. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

10. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

11. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

12. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

13. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion

14. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion
Causes
1 - Chrome-plated depositing
cylinder running 1% faster
than web. Kiss coating.
2 - Pressure roll of the pull unit
open by operator.
3 - Automatic web tension
ineffective, web gets slack.
4 - Web dips into solvent tray.
5 - Many (????) kilos of varnish
fed into tunnel causing sudden
increase of solvent vapor.
Event 1: Sudden increase of solvent concentration in the air

15. EHS Central / Barbara Wüstenhagen 04/2007
Basic Principles
Generation
of charge
Lack of
discharge
Charge
Accumulation
Build up of energy
beyond ignition:
Static
Discharge:
Release of
a spark
A web gets static
charge by airflow
around roll, solvent
coating and running
around
rolls.
Sarrebourg Explosion
Causes
Event 2: Spark in the tunnel by electrostatic discharge
1 - Web gets static
charge by airflow
around roll, solvent
coating and run-
ning around rolls.
2 - Non-conductive
materials:
- Tissue paper 40g
- MEK
3 - Lack of controlled
discharge.
4 - Indoor air humidity
at 30% RH

16. EHS Central / Barbara Wüstenhagen 04/2007
Running Conditions
 Operator running as fast as possible with this product.
 LEL sensor reached control limit signalling operator to slow
down.
 Not enough tension to hold product flat.
 Operator made tension adjustment and left controls.
 Explosion occurred within 1 minute of this.
Sarrebourg Explosion
Causes

17. EHS Central / Barbara Wüstenhagen 04/2007
On line 117, these two events,
 increase of solvent concentration and
 electrostatic discharge,
occurring simultaneously led to an explosion in the tunnel.
Sarrebourg in brief
 Ineffective web tension allows web to dip into lacquer
 Sudden increase of solvent vapor results that atmosphere on
dryer exceeds LEL
 Ignition source existed in the dryer (or was exaggerated as the
explosive atmosphere grew)
 Explosive atmosphere detection could not respond quickly
enough
 Explosion relief or mitigation not present
Sarrebourg Explosion
Causes

18. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion
Damage
Explosion
Damage 1
2
3
4 5
Damage
1. Glass shattered
2. Walls and doors moved
3. Doors and vents moved
4. Sheeting opened
5. Sheeting opened
90 meters

19. EHS Central / Barbara Wüstenhagen 04/2007
Sarrebourg Explosion
Pressure
Sarrebourg must have had a pressure around 100 mbar inside the hall
after the dryers exploded.
 Serious level of death 500 mbar
 Dangerous level (1% lethality 140 mbar
 Windows usually shattered (all sizes) 35-70 mbar
 Frame distortion of steel frame buildings 140-170 mbar
 Rupture of oil storage tanks 210-280 mbar
 Steel framed buildings pulled from foundations 210 mbar
 Complete destruction of non-reinforced buildgs. 700 mbar

20. EHS Central / Barbara Wüstenhagen 04/2007
Content
 Sarrebourg Explosion
 What causes Fire and Explosion?
 Explosion Prevention in Dryers
 Reference Documents
 Quiz

21. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle
What causes Fire and Explosion?
Fuel
Ignition
Source
Oxygen
We normally talk of The Fire
Triangle consisting of the
three components:
1 - Fuel (Solvents)
2 - Oxygen
3 - Ignition Source (Heat)

22. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle
What causes Fire and Explosion?
Fuel
Ignition
Source
Oxygen
We normally talk of The Fire
Triangle consisting of the
three components:
1 - Fuel (Solvents)
2 - Oxygen
3 - Ignition Source (Heat)
A forth element comes on top
4 - The rapid chemical
reaction of combustion
Rapid
Chemical
reaction

23. EHS Central / Barbara Wüstenhagen 04/2007
What causes Fire and Explosion?
Fuel
Ignition
Source
Oxyge
n
Rapid
Chemical
reaction
This combination leads to a
FIRE
with little build up pressure.
When this occurs in a confined space,
we have an EXPLOSION
with increase in pressure & heat.
Fuel
Ignition
Source
Oxyge
n
Rapid
Chemical
reaction

24. EHS Central / Barbara Wüstenhagen 04/2007
What causes Fire and Explosion?
Explosion Types
DETONATION  occurs when the flame and pressure
wave move together above the speed
of sound.
 can not be relieved by explosion relief
panels
 pressure can achieve up to 20-50
atmospheres unless the container
ruptures first.

