Normal vs. Standard

[zdas04]

I had a plant guy tell me today that "Nm3" referred to a Universal Standard that was the same everywhere in the world (101.35 kPaa and 0C) and that "Standard" conditions was term that could only be applied to cubic feet and could never be applied to metric volumes. A quick search showed 20 different pressure/temperature combinations for "normal", and at least that many references to "Standard Cubic Meters". Does anyone have a feel for where the "Normal" vs. "Standard" terminology came from? I was under the impression that "Normal" was a plant convention that was defined for each plant (kind of an insider's speak), but this guy was very offended at that idea.

I don't care what terminology an individual uses, I can usually communicate on his terms, but this got emotional and I'm trying to get my head around why.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[IRstuff]

some people are are just like that

TTFN
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[Eltron]

In my opinion, the term normal applies to an average which implies some allowable variation. Whereas a standard is something that should not vary.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[MintJulep]

How do you cube a unit of torque?

101.35kpa absolute is "normal" atmospheric pressure at at "mean" sea level.

"Normal" atmospheric pressure is the theoretical pressure of "dry air" - which never exists in nature.

I recall a "what is sea level" discussion thread, but I can't find it now. But I think I recall that it's an arbitrarily defined surface.

0C is the freezing point of an arbitrary substance at "normal" atmospheric pressure.

So basically "Normal" or "Standard" is based on the properties of an arbitrary substance resting on an arbitrary surface under atmospheric conditions that never exist.

 

[msquared48]

David:

Face it. It s just standard that the guy is not normal.

Just forget it and move on.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[Latexman]

I definitely did not get the e-mail on this "Universal Standard". Unfortunately, we are at the mercy of semantics on this one.

Good luck,
Latexman

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[VEBill]

"I had a plant guy tell me today that 'Nm3' referred to a Universal Standard that was the same everywhere in the world (101.35 kPaa and 0C)..."

Unless it's 101.32500 kilopascals. Ref.

http://www.oxywise.com/en/news/What_is_the_difference_between_Nm3_and_Sm3

It only takes a single counter-example to prove that it's not a "Universal" standard. Assuming that you're arguing with a reasonable person.

One should probably price gases in moles. LOL.

 

[zdas04]

MintJulep,
The first time I saw that terminology it was in an e-mail from a person who was without a clue about oh so many things. I actually asked him in all seriousness if he was cubing a Newton-meter or if he was multiplying a force times a volume which I couldn't get my head around. Of course he got huffy.

The guy yesterday had just spent a full day going through a 200 page document and changing SCM to Nm3 and was quite proud of himself for catching my irrational terminology. I told him that I could successfully accomplish gas production using cubic furlongs at 6000K and 2200 psia as long as all the terms were explicitly defined and used consistently (even if the temperature and pressure were impossible, since "standards" put us into an imaginary realm where physical things don't matter--if you doubt that, calculate velocity in a 1000 barg line running at 60C and then recalculate it at STP, different universe and only one of these numbers relates to physical phenomena.

VEBill,
Moles make holes in they yard, no one like moles. People would have priced gases in mass units if there was any agreement on the EOS used to calculate density. I consulted for an API committee 20 years ago where they spent a year trying to define density mathematically for inclusion in the measurement standard because they were actually proposing changing the standard from Standard Volume to Mass. Thankfully money ran out for that project and we evolved into using a combination of volume and energy, both of which can be adequately defined to most everyone's satisfaction.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[MintJulep]

According to "The Internet"

Sm3/hr -Standard cubic meters per hour, measured at standard metric conditions( 1 Atm & 15 °C). Used primarily in Canada, South America, and New Zealand
Nm3/hr -Normal cubic meters per hour, measured at normal metric conditions (1 Atm & 0 °C). Used primarily in Europe.

So if he only changed the units, and didn't change the numbers then he made everything wrong.

 

[TD2K]

I seem to recall from high school that 'normal' in the SI system was defined as 0 deg C and 101.325 kPa as MJ quoted but I'm sure there are other industries that have their own definition of "normal".

I've enjoyed your rants/disserations (pick which one you like) Dave about how 'standard conditions' are anything but that. I've been in meetings where people have been throwing about 'standard' and I've asked what are the "standard conditions" only to be pooh poohed as 'everyone knows what that is' so I'll proposed 60F and 14.695 psia and usually the fight is on .

Not as bad as clients who want to use cfm and scfm for air compressor ratings interchangeably when you are sitting at 6,000 feet elevation.

 

[VEBill]

All that I recall is PV=nRT.

 

[IRstuff]

"So if he only changed the units, and didn't change the numbers then he made everything wrong."

Unless he made it better for himself, economically...

TTFN
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[zdas04]

VE1Bill,
Don't tell Redlich-Kwong that, their EOS has a dozen extra terms.

TD2K
I do tend to rant about "standard" being "whatever the parties to an agreement set down in their contract". I have a question like that on my course pre-test an no one has ever gotten it right--many students have come back to me angry that their pet 14.696 psia at 60F (or 14.73 at 60F or or 14.7 psia at 60F or 101.325 kPaa at 0C) was not the right answer. I have a slide in the course of all of the "standards" I've been able to find. The font is getting pretty small.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[stevenal]

We used STP in high school chemistry.

http://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure

 

[IRstuff]

and if you read the first paragraph of the article:

"The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted standards. "

Not very "standard" if there are two competing "standards," and even those two are not accepted by everyone.

TTFN
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[VEBill]

Old truth: "The nice thing about 'Standards' is that there are so many from which to choose."

 

[Ron]

David...I would tend to agree with your assessment that "normal" is a localized condition, whereas a "standard" would be something established across applications that are not necessarily localized.

With that in mind, a "standard" could become a "normality", but not necessarily the other way around.

Norms can be variable...standards not so much.

 

[zdas04]

Linguistically I agree with you, but in practice VE1BILL has it right. When I get asked to review a gas sales and processing contract (several times a year) the very first thing I do is look for a definition of "Standard". I don't care what the value is (and I see a very wide range of values), I just want to be certain that it is defined within the contract.

I saw a contract last year that said "Standard cubic feet will be calculated based on the values published by the Wyoming Government". First the sales were taking place in New Mexico. Second, there are 4 agencies in Wyoming that each have a definition, and there is no requirement within the state statutes that they use the same one (I found this out when I had to prepare some data under Wyoming DEQ rules that used 14.696 paia and 68F while the "raw" data came from the OCD who was using 14.73 psia and 60F). I also saw an RTU last week that had standard or "base" conditions hard coded as 14.6 psia and 78F--no idea where that came from, and people using that calculation would unknowingly violate several state and federal statutes and most contracts.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.