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paperdesk
August 12th, 2008, 03:21 PM
Hello! I'm proofreading for a magazine and we have a series of articles about SCUBA diving. The author abbreviated atmospheres as ATM, but I learned it as ATA. I'm wondering if ATM is also correct, or possibly even more correct? Any ideas?

Thanks!

Ted

Walter
August 12th, 2008, 03:25 PM
ATM or atm is atmosphere or atmospheres. ATA, ata or ATMA is atmospheres absolute. Both are correct, depending on what you want to say.

Sideband
August 12th, 2008, 03:27 PM
ATM is atmospheres, but ATA is atmospheres Absolute. In other words, 33' of water is 1 ATM of water but it is 2 ATA because of the 1 atmosphere of air above it.

paperdesk
August 12th, 2008, 03:27 PM
Hi Walter, thanks for the info. Here is what the article says: "At sea level, the pressure is 1 atmosphere (ATM). at 33 feet below the surface, the pressure is 2 ATM. at 66 feet, it is 3 ATM, and 99 feet it is 4 ATM."

Is that right, or should it say ATA?

roakey
August 12th, 2008, 03:28 PM
As Walter says, depends. If you're talking about relative pressure, it's ATM:

"For every 33 feet you decend, you increase the pressure by 1 ATM"

If you're talking about the total pressure, it's ATA:

"At 66 feet, you're subjected to 3 ATA of pressure".

Roak

[added on edit]

Race, you responded while I was posting. Though both are technically correct, I feel that "ATA" would be more correct in your case.

Roak

Walter
August 12th, 2008, 03:30 PM
Either is correct, has the concept of atmospheres absolute been introduced? If it has, use ATA, if it hasn't, use ATM. I would replace that w with an s.

nwhitney2003
August 12th, 2008, 03:31 PM
I'm wrong so I deleted my post

paperdesk
August 12th, 2008, 03:43 PM
So, IF I understand correctly, the article should list ATA not ATM? It doesn't really explain a lot more about the topic, it's not a technical article.

paperdesk
August 12th, 2008, 03:45 PM
I would replace that w with an s.

Good catch, do you need a job? You can work for us :)

Charlie99
August 12th, 2008, 03:47 PM
ATA is unambigous. It is atmospheres absolute.

ATM has some possiblity of confusion. Personally, when I use ATM I mean gauge pressure, with sea level atmosphere as the reference. In other words, at 33feet you have a pressure of 1ATM and 2ATA.

Not everybody uses that convention as the meaning of ATM, but everyone agrees that ATA is an absolute pressure, referenced to vacuum. If you use ATA you eliminate the confusion.

paperdesk
August 12th, 2008, 03:47 PM
Either is correct, has the concept of atmospheres absolute been introduced? If it has, use ATA, if it hasn't, use ATM. .


We are talking about total pressure, though it doesn't go into great depth (lol) on the topic.

Ted

TwoBitTxn
August 12th, 2008, 03:50 PM
If it's a non-technical article geared towards non divers most of your readers will not understand the difference between ATA and ATM. I think ATM shold be used. If the majority of the readers are divers, there is the possibility that ATA will be understood.

Naturally, any abbreviation should be defined before being used...

paperdesk
August 12th, 2008, 03:51 PM
ATA is unambigous. It is atmospheres absolute.

ATM has some possiblity of confusion. Personally, when I use ATM I mean gauge pressure, with sea level atmosphere as the reference. In other words, at 33feet you have a pressure of 1ATM and 2ATA.

Not everybody uses that convention as the meaning of ATM, but everyone agrees that ATA is an absolute pressure, referenced to vacuum. If you use ATA you eliminate the confusion.

Ok! That does make perfect sense. I'll change it to ATA.

Thank you all for your help! I'm sure I studies this when I got my c-card, but since then it's slipped into a dark place in my mind that I couldn't access . . . .

paperdesk
August 12th, 2008, 03:54 PM
If it's a non-technical article geared towards non divers most of your readers will not understand the difference between ATA and ATM. I think ATM shold be used. If the majority of the readers are divers, there is the possibility that ATA will be understood.

Naturally, any abbreviation should be defined before being used...

Ohhhhh. Just when I thought I had an answer . . .

300bar
August 12th, 2008, 03:54 PM
Just change the whole thing to BAR.Add 1 for atmosphere and your ready.:D

Walter
August 12th, 2008, 03:54 PM
If you're not explaining, I would spell it out - atmospheres absolute.

scubajcf
August 12th, 2008, 03:57 PM
Further referenced in the US Navy Dive Manual.

