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
