Test Question disagreement

[KentAT]

This is a test question from a testing company, included as a sample question for their test for certification as an Electrical Inspector.

I do not agree with the answer as listed on their answer sheet.

4. A location in which, under normal operating conditions, hazardous concentrations of flammable vapors exist intermittently is designated as
(A) Class I, Division 1
(B) Class I, Division 2
(C) Class II, Division 1
(D) Class II, Division 2

What say you?

 

[BPoindexter]

"Intermittently" ??

My best guess is they mean they are present during normal operating conditions. So I am going to guess C1D1 :blink:

 

[petersonra]

"Intermittently" ??

My best guess is they mean they are present during normal operating conditions. So I am going to guess C1D1 :blink:

yep.

 

[KentAT]

ANSWER:

The sample test answer sheet says B.
I say that's B.S.
The info clearly fits the definition of Div 1, and has none of the qualifiers that suggest it can be a Div 2.
I sent them an email asking them to explain their answer, but of course no reply.

Kent

 

[Smart $]

...
I sent them an email asking them to explain their answer, but of course no reply.

...

I doubt they have any qualified persons on staff.

 

[ritelec]

scroll to REVIEW

http://www.osha.gov/doc/outreachtraining/htmlfiles/hazloc.html


looking in the book to make heads or tales of it.
From what I understand of the test writers, they write tests for lawyers, doctors,elec.,plumb. etc...these test writers write questions from the book. If it is not in the book, it is the wrong answer.

 

[ritelec]

I would have to say C1D1 also.


I'm only picking up accidental in D2.........The question reads intermittently (would that be many accidents)....ha ha ha.

 

[james_mcquade]

KentAT,
i would say the answer is "B".
the key word to me is intermittent.

C1D1 is an area in which hazardous gases are present during normal production.
C1D2 is when the gases are present during an abnormal condition hence intermittent.

i don't have the code book at this site. look in the class 1 section under division 1,2,3 definitions.

regards,
james

 

[Smart $]

KentAT,
i would say the answer is "B".
the key word to me is intermittent.

C1D1 is an area in which hazardous gases are present during normal production.
C1D2 is when the gases are present during an abnormal condition hence intermittent.

i don't have the code book at this site. look in the class 1 section under division 1,2,3 definitions.

regards,
james

Read the statement again. It says under normal operating conditions.

 

[jim dungar]

C1D2 is when the gases are present during an abnormal condition hence intermittent.

That is what I would have chosen.

 

[ritelec]

C1D1 is an area in which hazardous gases are present during normal production.
C1D2 is when the gases are present during an abnormal condition hence intermittent.

intermittent.is a normal condition.
accidental is an abnormal condition.
The code not not say any thing in reference to "the word" intermittent". That I could find.
I was leaning toward D2 as explained, above. The righters of the test.......but I think someone added the word "intermittent" .if the system was designed "intermittent" it would have to be D1. If accidental (which does not mean the same thing as the word intermittent ..) then D2.
But I must say I think they goofed.

That is what I would have chosen.

Now me too. (I think the testateers goofed)

Read the statement again. It says under normal operating conditions.

yep and I was leaning that way...but I got to say now C1D1.

http://www.merriam-webster.com/medical/accident
http://www.thefreedictionary.com/intermittent

I think a writer of the test goofed and added his/her own wording.

 

[rbalex]

The fundamental relevant definition [500.5(B)(1)] is: A Class I, Division 1 location is a location in which ignitible concentrations of flammable gases, flammable liquid produced vapors, or combustible liquid?produced vapors can exist under normal operating conditions.

The duration or frequency is irrelevant. It only has to be a ?normal? condition. In fact, where it relieves to atmosphere, the exhaust port of a relief valve is still Class I, Division 1 even though it may never activate.

Normal is not well defined with respect to hazardous locations. For example, starting a motor is not considered "normal" [see Section 500.8(B)(5)] This is also a key reason the NEC isn't "intended as a design specification or an instruction manual for untrained persons." [90.3(C)]

 

[ritelec]

What's you vote?

 

[ritelec]

The fundamental relevant definition [500.5(B)(1)] is: A Class I, Division 1 location is a location in which ignitible concentrations of flammable gases, flammable liquid produced vapors, or combustible liquid–produced vapors can exist under normal operating conditions.
]

would normal me intermittent? It could be, but I see nothing to show intermittent as being normal.

Normal This is also a key reason the NEC isn't "intended as a design specification or an instruction manual for untrained persons." [90.3(C)]

With all respect.......master.......are you trained....give a vote please....Really most humbly....Rich

 

[BPoindexter]

It is a bad question no doubt about it. Normal doesn't mean it is always present either. Give you an example-pigging module. Inserting and extracting the pig is a "normal" operation. During this time the barrel is open and crude vapors are venting into the room. However this may happen once per month, once per day, or several times a day. As Bob points out duration is irrelevant. I have only recently seen pigging modules that are C1D2 but that is only beacuse of the uber HVAC systems installed that provide many many air changes per hour.

 

[rbalex]

What's you vote?

I was the first to vote Class I, Division 1 in the pole.

