In-Person PETS Final Exam - Petr Explosives Group.com

What is the maximum temperature allowed for blasting?

100 C
150 C
100 F
150 F

What is a misfire?

The charge failed to detonate after initiation
Fly rock occurred during blasting
You had to stop blasting due to bad weather

What is powder factor?

Specific amount of explosives used for blasting
Specific amount of explosives needed to break rock

A main charge with a detonator is known as a

Detonation train
Primer
DDT
High explosive

You can store high explosives and low explosives together

True
False

You must have at least 1 year of blasting experience to obtain a Colorado Type I Permit

Always true
Always false
It depends on the classification

What is the difference between blast site and blast area?

They are the same thing
The blast area is the area of the blast within the influence of flying rock missiles, gases, vibration, and concussion
The blast site is the area where explosive material is handled during blasting operations, including a distance of 50 feet in all directions from explosive charges
Both B and C are correct

If your explosive catches fire, you should

Put it out with water
Put it out with a fire extinguisher
Put it out by smothering the fire
Any of the above
None of the above

Emulsions and water-based explosives are the same thing

True
False

The detonation velocity of shock tube is approximately

18,000 feet/second
1,800 feet/second
6,500 feet/second
65,000 feet/second

When do you need to use a booster in your initiation system?

When your main charge is detonator sensitive
When your main charge is not detonator sensitive
When you want more power from your main charge
When you want less power from your main charge

What is the difference between a blast wave and a detonation wave?

They are the same thing
Blast wave is propagation outside of the explosive charge
Blast wave is propagation within the explosive charge
Detonation wave is propagation outside the explosive charge

What does DDT stand for?

Detonation to deflagration transition
Dynamic detonation train
Distributed detonation transition
Deflagration to detonation transition

What is a detonator?

A device or small sensitive charge used to detonate low explosives
A device or small sensitive charge used to detonate high explosives
A device or small sensitive charge used to initiate safety fuse
All of the above

What is a pull wire igniter used for?

Initiate safety fuse
Initiate a blasting cap
Initiate detonating cord
Initiate shock tube
All of the above

What is particle velocity?

The speed at which particles of fly rock leave the blast area
A measure of the intensity of the ground vibration
The speed at which air particles in the shock wave move
The speed at which the explosive chemical reaction proceeds

What is a detonation?

A loud explosion
Combustion of a substance which is initiated suddenly and propagates extremely rapidly
An explosive reaction that moves through the material at a velocity greater than the speed of sound in the material
None of the above

What is deflagration?

A loud explosion
Combustion of a substance which is initiated suddenly and propagates extremely rapidly
An explosive reaction that moves through the material at a velocity greater than the speed of sound in the material
None of the above

What is combustion?

The process of burning
The process of deflagration
The process of detonation
All of the above

How does shock tube work?

HMX/aluminum burns down the length of the tube
HMX/aluminum deflagrates down the length of the tube
A HMX/aluminum dust explosion down the length of the tube
HMX/aluminum propagates an electric current down the length of the tube

The explosive power comes from the ______ group in explosive compounds

Nitro (NO2)
Oxygen (O2)
Carbon monoxide (CO)
Nitrogen oxides (NOx)

Emulsions are more stable at higher temperatures

True
False

Blasting caps are:

High explosives
Low explosives
Blasting agents
None of the above

All explosives require oxygen from the air to detonate

True
False

Air voids (micro-balloons) are important for non-molecular explosives

True
False

Orange fumes mean

An oxygen-rich reaction resulting in NOx fumes
An oxygen-deficient reaction resulting in carbon monoxide (CO) fumes
An oxygen-balanced reaction
None of the above

For det cord, grain size will affect detonation velocity

True
False

Which explosive type(s) can be used directly in wet holes?

ANFO
Water gels/slurries
All of the above
None of the above

What is an advantage of using a non-electric initiation system over electric?

Non-electric systems will not disturb the explosive column
Non-electric systems are insensitive to lightning
Non-electric systems are insensitive to static electricity
All of the above

The numbers identifying various types of detonating cord refer to the number of grains of ______ that are contained within a linear _______ of cord.

Cord; inch
Explosive; foot
Explosive; pound
Black powder; foot

Explosives in a day box can be left unattended

True
False
Only if the day box is locked
Only if the day box is at a secured site

For the ATF, the minimum age to be an employee possessor is

16
18
21
There is no age minimum

What is true about a cut-off?

When detonating cord downlines are used, detonation of the cord in the blast-hole proceeds from the top down.
When the detonation of the cord may have an undesirable effect on the column charge as it proceeds downward, and the stemming may be loosened
When the hole is cut off by (burden) movement caused by detonation of an earlier hole the powder in the lower portion of the hole will not detonate.

The State of Colorado and the ATF must both inspect and approve a new explosive magazine

True
False
Only the ATF conducts magazine inspections; the State of Colorado does not have this authority
Only the State of Colorado conducts magazine inspections, the ATF does not have this authority

The ATF regulates the use of explosives across the United States

True
False
Only true for states that do not have their own regulations

You must have at least 1 year of blasting experience to be an ATF employee possessor

True
False
It depends on the classification

How should you handle a misfire?

The blaster shall provide proper safeguards for excluding all unauthorized persons from the danger zone if a misfire is found.
No other work shall be done except the necessary to remove the hazard of the misfire and only those employees necessary to do the work shall remain in the danger zone.
Explosives shall not be extracted from a hole that has misfired unless it is impossible or hazardous to detonate any unexploded explosive materials by insertion of an additional primer
If there are any misfires while using fuse detonators and safety fuse, all employees shall remain away from the charge for at least one hour. Misfires shall be handled under the direction of the person in charge of the blasting. All fuses shall be carefully traced, and a search made for the unexploded charges
All of the above

When can you use matches or other sources of fire or flame?

Anytime if you have a fire extinguisher a maximum of 15 feet away
When explosives are being handled or used
When you are 50 feet away or more from the blast site
When you are ready to blast
All of the above

A misfire referes to:

Any remaining blast hole or portion of a blast hole which contains damaged signal tube, electric detonator wires, detonating cord, or safety fuse
Any remaining portions of a charged blast hole (i.e. "cutoff" or "bootleg") which is suspected to contain explosives
Any unexploded charge or suspected unexploded charge
Any situation where a safety fuse has been used and the number of "shots" counted is less than the number of blast holes fired
Any situation where there is reason to suspect that explosive charges have failed to explode
All of the above

What instrument is used to measure resistance in a blasting circuit?

Ohmmeter
Battery charger
Galvanometer
Multimeter

Lighting, static electricity, and radiofrequencies are forms of _______ that are very hazardous.

Extraneous electricity
Flyrock
Airblast
Blast waves

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