Click here to download version 6 - SEA 00C3 Diving Publications and Technical Documentation (http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9) or directly at http://www.supsalv.org/pdf/DiveMan_rev6.pdf

Chapter 2 Section 2-9(1) or pages 131 and 132

////

Doc Intrepid
August 12th, 2008, 03:59 PM
Just FWIW, I agree that if the article is intended to be read by divers, I would use ATA.

Since you must define either, ATA is a more frequently used variable when calculating mixed gas diving requirements and consumption in general.

JMHO,

Doc

paperdesk
August 12th, 2008, 04:08 PM
300Bar, I had the same temptation . . .

SCUBAjcf, I'm checking out the link.

How's this? Trying to keep it simple:

"At sea level, the pressure is 1 ATA (atmospheres absolute). At 33 feet below the surface, the pressure is 2 ATA." etc.

Doc Intrepid
August 12th, 2008, 04:12 PM
works for me! :D

300bar
August 12th, 2008, 04:15 PM
300Bar, I had the same temptation . . .Don't be tempted just show that the rest of the globe is metric:D

SCUBAjcf, I'm checking out the link.

How's this? Trying to keep it simple:

"At sea level, the pressure is 1 ATA (atmospheres absolute). At 33 feet below the surface, the pressure is 2 ATA." etc.You're absolutly right.But in the rest of the world we call it 10 meters/2bar.:rofl3:

.......

Air On
August 12th, 2008, 04:17 PM
Spell it out and not be cute with Anachronisms, closing the door to people debating over stupid things.

paperdesk
August 12th, 2008, 04:23 PM
Spell it out and not be cute with Anachronisms, closing the door to people debating over stupid things.

I'll try to avoid anachronism's in the future . . .

Main Entry: anach·ro·nism
Pronunciation: \ə-ˈna-krə-ˌni-zəm\
Function: noun
Etymology: probably from Middle Greek anachronismos, from anachronizesthai to be an anachronism, from Late Greek anachronizein to be late, from Greek ana- + chronos time
Date: 1617
1: an error in chronology; especially : a chronological misplacing of persons, events, objects, or customs in regard to each other
2: a person or a thing that is chronologically out of place; especially : one from a former age that is incongruous in the present
3: the state or condition of being chronologically out of place

paperdesk
August 12th, 2008, 04:27 PM
.......

Cool, you're a :dork2: diver! I have to find out if they'll let me join the ranks even though I'm a NMOF'er.

Ted

CardShark
August 12th, 2008, 04:31 PM
How many times will the proposed TLA be utilised in the article ? If few, perhaps you'd be better served to write "atmospheres" ?

300bar
August 12th, 2008, 04:33 PM
Cool, you're a :dork2: diver! I have to find out if they'll let me join the ranks even though I'm a NMOF'er.

Ted

All are welcome at the DorkDiver ranks,as long as you have fun diving.:D


I'll try to avoid anachronism's in the future . . .

Main Entry: anach·ro·nism
Pronunciation: \ə-ˈna-krə-ˌni-zəm\
Function: noun
Etymology: probably from Middle Greek anachronismos, from anachronizesthai to be an anachronism, from Late Greek anachronizein to be late, from Greek ana- + chronos time
Date: 1617
1: an error in chronology; especially : a chronological misplacing of persons, events, objects, or customs in regard to each other
2: a person or a thing that is chronologically out of place; especially : one from a former age that is incongruous in the present
3: the state or condition of being chronologically out of place

Guess this shows you might be a real DorkDiver.:rofl3:

paperdesk
August 12th, 2008, 06:14 PM
All are welcome at the DorkDiver ranks,as long as you have fun diving.:D

Guess this shows you might be a real DorkDiver.:rofl3:

I like you :D DorkDivers at the best.

BTW, I know a lot of Dutch divers, but do you dive at home?? I always find you guys in Mexico, Philippines, South Africa etc. Do you dive at home too? My ancestors came from the Netherlands, and I have many relatives there about.

Ted

roakey
August 12th, 2008, 06:45 PM
Just change the whole thing to BAR.Add 1 for atmosphere and your ready.:D
Of course 1 BAR does not equal 1 ATM, adding to the confusion.

Roak

300bar
August 12th, 2008, 07:01 PM
I like you :D DorkDivers at the best.

BTW, I know a lot of Dutch divers, but do you dive at home?? I always find you guys in Mexico, Philippines, South Africa etc. Do you dive at home too? My ancestors came from the Netherlands, and I have many relatives there about.

