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TRANSCRIPT
GEAPS Great Lakes Regional Conference 2017
Explosion Protection Overview & Market Drivers
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April 6, 2017
Outline
• Combustible Dust Overview
• Explosion Protection Market Drivers
• Technology Options
• Questions
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Combustible Dust Definition
Very small particles become airborne settling on surfaces and within crevices throughout the manufacturing area
Lighting, pipes, dust collectors, other equipment
When disturbed, they can create dispersed clouds of combustible dust = explosion risk
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Dusts diameters are typically less than 500 micron but ‘surface
area-to-volume’ is a key factor in rate of combustion, so shape
influences combustion properties.
Combustible Dusts
• Metals dust such as aluminum, magnesium, titanium, or steel
• Wood or wood products
• Coal or other carbon dust
• Plastic dusts or additives
• Organic dusts such as sugar, paper, soap, or dried blood – even chicken poop
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Quick Terms – Dust Properties
Kst Deflagration Index for dust - The maximum rate of pressure rise during a contained deflagration of an optimum mixture [bar*m/sec]
Pmax Maximum Pressure - maximum pressure developed in a contained deflagration of an optimum mixture [bar]
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Flame and Pressure Growth in a Vessel
PR
ES
SU
RE
(B
AR
A)
Time
10
0
Pressure Wave – 1100 ft./sec.
Flamefront – 80 ft./sec.
KSt
[dp/dt]max
Pmax
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Equipment Involved in Dust Explosions
Locations
US
(1985 – 1995)
UK
(1979 – 1988)
Germany
(1965 – 1980)
Number of
Incidents
% Number of
Incidents
% Number of
Incidents
%
Dust Collectors 156 42 55 18 73 17
Grinders 35 9 51 17 56 13
Conveying Systems 32 9 33 11 43 10
Silos/Bunkers 27 7 19 6 86 13
Dryer/Oven 22 6 43 14 34 8
Mixers/Blenders >12 >3 7 2 20 5
Other or Unknown 84 23 95 31 114 27
Total 372 100 303 100 426 100
Source: Guidelines for Safe Handling of Powders and Bulk Solids, CCPS, AICHE9
How to tell if your process dust is combustible?
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• Is my dust Combustible?
Easy way – Sparks? Fire? Combustible Event?
Test the dust – Find out: Go No Go
Minimal heat or energy to combust
MIE – minimal Ignition Energy – millijoules
MEC – Minimal Explosible Concentration – How much dust?
Pressure signatures Explosion Severity Test – Kst / Pmax
Shouldn’t I be GRANDFATHERED???
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Bartlett Grain Atchison, KS October 29, 2011 6 Fatalities & 2 Injuries
(Grain Dust 9x more explosive than coal dust)
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From 1980 - 2014
• 330+ MAJOR Combustible Dust Incidents N.A.
• 150+ Workers Killed
• 879+ Workers Injured
• $$ BILLIONS in Damages
• CSB Final Report November 2006• The Danger of Combustible Dust – NYT August 2014
Organizations Involved
• U.S. Chemical Safety Board (CSB) Investigation Report / Combustible Dust Hazard Study
• Occupational Safety & Health Admin (OSHA) National Emphasis Program
• National Fire Protection Association (NFPA) Codes & Standards – NFPA 652 / NFPA 61
• Authorities Having Jurisdiction (AHJs) OSHA
Fire Marshall
City Inspectors
Insurance Companies14
NFPA Standards Guiding Safety –Combustible Dust
• Standards Around Combustible Dust
• Occupational Safety & Health Admin (OSHA) National Emphasis Program
• National Fire Protection Association (NFPA) Codes & Standards
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Standard Description
NFPA 61 Standard for the Prevention of Fires and Dust Explosions in Agriculture & Food Processing Facilities (2017)
NFPA 652 Standard on Fundamentals of Combustible Dust (2016)
NFPA 654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids (2017)
NFPA 655 Standard for Prevention Sulfur
NFPA 484 Standard around Combustible Metals
NFPA 664 Standard around Wood Processing (2017)
NFPA 68 Standard on Explosion Protection by Deflagration Venting
NFPA 69 Standard on Explosion Prevention Systems
NFPA 652 (2016) – Effective September 2015
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• New Hierarchy for commodity / Industry Standards Closest we’ve been on national standard
• Process owner fully responsible Unawareness no longer acceptable
• DHA Protocol – September 30, 2018 3 Year Mandatory (now out of date)
• Hazard Management NFPA 652 cross-references with NFPA 68 / NFPA 69
Stresses Isolation
NFPA 61 (2017) – Effective June 2016
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• New Emphasis on Mitigation (Ch. 4.2.4)
• Clear Language on Responsibility (Ch. 5.1) Extensive Cross-Referencing to NFPA 652
Absence of previous incidents shall not be used as basis for determining if particulate is combustible (Ch.5.2.3)
• Hazard Identification added 3 options (Facility History, Published Data, or Testing Option)
• Performance-Based Design chapter present in all new generation NFPA Standards (Ch. 6) Modeling / testing meets AHJ’s satisfaction then you can do it!
• New Chapter 7 - DHA 5 year deadline for existing processes (652 = 3 year)
Which Solution is the Customers’ Preference?
• Nothing
• Venting
• Ducted Venting (often not possible)
• Building Venting (low awareness)
• Suppression / flameless Venting
• Containment
• Inert Gas / Oxygen Reduction 18
Most Requested
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WHEN TO CONSIDER USING EXPLOSION VENTING
1. Flame trajectory and pressure wave can be safely released to atmosphere
2. Equipment is either outdoors…
3. Or Indoors but safely ducted through outside wall
One hydraulic diameter
Types of Explosion Vents
Flat single Section Vents
Single Section Construction
Round or Rectangular
Center or Perimeter Burst
Limited Vacuum Resistance
Poor Cycle Resist. (req. support)
Sanitary Option
300F – 2000F with insulation
Storage Systems with no operating pressure fluctuations
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Types of Explosion Vents
Composite Vents
Layers
SS/Teflon/SS
Round or Rectangular
Center burst
Limited Vacuum Resist.