25. EHS Central / Barbara Wüstenhagen 04/2007
DEFLAGRATION  occurs when the pressure wave
moves together above the speed
of sound and the flame moves slower
than the speed of sound.
 A pressure relief may open to vent
vapour and reduce the maximum
pressure and temperature achieved.
 without venting the maximum
pressure could be up to 10 atmosphere.
Normally, in Packaging we suffer deflagrations.
The higher the pressure & temperature, the greater the damage.
What causes Fire and Explosion?
Explosion Types

26. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle
What causes Fire and Explosion?
Fire Triangle Elements
Fuel
Ignition
Source
Oxygen
 Oxygen comes from normal air
in the factory and heated drying
air.
 Fuel comes from the solvents
and solvent mixtures
evaporated during coating and
drying.
 Ignition sources include static
electricity, electrical equipment,
heating flames, electric
elements.

27. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle: Oxygen
Ignition can be prevented by
controlling oxygen level with
nitrogen or with CO2.
 With the high quantities of
circulation required to
evaporate solvents in
flexible packaging, it is not
practical to work with inert
(nitrogen) atmosphere.
 CO2 is a useful fire fighting
material but very dangerous
as it can kill people by itself.
 Normally we use air to avoid
an explosion by diluting
solvent vapour.
Fuel
Ignition
Source
Oxy-
gen
What causes Fire and Explosion?
Fire Triangle Elements
 Oxygen in the air is normally
about 21.6%.
 Ignition can take place with
oxygen levels as low as 8%.

28. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle: Fuel 1/2
*LEL = Lower Explosion Limit,
Is the concentration of solvents
within the mixture of oxygen and
solvent vapors below LEL, the solvent
vapor can not burn.
Fuel comes from solvents and sol-
vents mixtures evaporated during
coating and drying. The mixture is
only capable of igniting when within
a range of concentration in air:
**UEL = Upper Explosive Limit,
Is the concentration of solvents
within the mixture of oxygen and
solvent vapors too rich, the
solvent vapor can not burn.
Oxygen/
Solvent
Conc. in air
LEL*
UEL**
Explosive Window
Fuel:
e.g. Solvent
vapours
> LEL
Ignition
Source
Oxy-
gen
What causes Fire and Explosion?
Fire Triangle Elements

29. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle: Fuel 2/2
 Solvent vapor in air can just burn when
the LEL is reached.
 Solvent vapor in air can not burn when
the UEL is reached. For most solvents,
this can not be reached at normal tem-
peratures.
 In a closed container, most solvents
remain saturated in air as explosive
mixture above LEL.
 When operating dryers, we typically
plan to control with a factor of safety
of 4 by working at 25 % LEL.
(In some cases we run at levels of 50
% LEL as accepted by regulations).
We achieve that by ensuring that plenty
of air dilutes the solvent vapor.
Fuel:
e.g. Solvent
vapours
> LEL
Ignition
Source
Oxygen
What causes Fire and Explosion?
Fire Triangle Elements

30. EHS Central / Barbara Wüstenhagen 04/2007
Fire Triangle: Ignition Sources 1/2
Fuel
Ignition
Source
e.g.
Oxygen
Ignition Sources include
 Hot objects exceeding ignition
temperature of the solvent vapor in
the air (typically 400°C). This
includes sparks, flames and hot
surfaces.
 Electrical spark with enough energy
 Static spark with enough energy:
- Energy from a charged person is 10 milli J
- Energy to ignite solvents < 0.46 milli J.
 Dry Nitrocellulose
- reacts very easily with very little activation
energy when an exothermic reaction is
occurring or when it is very dry.
What causes Fire and Explosion?
Fire Triangle Elements