Ted

Not to be bragging :D but the Netherlands are most likely to be the country with the most dives per year.Well we atleast count them.:mooner:
Example.1 Zeeland,southern(coastal) province(52 divesites) has a anual # of dives per year of 1.000.000 :11:
Example.2 Lake Oostvoorne (a training lake)(3 divesites) has a anual # of 600.000 dives per year.:11: No figures on the rest of the lakes (YET):D.
It is estimated that 10% of the Dutch have a diving C-Card.:11:

2nd bragg.:D We're most likely the most well traveled nation on the Globe.As you said, you can find us anywhere on this planet.Like it or not.:rofl3:

Hey Ted where is the family located?And do they dive.:D

300bar
August 12th, 2008, 07:04 PM
Of course 1 BAR does not equal 1 ATM, adding to the confusion.

Roak

Scientificly you're correct,but for scuba the difference is so small we can ignore it.:D

paperdesk
August 12th, 2008, 07:05 PM
Oh no roak, it's just evil to bring that into it ;)

300bar: Wow, I didn't know that the Dutch were such prolific divers! Pretty cool.

300bar
August 12th, 2008, 07:16 PM
300bar: Wow, I didn't know that the Dutch were such prolific divers! Pretty cool.

Just come on over,and we'll show you.:D
Dont know IF you speak or read any Dutch,but just click the link and read the # in the 2nd line.:D
http://www.natuurlijkoostvoornsemeer.nl/?fId=18
Just have a look at the(round)pics on the right.:)

Charlie99
August 12th, 2008, 07:19 PM
Of course 1 BAR does not equal 1 ATM, adding to the confusion.

RoakFurther adding to the confusion, 10msw (meters saltwater) is usually defined to be equal to 1 bar, not to 1atm. While this means that bar to msw conversion is just moving a decimal point, 10msw is NOT exactly equal to 33 fsw (They differ by 1.325% since 1atm is 1013.25 millibar, not 1000 millibar)

300bar
August 12th, 2008, 07:29 PM
(They differ by 1.325% since 1atm is 1013.25 millibar, not 1000 millibar)

As I said not interesting for scuba uses.:D

paperdesk
August 12th, 2008, 07:53 PM
As I said not interesting for scuba uses.:D

It's a little bit interesting to me, but I work in feet and lbs and now ata anyway . . .

300bar, As far as I know none of my South African (Afrikans) or Dutch family dive. Soo sad. I see your sig says Evert. Is that your given name? That's my family name! Not Everett, or Everet as most Americans want to spell it.

Ted

300bar
August 12th, 2008, 08:26 PM
It's a little bit interesting to me, but I work in feet and lbs and now ata anyway . . .

300bar, As far as I know none of my South African (Afrikans) or Dutch family dive. Soo sad. I see your sig says Evert. Is that your given name? That's my family name! Not Everett, or Everet as most Americans want to spell it.

Ted

Ted,

That is my given/first/christian name.So sorry no family.:(
As for the Americans,most can't even spell my name correct in a PM.:rofl3:
It's Evret or Evart or Everett and then some more.:rofl3:
Most call me ED when we meat.:D
btw we had/have some family in South Africa somewhere around Cape Town.

Evert.

roakey
August 13th, 2008, 11:33 AM
Scientificly you're correct,but for scuba the difference is so small we can ignore it.:D
In the case we're talking about, yes. But when we start talking about cylinder pressures, it adds up. So I prefer not to muddy the waters to begin with (google "The Law of Primacy" as it relates to education).

Roak

Ps. Personally, I want a depth gauge that reads in atmospheres (or BAR, since for depth as you mention it does't matter) so I can drop all the depth conversions! :)

Charlie99
August 13th, 2008, 11:44 AM
Ps. Personally, I want a depth gauge that reads in atmospheres (or BAR, since for depth as you mention it does't matter) so I can drop all the depth conversions! :)Depth in meters comes pretty darn close to being depth in bar --- just drop a decimal place. It's a lot easier to just drop a decimal place than is is to divide by 33.

BTW, the easy way to divide by 33 is to multiply by 3, and then drop 2 decimal places.

For example, 50' x 3 =150. Divide by 10 to get 15 meters, divide by another 10 to get = approx. 1.5atm ....... or 2.5ata or 2.5bar absolute.:D

paperdesk
August 13th, 2008, 12:29 PM
Depth in meters comes pretty darn close to being depth in bar --- just drop a decimal place. It's a lot easier to just drop a decimal place than is is to divide by 33.

BTW, the easy way to divide by 33 is to multiply by 3, and then drop 2 decimal places.

For example, 50' x 3 =150. Divide by 10 to get 15 meters, divide by another 10 to get = approx. 1.5atm ....... or 2.5ata or 2.5bar absolute.:D

I'm intrigued by all this. Being strictly a recreational diver, and not having even taken a Nitrox course I haven't really thought about things in this light. It's all very interesting though! Thanks for sharing.

Ted

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