Fair to good Cycle Resist.
NOT Sanitary
400F-1000F (with Ins.)
High Temp Applications
High Vacuum (round)
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Types of Explosion Vents
Round / Rectangular Compound Domed Vent
Solid One-Piece Design
Round or Rectangular
Perimeter Burst
Good Vacuum Resistance – Full Vaccum
Excellent Cycle Resistance
Sanitary
300F-2000F (with Ins.)
Good for all Applications
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Magnetic Burst Sensor
MBS Sensor is designed for use in an intrinsically safe circuit and shall be used to shut down the process to
end the supply of combustible material into a piece of equipment and to trigger an Isolation device
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Lead Time & inventory
• Lead Time Stock Items
Custom Items
• BS&B Inventory Management System (BIMS)
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Flameless Vents
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BS&B Systems IQR flameless Vent
(Intercept, Quench, & Retain)
BS&B Systems R -IQR flameless Vent
(Rectangular)
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WHEN TO USE FLAMELESS VENTING
1. Flame trajectory is unsafe
2. Equipment is indoors
1. Vent Ducts would be too long
3. Cannot release the dust to atmosphere
4. Pressure shock of venting is unacceptable
5. Concern at negative publicity of simple venting
Flameless Vents
• Four Safety Functions of Flameless Vents
Flame Arresting – No flame escapes providing for safe operating environment.
Reduces and/or Eliminates a secondary ignition
Dust Retention – Retains process dust after an event
Pressure Absorption– Reduces explosion pressure peak
Temperature Control – Absorbs flame front with negligible temperature rise.
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Vents & flameless Vent Facts
Passive Protection– Relieves pressure
Vent is sized according to strength of the vessel
Opens prior to damaging integrity of the vessel
NOT completely passive
Yearly Inspection – NFPA 68
Also requires isolation - NFPA 652
Can flameless Vents be Reused?
Only on pneumatic activations
Vent needs replacing
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flameless Vent Efficiencies
• Rectangular Vents 64-85% Efficiency• 135o Venting (face)• ~15sq ft Surface Area• Dust Hazard Zone 7ft / Personnel 3.5ft• Vertical or Horizontal Installation• Maximum of 500Kst / 10.0 Pmax
• Round Vents 95% Vent Efficiency• 360o Venting (face)• ~67sq ft Surface Area• Dust Hazard Zone > 1ft / Personnel N/A• Vertical or Horizontal Installation• Maximum of 500Kst / 10.0 Pmax
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R-IQR Rectangular Flameless Vent
Configuration
• Vent installation opening also allows periodic inspection without removal of R-IQR from service.
Design Benefits
• Both Models Extreme Level of Protection 500 Kst / Pmax 10.0
• Both Models ATEX / EN Compliant
• R-IQR Trap Door for Inspections & Installation
• Burst Sensor to Trigger Isolation Device along with Shut-down Process
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When to use Suppression?
1. The customer wants to avoid the full combustion process:
- Unable to accept flame ball release
- Unable to accept release of material (toxicity, cost, etc.)
- Require fast clean up and restart of process without repair to the protected equipment
2. Can be the most cost effective approach:
• - Typically more economic than multiple flameless vents
• - Allows combination with Isolation in a single system
3. Flexible with respect to a wide range of shapes and
• volumes requiring protection:
• - Compact Cannon construction, low mass
• - Ability to install BS&B Cannons in almost any orientation 38
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Suppression In Action
PressureDetector
Fireball 30 ft/sPressure Wave 1,100 ft/s
N2 Suppressant
Suppressor
Fireball
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When Design Matters
System Monitor
Triplex Explosion Pressure Sensor
Suppression Cannon
Power Supply
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Customer ReplaceableSuppressant Canister
Suppression Cannon Design
Light Weight Low Pressure Nitrogen
Tank
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The Cannon Installation Advantage
Mounting requirementwithin 10 degrees vertical
Traditional Design Disadvantages:Requires Delivery Pipe Work• Increases Installation cost• Slows Agent Delivery• Adds Blockage Potential
N2
Agent
N2 Agent
The Cannon Advantage:• Enables mounting at any angle• Speeds agent delivery• Eliminates need for costly pipe work
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View of Triplex Sensor Assembly
Process Side
Triplex Sensor Features:
Three Pressure Sensors in One Housing;
2 must trip at the same time to trigger system; 2/3 voting logic
Face 3 different directions; reduces chance of product impact or vibration induced unwanted activation.
CutawaySide view
Pressure Sensors (3)
Design Benefits
• Only requires 1 visit per year from BS&B Quarterly Inspections to be Handled by I-Paper Staff
Saving $$$$ per quarter (x each system)
• Spare Parts Can be Stored ON SITE Greatly Reduced Down-Time for System Refit
I-Paper Staff to Perform Refit – Saving $$$$$
• Control Panel – Output to I-Paper Master Panel
• All Components (with exception of conduit) Included in Sale.
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Next Steps
Venting
Dust Type (grain, metal, etc.)
Kst
Pmax
Pred
Drawing (or dims for volume)
Explosion Protection
Dust Type (grain, metal, etc.)
Kst
Pmax
Drawing (or dims for volume)
Duct Diameter (Isolation)
Sensor type (for Isolation)
Destination Country
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Information needed to generate quotes…