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EXPLOSION PROTECTION
SOLUTIONS
by
Explosion Protection Solutions
Practical Guide on:
Explosion
Fundamentals Explosion Venting
Explosion Isolation
Explosion Suppression
Open air cornstarch deflagration
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Explosions by Industry
Factory Mutual Data Sheet 7-76
Industry Definitions
Explosionrupture of an enclosure due to the internal pressure from
a deflagration.
Deflagrationpropagation of a combustion zone at a velocity that isless than the speed of sound.
Detonationpropagation of a combustion zone at a velocity that is
greater than the speed of sound.
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Explosion Ingredients
Fuel
Enclosure
Ignition
Oxidant
PRESSURE
(BARA)
TIME
Explosion
KSt[dp/dt]max
Explosion Pressure Curve
10
0Normal pressure
Pmax
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Explosibility Index
KSt = (dp/dt)maxV1/3KSt = (dp/dt)maxV1/3
Kst
200201-300
>>>> 300
Kst
200201-300
>>>> 300
Hazard Class
St-1St-2
St-3
Hazard Class
St-1St-2
St-3
Pmax
10
10
12
Pmax
10
10
12
MATERIALParticle Size
MicronsPMAX
barg
KSt
bar-m/sec
Hazard
Class
COAL
(Bituminous)24 9.2 129 1
SUGAR 30 8.5 138 1
POLYETHYLENE
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Explosion Ingredients
FUEL:
OXIDANT:
IGNITION:
MEC minimum explosible concentration
LOC limiting oxidant concentration
MIE minimum ignition energy
MAIT minimum auto-ignition temperature
MEC minimum explosible concentration
LOC limiting oxidant concentration
MIE minimum ignition energy
MAIT minimum auto-ignition temperature
Knowing the Kst & Pmax ofyour product will define themagnitude and speed of anexplosion in your plant.
Knowing the MEC, LOC,MIE or MAIT can identify
process areas that aresubject to explosion.
If these values are notknown, Fike Corporationcan test your product inaccordance withrecognized procedures.
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Explosion Protection
3 Step Process
Define The Hazard
Define The Protection Objective
Choose The Protection Technique
Define The Hazard
Define The Protection Objective
Choose The Protection Technique
Define The Hazard
Process
Characteristics
Hazard
Characteristics
Physical
Characteristics
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T. Lombardo
9/30/97
T. Lombardo
9/30/97
Process Characteristics
Process Characteristics
Bag Filter
0 to - 17mbarg
Downstream
48C
Bag Filter
0 to - 17mbarg
Downstream
48C
Enclosure
Pressure
Blower
Location
Temperature
Enclosure
Pressure
Blower
Location
Temperature
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Hazard CharacteristicsHazard Characteristics
Pmax
KSt
MEC
MIE
MAIT
LOC
Pmax
KSt
MEC
MIE
MAIT
LOC
8.3 barg
120 psig
182 bar.m/sec
2,640 psi
90 g/m3
115 mJ
410C
12%
8.3 barg
120 psig
182 bar.m/sec
2,640 psi
90 g/m3
115 mJ
410C
12%
Physical Characteristics
Location
H/D
Volume
Clean
Dirty
Design
Strength
Location
H/D
Volume
Clean
Dirty
Design
Strength
Outdoors
1.8
10 m3
1.25 m3
8.75 m3
310 mbarg
Outdoors
1.8
10 m3
1.25 m3
8.75 m3
310 mbarg
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Define The Protection Objective
Control the
Explosion Pressure
Control the
Explosion Propagation
Control the
Explosion Pressure
and Flame
Control the
Explosion Pressure
Control the
Explosion Propagation
Control the
Explosion Pressure
and Flame
Choose The Protection TechniqueChoose The Protection Technique
Explosion Venting
Explosion Isolation
Explosion Suppression
Explosion Venting
Explosion Isolation
Explosion Suppression
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Venting Concept
A predetermined area Avreleases pressure at a given
level Pstat resulting in a
reduced pressure Pred.