My experience?:

• [*=1]Principal Member of Code Making Panel 14 (Arts 500-516), 2002 NEC[*=1]Principal Member NFPA Technical Committee on Electrical Equipment in Chemical Atmospheres (NFPA 496, 497, 499)[*=1]Principal Member of API Subcommittee on Electrical Equipment (API RP500, and 505)[*=1]Several IEEE papers on classified loations.[*=1]Designed electrical systems for hazrdous locations (mostly refineries) over 40 years

 

[ritelec]

TY.

who's the man?

You are.

thanks again.
Rich

 

[Gregg Harris]

Answer is B

Class 1 division 2

 

[KentAT]

The answer for me is simple.
"under normal conditions..." is all I need to hear.

NEC 500.5(B)(1)(1) Class I, Division 1. A Class I, Division 1 location is a location
(1)In which ignitible concentrations of flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors can exist under normal operating conditions, or
...that's where the debate ends for me.


If is a normal condition when the flammable vapors can be present, it is a Div1. The intermittent nature doesn't matter. If I have venting controls for a process valve inside a building, and the controls use natural gas for the media, then it is a normal condition for the controls to exhaust/vent into the room. It was designed that way, accepted, and would need to have a Div 1 area surrounding the exhaust/vent port because the flammable vapor can be there under normal conditions.

To say it is a Div 2, which part of the NEC Div 2 qualifier could be used to substantiate the lesser hazardous rating of Div 2?

(NEC 500.5(B)(1)(2)) Class I, Division 2 location is a location
(1) In which volatile flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems or in case of abnormal operation of equipment, or

(2) In which ignitible concentrations of flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors are normally prevented by positive mechanical ventilation and which might become hazardous through failure or abnormal operation of the ventilating equipment, or


(3) That is adjacent to a Class I, Division 1 location, and to which ignitible concentrations of flammable gases, flammable liquid?produced vapors, or combustible liquid?produced vapors above their flash points might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.


(1) doesn't fit, because the test question clearly states the vapors can be present under normal operations. This Div2 definition specifically refers to the presence of those vapors are due to an "accidental rupture or breakdown" or "abnormal operation", neither of which are normal.

(2) doesn't fit, because the test question does not bring ventilation into the discussion.

(3) doesn't fit, because the test question (a) doesn't state that there is a Div 1 location adjacent to the area in question, and that those vapors that can be present are because of the adjacent Div1 area.

Therefore, based solely on the merits of the info we are told by the question, it clearly meets the Div1 description, and it does not clearly meet any of the criteria that allow us to reduce that to a Div2.

...my 2 cents anyway...

 

[Gregg Harris]

The answer for me is simple.
"under normal conditions..." is all I need to hear.

NEC 500.5(B)(1)(1) Class I, Division 1. A Class I, Division 1 location is a location
(1)In which ignitible concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors can exist under normal operating conditions, or
...that's where the debate ends for me.


If is a normal condition when the flammable vapors can be present, it is a Div1. The intermittent nature doesn't matter. If I have venting controls for a process valve inside a building, and the controls use natural gas for the media, then it is a normal condition for the controls to exhaust/vent into the room. It was designed that way, accepted, and would need to have a Div 1 area surrounding the exhaust/vent port because the flammable vapor can be there under normal conditions.

To say it is a Div 2, which part of the NEC Div 2 qualifier could be used to substantiate the lesser hazardous rating of Div 2?

(NEC 500.5(B)(1)(2)) Class I, Division 2 location is a location
(1) In which volatile flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems or in case of abnormal operation of equipment, or

(2) In which ignitible concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors are normally prevented by positive mechanical ventilation and which might become hazardous through failure or abnormal operation of the ventilating equipment, or


(3) That is adjacent to a Class I, Division 1 location, and to which ignitible concentrations of flammable gases, flammable liquid–produced vapors, or combustible liquid–produced vapors above their flash points might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.


(1) doesn't fit, because the test question clearly states the vapors can be present under normal operations. This Div2 definition specifically refers to the presence of those vapors are due to an "accidental rupture or breakdown" or "abnormal operation", neither of which are normal.

(2) doesn't fit, because the test question does not bring ventilation into the discussion.

(3) doesn't fit, because the test question (a) doesn't state that there is a Div 1 location adjacent to the area in question, and that those vapors that can be present are because of the adjacent Div1 area.

Therefore, based solely on the merits of the info we are told by the question, it clearly meets the Div1 description, and it does not clearly meet any of the criteria that allow us to reduce that to a Div2.

...my 2 cents anyway...

Division 1 the ignitable concentration of flammable gases, vapors or liquids can exist all of the time and is anticipated that they are there all of the time. A higher design safety factor must be in place.

Division II the ignitable concentration of flammable gases, vapors or liquids are not likely to be present but intermittently they can be. Lower design safety factor.


Try reading the question as a two separate parts; A location in which hazardous concentrations of flammable vapors exist intermittently is designated as

Division 1 ignitable concentration always anticipated to be present. Higher safety factor required.

Division 2 vapors should never be present, only under intermittent conditions. Lower safety factor required.


Both scenarios are under normal conditions; Division 1 anticipated to be there all of the time, Division 2 not anticipated to be present all of the time, except intermittently.