SAChE Module Explosion Hazards
d
A discontinuous change in the gas density, pressure, and velocity of the air surrounding an explosion point is known as a: a. Side-on overpressure b. Pressure wave c. VCE d. Shock wave
c
A gradual change in the gas density, pressure, and velocity of the air surrounding an explosion point is known as a: a. BLEVE b. Reflected overpressure c. Pressure wave d. Shock wave
a
A reduction of oxidant concentration has little impact on the _____ until the oxidant concentration has almost reached the _____. a. lower flammability limit, limiting oxygen concentration b. upper flammability limit, limiting oxygen concentration c. upper flammability limit, lower flammability limit d. limiting oxygen concentration, lower flammability limit
N/A
Among other sources, the source of energy for a pressure vessel burst resulting in a physical explosion can be: 1. overfilling 2. combustion 3. phase change 4. chemical reaction
4, 1, 3, 2
Arrange the materials listed below from highest minimum ignition energy (MIE) to lowest by dragging them up or down in the list. 1. Combustible dust 2. Combustible vapor 3. Combustible aerosol 4. Combustible solids > 1 cm
a
Blast wave pressure fronts represented by this plot are known as (plot has a positive slope that stops at height p0, then drops down to pa (zero) and remains here): a. Shock waves b. Peak waves c. Pressure waves d. Gradual waves
b
Burning velocity _____ with turbulence a. remains unchanged b. increases c. decreases
small
Combustible particulates sufficiently _____ to burn rapidly when ignited.
partial
Confinement of the dust cloud by an enclosure or ____ enclosure.
b
Elbows, bends, and internal obstacles may increase turbulence _____ run-up distance. a. and increase b. and reduce c. but does not affect
a
Facilities are much more aware of dust explosion hazards as a result of which case discussed in this unit? a. Imperial Sugar Company b. Mexico City LPG terminal c. West Texas Fertilizer Company d. BP Texas City refinery e. Flixborough
2, 4, and 5
Factors that need to be considered to determine the distance a fragment could travel in an explosion include fragment: 1. Temperature 2. Trajectory 3. Color 4. Shape 5. Mass
b
Flux multiplied by exposure time is known as: a. Burn factor b. Thermal dose c. Hazard ratio d. Heat effect
a
For most flammable gases, an MIE of _____ is commonly used. a. 0.25 mJ b. 1.0 mJ c. 10 mJ d. 25 mJ
b
If a chemical reactor's process control fails, a _____ may occur that has the potential to overpressure the vessel, resulting in an explosion if the contents cannot be successfully vented. a. RPT b. runaway reaction c. BLEVE d. pressure vessel burst
d
If a vessel containing liquid propane suddenly loses containment, the pressure will drop and _____. a. the liquid propane will burst into flame b. the liquid propane will flow onto the ground and pose a pool fire hazard c. the liquid propane will freeze d. the liquid propane will flash to vapor
ignite
Ignition source of adequate energy or temperature to _____ the dust cloud.
b
In a combustible dust explosion, pyrolysis converts a portion of the dust particle into shorter chain molecule that are in _____ form and will then burn. a. solid b. vapor c. liquid
d
In a compartmented system in which there are separate but interconnected volumes, the pressure developed by the deflagration in one compartment can cause a pressure rise in the unburned gas in the the interconnected compartment. When the flame front reaches the second compartment, the explosion pressure is greater due to the increase in initial pressure. This is referred to as: a. 2-stage pressure b. Leading pressure c. Pressure transference d. Pressure piling
1, 3, and 5
In general, the AIT of a material decreases... 1. ...with increasing oxygen concentration 2. ...as mixtures become lean 3. ...with increasing pressure 4. ...as mixtures become rich 5. ...in the presence of catalytic surfaces
1 and 3
In general, the faster the fundamental burning velocity, the greater the potential for the fuel to: 1. Transition to detonation in a pipeline system 2. Cause a boiling liquid expanding vapor explosion 3. Generate hazardous pressures in a vapor cloud explosion 4. Transition to a deflagration in a pipeline explosion
1, 5, 6, and 7
In the list below, identify the activities representing hot work. 1. Burning 2. Boiler operation 3. Starting a combustion engine 4. Grinding 5. Cutting 6. Drilling 7. Welding
1 and 3
In the list below, identify two parameters used to characterize the explosive behavior for deflagrations? 1. Maximum oressure 2. Maximum temperature 3. Maximum pressure rate 4. Lower explosive limit
1, 3, and 4
In the list below, select the key elements required for a BLEVE to occur. 1. Containment that causes the pressure on the liquid to be sufficiently high to suppress boiling 2. A sudden drop in the temperature of the liquid 3. A liquid that exists above its normal atmospheric pressure boiling point 4. A sudden loss of containment to rapidly drop the pressure on the liquid
1, 2, 3, and 4
In what way(s) can ignition be achieved in the 20 liter sphere test? 1. A hot wire 2. A chemical igniter 3. An exploding fuse wire 4. A spark 5. A match
LOC
Oxygen concentration greater than the _____ for the suspended dust cloud.