Explosion flame, pressureand unburned mixture are
vented to a safe area.(the most widely used method)
PRESSURE
TIME
Explosion
KSt[dp/dt]max
Explosion Pressure Curve
Normal pressure
Pmax
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PRESSURE
TIME
Vented Explosion
Normal pressure
PREDPREDPstatPstat
PmaxPmax
PesPes
Venting
Efficiency
Venting
Efficiency
Physical Characteristics
Location
H/D
Volume
Clean
Dirty
Design
Strength
Pred
Location
H/D
Volume
Clean
Dirty
Design
Strength
Pred
Outdoors
1.8
10 m3
1.25 m3
8.75 m3
310 mbarg
310 mbarg
Outdoors
1.8
10 m3
1.25 m3
8.75 m3
310 mbarg
310 mbarg
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Process Characteristics
Bag Filter
0 to - 17 mbarg
100 mbarg
Downstream
48C
Bag Filter
0 to - 17 mbarg
100 mbarg
Downstream
48C
Enclosure
Pressure
Pstat
Blower
Location
Temperature
Enclosure
Pressure
Pstat
Blower
Location
Temperature
Explosion Vent SizingExplosion Vent Sizing
AV = 0.5 m2
VDI 3673,6.1.1 HomogeneousDust Distribution
AV = 0.5 m2
VDI 3673,6.1.1 HomogeneousDust Distribution
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YesYes
Location Location IndoorsIndoors
Discharge
Duct
Discharge
Duct
Explosion Vent SizingExplosion Vent Sizing
Discharge Relief Pred
Duct L Area
0 m 0.5 m 0.3 barg
2m 0.5m 0.86barg
1 m 0.4 barg
4m 0.5m 1.7 barg
1 m 1 barg
Discharge Relief Pred
Duct L Area
0 m 0.5 m 0.3 barg
2m 0.5m 0.86barg
1 m 0.4 barg
4m 0.5m 1.7 barg
1 m 1 barg
Explosion Vent SizingExplosion Vent Sizing
L
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Available in many sizes and
shapes Diversity of materials &
designs process (compatibility)
Low cost, long life expectancy
Must vent to a safe location(outdoors)
Available in many sizes and
shapes Diversity of materials &
designs process (compatibility)
Low cost, long life expectancy
Must vent to a safe location(outdoors)
Explosion Vents
Highest efficiency
Low unit mass < 12.2 kg/m
Certified burst pressures
Full predictable opening
Non-Fragmenting
Low maintenancerequirements
Flameless Explosion Venting
An alternative to the use of
explosion discharge ducts is
the use of Vent Flame Filters
in combination with explosion
venting.
While the explosion is allowed
to run full course inside the
protected equipment, only
pressure will be vented into
the surrounding atmosphere
and a secondary explosion
risk is prevented.
An alternative to the use of
explosion discharge ducts is
the use of Vent Flame Filters
in combination with explosion
venting.
While the explosion is allowed
to run full course inside the
protected equipment, only
pressure will be vented into
the surrounding atmosphere
and a secondary explosion
risk is prevented.Flameless Venting
Conventional Explosion Venting
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Bucket Elevator Vents
The EleGuard vent is specifically designed for
Bucket Elevator Explosion protection
The number of vents is required is determined by
the Kst, design Strength of the leg and height of the
legs
Indoor Venting of Bucket Elevators
The EleQuench device is designed for Bucket
Elevator Explosion protection where the Elevators
are located Indoor
An Indicator called an RI is recommended as this
indicates that the Vent has opened
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VENTING SUMMARY
ADVANTAGES
Relatively inexpensive
Easy to install or replace
Low maintenance
Passive system
CONSIDERATIONS
Releasing pressure does not put out the flame. Flame,
pressure and unburned products will exit through thevent and may cause further damage or injury.
Toxic products may be dispersed into the atmosphere.
More Vent area than can practically be installed may
be needed.
EXAMPLES
VENTING
OF SILOS
VENTING OF
PIPELINES
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EXAMPLES
Explosion Protection Solutions
Practical Guide on:
Explosion
Fundamentals Explosion Venting
Explosion Isolation
Explosion Suppression
Open air cornstarch deflagration
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Explosion Isolation
Why Isolation ?Why Isolation ? Explosion pressure and flame will propagate
through process interconnections to other plant
equipment or personnel occupied areas.