31. EHS Central / Barbara Wüstenhagen 04/2007
Minimum Ignition Energy of
Liquids and Gases
Basic Principles
[mJ]
Propane 0.65
Ethyl acetate 0.46
Propane 0.25
Methanol 0.14
Acetylene 0.017
Stored Energies of Objects
@ 10kV @ 30 kV
Road tanker 250 2500
Person 10 90
Bucket 1 9
100 mm Flange 0.5 4.5
11 mm Bolt 0.15 1.5
The Minimum Energy of our solvents are so low that
 the stored energy in a flange is greater than the minimum to ignite solvents
versus
What causes Fire and Explosion?
Enough Ignition Energy?

32. EHS Central / Barbara Wüstenhagen 04/2007
Minimum Ignition Energy of
Liquids and Gases
Basic Principles
[mJ]
Propane 0.65
Ethyl acetate 0.46
Propane 0.25
Methanol 0.14
Acetylene 0.017
Stored Energies of Objects
@ 10kV @ 30 kV
Road tanker 250 2500
Person 10 90
Bucket 1 9
100 mm Flange 0.5 4.5
11 mm Bolt 0.15 1.5
The Minimum Energy of our solvents are so low that
 the stored energy in a flange is greater than the minimum to ignite solvents,
 The stored energy in a bucket is 2-4 times greater than the minimum;
versus
What causes Fire and Explosion?
Enough Ignition Energy?

33. EHS Central / Barbara Wüstenhagen 04/2007
Minimum Ignition Energy of
Liquids and Gases
Basic Principles
[mJ]
Propane 0.65
Ethyl acetate 0.46
Propane 0.25
Methanol 0.14
Acetylene 0.017
Stored Energies of Objects
@ 10kV @ 30 kV
Road tanker 250 2500
Person 10 90
Bucket 1 9
100 mm Flange 0.5 4.5
11 mm Bolt 0.15 1.5
The Minimum Energy of our solvents are so low that
 the stored energy in a flange is greater than the minimum to ignite solvents;
 the stored energy in a bucket is 2-4 x greater than the minimum;
 the stored energy in a persons is 20-40 x greater than the minimum.
versus
 Man plus bucket is dangerous.
What causes Fire and Explosion?
Enough Ignition Energy?

34. EHS Central / Barbara Wüstenhagen 04/2007
Minimum Ignition Energy of
Liquids and Gases
Basic Principles
[mJ]
Propane 0.65
Ethyl acetate 0.46
Propane 0.25
Methanol 0.14
Acetylene 0.017
Stored Energies of Objects
@ 10kV @ 30 kV
Road tanker 250 2500
Person 10 90
Bucket 1 9
100 mm Flange 0.5 4.5
11 mm Bolt 0.15 1.5
The Minimum Energy of our solvents are so low that
 the stored energy in a flange is enough to ignite any of them,
 whilst that in a bucket is 2-4 times greater than the minimum to ignite;
 Persons themselves are 20-40 times more likely to ignite a vapor source.
versus
What causes Fire and Explosion?
Enough Ignition Energy?

35. EHS Central / Barbara Wüstenhagen 04/2007
Content
 Sarrebourg explosion
 What causes fire and explosion?
 Explosion Prevention in Dryers
 Reference Documents
 Quiz

36. EHS Central / Barbara Wüstenhagen 04/2007
Classification of Explosive Atmospheres
 Zone 2
 Do not expect explosive atmosphere to occur during
normal operation. If it does occur then will only occur
for a short time only.
 Zone 1
 An explosive atmosphere is likely to occur in normal
operation occasionally.
 Zone 0
 An explosive atmosphere is expected to occur in normal
operation continuously, frequently or for long periods of time.
 inside of tanks, parts washers
 in transition during coating and pouring.