1 and 3
Physical explosions can occur by: 1. RPT 2. Runaway reactions 3. Vessel rupture 4. Solid explosives, such as TNT
b
Static discharge incidents have most often been associated with: a. Cell phone use b. Transfer of materials c. Carpeted flooring d. Cold temperatures and low humidity e. Smoking
MEC
Suspended cloud of combustible particulates at a concentration above the ______.
true
TRUE or FALSE: Combustible aerosols are sometimes created intentionally.
true
TRUE or FALSE: Combustible liquid aerosols can lead to deflagrations.
false
TRUE or FALSE: Flammability limits (LFL and UFL) are always defined with respect to fuel mixtures with air, not other oxidants.
false
TRUE or FALSE: Minimum ignition energy values for most common materials used in the process industry are well established, with little variation between reported values.
false
TRUE or FALSE: Test data suggests that only aerosols in a confined cloud have the potential to explode.
false
TRUE or FALSE: The TNT equivalency method has been historically used for vapor cloud explosions (VCE) blast modeling because of its accuracy estimating blast energy for these types of explosions.
false
TRUE or FALSE: The elimination of ignition sources can be relied on as the primary defense against fires and explosions of gases and vapors.
True
TRUE or FALSE: The initial change in the gas density, pressure, and velocity of air that occurs with a blast can be either discontinuous or gradual
false
TRUE or FALSE: The negative phase of a blast wave does not contribute to the damage caused by the blast wave.
false
TRUE or FALSE: Toxics released due to an explosion are almost always consumed by fire and therefore communities surrounding process facilities are not considered to be at risk of exposure to toxics if the toxics were released as a result of an explosion
false
TRUE or FALSE: When panels are used for venting, the panels should have as much weight as the equipment being vented can withstand so that the panel can effectively contain the pressure generated by the explosion.
a
The AIT of a mixture generally _____ as mixtures become either rich or lean. a. increases b. decreases c. remains unchanged
b
The AIT of a mixture generally _____ as the test volume increases. a. increases b. decreases c. remains unchanged
c
The CCPS defines _____ as "construction of equipment (or a building) with weak section to limit the damage to the equipment (building)" a. explosion-mitigating construction b. deflagration-proof construction c. damage-limiting construction d. intentional weak design
d
The CCPS defines a/an _______ as "a release of energy that causes a pressure discontinuity or blast wave" a. pressure wave b. blast c. shock wave d. explosion
b
The CSB determined that the first dust explosion that occurred at the Imperial Sugar Company initiated in _____. a. the packaging area b. the enclosed steel belt conveyor c. a railcar at the bulk sugar loading area d. the office space adjacent to one of the sugar silos
d
The _____ is the lowest temperature at which a fuel-oxidant mixture will spontaneously ignite under specified test conditions. a. Minimum ignition energy b. Spontaneous ignition temperature c. Minimum ignition temperature d. Autoignition temperature
1, 2, 3, and 4
The ignition of a flammable material may result in which type(s) of fire? 1. Flash fire 2. Jet fire 3. Pool fire 4. Fireball
1, 2, 3, 4, and 5
The minimum ignition energy depends on: 1. Temperature 2. Concentration 3. Mode of ignition 4. The specific chemical(s) 5. Pressure
b
The transition from deflagration to detonation is referred to as a _____. a. slow flame front to fast flame front transition b. DDT c. pre-sonic to post-sonic transition d. D2D transition
b
Unlike _____, which allows the static charge to drain away, _____ equalizes the potential charges but does not eliminate the static charge. a. bonding, grounding b. grounding, bonding
1, 2, 3, and 4
What are the impacts of fragments and missiles produced by explosions at process facilities? 1. Secondary fires or explosions 2. Injury to people 3. Damage to storage tanks, process equipment and pipelines 4. Damage to structures
2, 3, and 5
What conditions must generally be present for a VCE to result in damaging blast loads? 1. The vapor m ust exist in an environment well above atmospheric pressure 2. An elevated flame speed must be achieved due to flame from acceleration 3. A flammable cloud of sufficient size must form prior to ignition 4. The vapor must be within a confined space 5. The released material must be flammable
a
What does the term "run-up distance" refer to? a. The distance between the steady deflagration and the formation of a steady detonation wave b. 10 times the diameter of the pipe in which a flame is traveling c. The distance the flame continues to travel after encountering an isolation device d. The distance between the flame front's current location and the isolation device
