D7 Flashcards
What is a key consideration in the development of the CEC?
The prevention of fire.
LT1 PG8
A hazardous location is an area in which…
Either explosive gas or dust atmospheres exist or may exist
LT1 PG8
To achieve a reduced ignition risk what two fundamental things are necessary?
1) hazardous locations are correctly identified and classified.
2) designers and installers abuse by the rigorous requirements for electrical installations.
LT1 PG8
Who is a qualified person that can carry out and document the classification of a hazardous location?
Professional engineers.
LT1 PG8
For small areas, the classification may be performed by?
A single discipline of engineer.
LT1 PG8
For large facilities the classification of hazardous locations would be done by?
Multiple disciplines of engineer, collaboratively.
Process engineers, heating and ventilation engineers, electrical engineers, and so on.
LT1 PG8
What section of the CEC is standards of the zone classification system found in?
Section 18
LT1 PG9
What are zones 0, 1, and 2 used to classify?
Explosive gas atmospheres.
LT1 PG9
What are zones 20, 21, and 22 used to classify?
Explosive dust atmospheres
LT1 PG9
Likelihood is based on what two factors?
Frequency explosive atmosphere would be present.
Amount of time explosive atmosphere would be present.
LT1 PG9
The likelihood of explosive atmospheres being present is captured in numerical order of the zones. Does the likelihood increase or decrease from zone 0 to zone 2?
Decrease.
The lower the number the higher the frequency/time of explosive atmosphere.
LT1 PG9
What is a “group”?
A sub-classification within a zone that distinguishes between different types of gases and dust.
LT1 PG9/10
What system was used to classify hazardous locations previous to the zone/group system?
Class/division system.
LT1 PG10
What is a hazardous location?
The class/division system of classification for hazardous locations is based on IEC standards.
False.
It is the zone system of classification that is based on IEC standards.
Self Test 1
In the zone system, each zone is further broken down into divisions.
False.
They are broken down in to groups.
Divisions are used in the class system.
Self Test 1
Facilities already using the class/division system may continue to use this system for additions.
True
The CEC includes provisions for this in 18-000 3)
Self Test 1
Under the zone system of classification, acetylene would be categorised into group…
C - group IIC
Self Test 1
Under the zone system of classification, the least hazardous gases are categorized under group…
A - Group IIA
Natural gas is classified into group IIA in the zone system, provided that it contains no more than __% hydrogen.
25%
Self Test 1
What does LFL stand for?
Lower flammable limit
Self Test 1
What does UFL stand for?
Upper flammable limit
Self Test 1
In the zone system, groups are arranged based on relative hazard in _____ alphabetical order. This means?
Ascending alphabetical order.
A is least hazardous
C is most hazardous
LT1 PG12
In the class/division system, the groups are arranged based on relative hazard in ______ alphabetical order. This means?
Descending
For gas:
D is least hazardous
A is most hazardous
For dust:
G is least hazardous
E is most hazardous
LT1 PG12
Zone 0
Gas
Present continuously or for long periods
LT1 PG9
Zone 1
Gas
Likely to occur in normal operation / adjacent to zone 0 area
LT1 PG9
Zone 2
Gas
Not likely to occur in normal operation, is for short period if it does / adjacent to zone 1
LT1 PG9
Zone 20
Dust
Present continuously for long periods or frequently
LT1 PG9
Zone 21
Dust
Likely to occur in normal operation
LT1 PG9
Zone 22
Dust
Not likely to occur in normal operation, is for short periods if it does.
LT1 PG9
What are the two most important factors to consider to ensure equipment installed within a hazardous location is safe?
1) whether the equipment could cause ignition either in normal operation or in the event of a failure.
2) whether the equipment enclosure has the ability to contain an explosion within the equipment without causing ignition of the explosive atmosphere
LT2 PG16
Intrinsically safe electrical systems and non-incendive wiring circuits are similar in design and application. What 3 components do they generally consists of?
Field barrier device
Barrier device
Associated wiring
LT2 PG16
Where is the field barrier device installed?
Within the hazardous location
LT2 PG16
Where is the barrier device installed?
In the non-hazardous location.
LT2 PG16
What does an “explosion proof” rating indicate?
That if installed correctly, the enclosure is capable of safely containing an explosion within in.
What does an “explosion proof” rating indicate?
That if installed correctly, the enclosure is capable of safely containing an explosion within in.
LT2 PG17
Which system (zone/group, class/division) is the term “explosion proof” applicable to?
It is only applicable to the class/division system
Is also most often associated with NEMA 7 ratings.
LT2 PG17/18
Which system is the term “flameproof” applicable to?
It is applicable to the zone/group system.
It is the equivalent term to “explosion proof” from the class/division system.
LT2 PG18
What does the temperature class of equipment relate to?
The maximum surface temperature that the enclosure or equipment will rise to.
LT2 PG19
What are Equipment Protection Levels (EPL)?
EPL is a comprehensive rating system that overrides other factors and must be followed if present.
LT2 PG19
