ATA vs ATM which is right? Need to know for magazine.

paperdesk

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• Aug 12, 2008

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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

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• Aug 12, 2008

• #2

ATM or atm is atmosphere or atmospheres. ATA, ata or ATMA is atmospheres absolute. Both are correct, depending on what you want to say.

 

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• #3

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.

 

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paperdesk

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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?

 

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roakey

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• #5

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

 

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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

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I'm wrong so I deleted my post

 

Last edited: Aug 12, 2008

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paperdesk

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• #8

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.

 

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paperdesk

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Walter:

I would replace that w with an s.

Click to expand...

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

 

Charlie99

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• Aug 12, 2008

• #10

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.