N/A
What hazards can contribute to the damage and injury caused by explosions? 1. Fireballs 2. Fragments/missiles 3. Blast effects 4. Secondary fires/explosions
2 and 3
What is the purpose of adding inert gas to a vessel containing a potentially flammable atmosphere? 1. Cool the vessel's liquid contents so that they are below the Lower Flammable Limit (LFL) 2. Lower the concentration of a flammable mixture to below the LFL 3. Lower the oxygen concentration below that of the LOC
N/A (not d)
What term is used by the CCPS to describe a system condition in which under no condition reactants or products are exchanged between the chemical system and its environment? a. Containment b. Inactive c. Secure d. Closed
a
What type of explosion occurred in the incident at the BP Texas City refinery? a. Vapor Cloud Explosion (VCE) b. Boiling Liquid Expanding Vapor Explosions (BLEVEs)
d
When a discontinuous change occurs in the gas density, pressure, and velocity of the air as a result of a blast, this is referred to as a ______. a. blast b. pressure wave c. explosion d. shock wave
b
When considering where occupied structures will be located during facility sitting analysis, what is perhaps the most important factor to keep in mind to protect against the effects of explosions? a. The flammability of the material in the process b. Separation distance between the occupied structures and the process c. The toxicity of the material in the process d. The location of firefighting equipment and firefighting personnel
b
When measuring blast wave pressure, if the pressure transducer is at right angles to the blast wave, the overpressure measured is called the: a. Peak wave b. Side-on overpressure c. Reflected overpressure d. Shock front
c
Which case discussed involved improper storage of a large quantity of explosible material near combustible material? a. Flixborough b. Mexico City LPG terminal c. West Texas Fertilizer Company d. Imperial Sugar Company e. BP Texas City Refinery
a
Which incident discussed in this unit resulted in the greatest loss of life? a. Mexico City LPG terminal b. Flixborough c. BP Texas City refinery d. Imperial Sugar Company e. West Texas Fertilizer Company
d
Which incident discussed in this unit was a cornerstone event that prompted the need to address process safety issues around the world? a. Mexico City LPG terminal b. Imperial Sugar Company c. West Texas Fertilizer Company d. Flixborough e. BP Texas City refinery
1, 3, and 4
Which of the following could apply to physical explosions? 1. Rupture of a pressurized gas or vapor-filled vessel 2. A runaway chemical reaction 3. Sudden phase-change from liquid to vapor of a superheated liquid 4. Rapid phase transition (RPT)
2, 3, and 4
Which of the following elements appear on both the dust explosion pentagon and the fire triangle? 1. Confinement 2. Oxygen 3. Heat 4. Fuel 5. Dispersion
c
Which of the following resources is best for understanding explosion vent sizing and design criteria? a. NEC b. NFPA 67 c. NFPA 68 d. NFPA 69
1, 2, and 3
Which of the following statements are true regarding damage-limiting construction? 1. The practice can be used to limit the equipment damage that might otherwise occur if a vessel were to rupture inside a building 2. NFPA 68 provides prescriptive design techniques for damage-limiting construction for dust and flammable vapor explosions 3. The practice attempts to direct the forces of the explosion away from other process equipment or potentially occupied areas 4. The practice is used to prevent damage to structures only
1, 2, and 4
Which of the following statements is/are true regarding the Imperial Sugar Company incident? 1. Airborne combustible sugar dust accumulated above the minimum explosible concentration inside the newly enclosed steel belt assembly 2. Emergency evacuation plans were inadequate 3. The conveying equipment was appropriately designed to minimize the release ofsugar and sugar dust into the work area 4. Inadequate housekeeping practices resulted in significant accumulations of combustible sugar dust
1 and 2
Which of the techniques and devices listed below represent active isolation: 1. Chemical suppression 2. Fast-acting mechanical valves 3. Deflagration and detonation arresters
2 and 3
Why were people and structures outside of the T2 Laboratories fence line affected by the explosion that occurred at the facility as a result of a runaway reaction? 1. Poor communication with the surrounding community 2. Structures with no blast protection 3. Poor sitting of occupied structures 4. The effects of the explosion could not have been anticipated