37. EHS Central / Barbara Wüstenhagen 04/2007
Classification of Explosive Atmospheres
 Zone 2
 Equipment that is safe in normal operations.
Most affordable.
 Zone 1
 Only Equipment that is safe with known malfunctions.
Expensive.
 Zone 0
 Only equipment that is safe with known and unknown malfunctions.
Most expensive.
The Classification establishes the probability of an explosive atmosphere
and determines how safe equipment needs to be in them
regarding ignition source.

38. EHS Central / Barbara Wüstenhagen 04/2007
Explosion Prevention in Dryers
 Use an LEL sensor to monitor, alarm and shutdown when the LEL
becomes dangerously high (> 25 % with direct flame; > 50 % with
indirect heating).
 Ensure minimum solvent air quantity to limit solvent concentration to 25%.
 Do not recirculate solvent vapor over a flame or heating surface
above 300 °C.
 Ensure coating system can not coat with excess solvents.
 Ensure web dip can not occur during tension loss or web break.
 Use conductive solvents.
 Eliminate static wherever possible with active or passive eliminators.
 Clean up Nitro Cellulose residue frequently.
 Provide explosion relief panels or other means to limit explosion energy.

39. EHS Central / Barbara Wüstenhagen 04/2007
Content
 Sarrebourg Explosion
 What causes Fire and Explosion?
 Explosion Prevention in Dryers
 Reference Documents
 Quiz

40. EHS Central / Barbara Wüstenhagen 04/2007
Reference Documents
Alcan Packaging Standards
DRYING AIR RECIRCULATION AND OPTIMZATION
PACK 10KEY REQUIREMENTS
 Risk Assessment is necessary; supported by Appendix 1 highlighting
possible hazards, causes as well as recommendations.
 Alternative techniques for Air Re-circulation to be considered.
 Technical rules need to be followed for
 Design
 LEL and temperature monitoring
 Safe shut-down
 Activities prior to start-up
 Burner Safety
 Ductwork

41. EHS Central / Barbara Wüstenhagen 04/2007
Reference Documents
Alcan Packaging Standards
SOLVENT BASED PARTS WASHER
PACK 10KEY REQUIREMENTS
 Risk Assessment is necessary; supported by Appendix 1 highlighting
possible hazards, causes as well as recommendations.
 Authorized personnel only may have access to the solvent wash area.
 Design, Construction, Explosion relief, Ventilation, Passive and Active
fire protection of the wash-up room must be in line with local/national
country legislative requirements.
 Rules need to be followed for
 Management of the parts washer operation
 Linking the parts washer to the abatement system
 Ventilation of the area
 Grounding

42. EHS Central / Barbara Wüstenhagen 04/2007
Reference Documents
Alcan Packaging Standards
CONTROL OF ELECTROSTATIC IGNITION
SOURCES PACK 10KEY REQUIREMENTS
Electrostatic Source Evaluation to identify and evaluate all machines,
equipment, activities, actions and processes where there is a potential
for static build up and for either fire or explosion. Potential sources of risk
must be controlled.
Ensure effective Grounding of all solvent containers / equipment
Grounding clamps in good condition. Damaged grounding wires or
clamps immediately taken out of service.
Routine checking and cleaning program in place.
Personal Protective Equipment Requirements
Cotton (rich) clothing
Static dissipative footwear
Eyewear as well as face shields during liquid transfer operations
Rubber or appropriately suited synthetic gloves

43. EHS Central / Barbara Wüstenhagen 04/2007
Quiz

44. EHS Central / Barbara Wüstenhagen 04/2007
Quiz
 Summarize the sequence of events leading to the Sarrebourg explosion
 Describe the three element of the Fire Triangle?
 What is LEL and UEL?
 What can be ignition sources in dryers?
 The Classification of explosive atmosphere distinguishes three zones.
What is the definition of each zone?
 Where in our operation do we have Zone 0?
 List at least 5 explosion prevention measures in dryers.

45. EHS Central / Barbara Wüstenhagen 04/2007