Explosions in connected vessels tend to be of
higher severity than explosions occurring in
single unconnected vessels because of pre-
compression and flame-jet ignition.
Deflagrations can accelerate to detonation
velocities while traveling through pipelines.
Explosion pressure and flame will propagate
through process interconnections to other plant
equipment or personnel occupied areas.
Explosions in connected vessels tend to be of
higher severity than explosions occurring in
single unconnected vessels because of pre-
compression and flame-jet ignition.
Deflagrations can accelerate to detonation
velocities while traveling through pipelines.
Explosion Pressureand Flame
Propagation inBucket Elevator
Explosion Pressureand Flame
Propagation inBucket Elevator
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Explosions inInterconnected Enclosures
P = 7.4 bardP/dt = 32 bar/s
P = 7.4 bardP/dt = 32 bar/s
P = 7.4 bardP/dt = 55 bar/s
P = 7.4 bardP/dt = 55 bar/s
V = 1.0 m3V = 1.0 m3
V = 5.0 m3V = 5.0 m3
P = 11 bardP/dt = 1.200 bar/s
P = 11 bardP/dt = 1.200 bar/s
P = 10.2 bardP/dt = 1.000 bar/s
P = 10.2 bardP/dt = 1.000 bar/s
V = 1.0 m3V = 1.0 m3
V = 5.0 m3V = 5.0 m3
Explosions in
Interconnected Enclosures
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Chemical Explosion-isolation System
No restriction, clean procesconnection
Only to be used in combination with explosion venting or
explosion suppression (Pred Pmax)
only stops the explosionflame, not the explosionpressure
different suppressant agents are available, depending on
the application requirements (food industry, CIP, metal
dust explosions, etc.)
No restriction, clean procesconnection
Only to be used in combination with explosion venting or
explosion suppression (Pred Pmax)
only stops the explosionflame, not the explosionpressure
different suppressant agents are available, depending on
the application requirements (food industry, CIP, metal
dust explosions, etc.)
0.3 m min10 dia. max
Xmax
Xmin
Explosion IsolationExplosion Isolation
Fike
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Define The Protection Objective
Control the
Explosion Pressure
Control the
Explosion Propagation
Control the
Explosion Pressure and
Flame
Control the
Explosion Pressure
Control the
Explosion Propagation
Control the
Explosion Pressure and
Flame
Choose The Protection TechniqueChoose The Protection Technique
Explosion Venting
Explosion Isolation
Explosion Suppression
Explosion Venting
Explosion Isolation
Explosion Suppression
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Suppression Concept
The heat of combustion develops pressure.
Upon pressure detection, sufficient
suppressant agent is dispersed into the
protected volume.
Flame is quenched which prevents any further
pressure increase.
Flame, pressure and unburned mixture arecontained inside the vessel
IgnitionSpark/Flame starts in a closed vessel
equipped with detector, control panel and suppressant
container
Fike
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DetectionDetector senses pressure wave and sends signal to controlpanel
Time : LESS THAN 1 Milliseconds
Fike
Fike
ActivationControl Panel issues command to suppressant container.
Initiator opens rupture disc. Time: less than 1 millisecond
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InjectionSuppression agent released through dispersion nozzle.
Fike
SuppressionContainer continues to release agent. Explosion is
suppressed.
Response time is measured in Milliseconds
Fike
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PRESSURE
TIME
Explosion
KSt[dp/dt]max
Explosion Pressure Curve
Normal pressure
Pmax
Explosion Suppression
ADVANTAGES
Process media is contained
It can be used inside buildings - near personnel -
Provides fire protection (after initial deflagration)
Can provide automatic process shutdown
CONSIDERATIONS
Active system
Requires regular maintenance
CONSIDERATIONS
Active system
Requires regular maintenance
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Explosion risks are an industrial reality;
equipment loss, downtime, environmental
issues and hazards to personnel can be
avoided through the application of the most
suitable protection method.
Explosion protection technology offers
the process and safety engineer a
variety of reliable tools.
Fike Explosion Protection Solutions
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