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Romel
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Join Date: Nov 2011
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Acceptable Value for Atmospheric Pressure?

01/07/2013 9:20 AM

I was told by my professor that in practice, engineers rounded off the value of atmospheric pressure to 100 kPa. I just want to know if this value is really acceptable to wide range of applications. What are these applications that aren't so critical with the difference of 1.325 kPa? Thanks.
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Pathfinder Tags: 100 kPa 101.325 kPa atmospheric pressure
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lyn
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#1

Re: Acceptable value for atmospheric pressure?

01/07/2013 9:37 AM

We're not using slide rules any more.

Use the correct figure. Your calculator won't care.
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PWSlack
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#2

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 10:23 AM

Well, doesn't it depend on the weather? Highs? Lows? That sort of thing?

One of the biggest faux pas that can be made in the process industries is to use an absolute pressure transmitter for a level measurement in a shallow vessel. Fill to the same level pressure one day and there will be a different volume in the vessel to that on the day before.

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Tornado
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#3

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 10:37 AM

Altitude also.

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lyn
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#4

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 10:57 AM

I think OP is talking about a: standard atmosphere.
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Romel
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Join Date: Nov 2011
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#8
In reply to #4

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 12:53 AM

Thanks lyn. The link you provide helps a lot. I already forget that bar thing. Now I know... LOL.
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Fredski
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#5

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 11:27 AM

I use 14.7 gauge pressure myself, whatever works for you...depending on your altitude
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lyn
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#6
In reply to #5

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 12:18 PM

I have a bad altitude, so my pressure's higher.
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Fredski
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#7
In reply to #6

Re: Acceptable Value for Atmospheric Pressure?

01/07/2013 12:21 PM

did you just admit to being high????
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lyn
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#13
In reply to #7

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 9:23 AM

I'm high on life!
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Romel
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#9
In reply to #5

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 12:57 AM

Are you still using the English system for applications? I am curious how wide is the coverage of that system this day.
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dhayanandhan
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#10

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 4:22 AM

Dear Romel,

It is 103 kPa. is one Atmosphere - which is 14.696 psi., or 1.03 Kg/cm^2 at NTP CONDITIONS.

For higher altitudes - correction factor is to be applied. I studied in FPS System and PASCALS came later.

DHAYANANDHAN.S
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Romel
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#11
In reply to #10

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 5:14 AM

Sir dhayanandhan, I think that value is too high. As far as I can recall one atmosphere is 101.325 kPa both in NTP and STP.

In our educational system (Philippines), we are trained to both SI and English system of units. Although English system is drastically declining in licensure examinations, we cannot easily eliminate it from our system because of the great influence of US. That is why I am very curious if how strong is English system in the US for now. I am seeing new textbooks from US universities written in SI which indicates the end of that system, but I still wondering how wide and how deep it goes in the field. I hope somebody will share.
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dhayanandhan
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#12
In reply to #11

Re: Acceptable Value for Atmospheric Pressure?

01/08/2013 9:02 AM

Dear Mr.Romel,

You are right. I It is 101.325., kPa is One atmospheric pressure of 14.696 psi or 1.3 Kg//cm^2.

I studied in FPS SYSTEM, and later, I tried to collect data on Pascals, Newton etc. It is only faint memory.

You can find the conversion at the link

http://www.unitjuggler.com/convert-pressure-from-kPa-to-psi.html and here,

https://www.google.co.in/search?hl=en&newwindow=1&tbo=d&site=&source=hp&q=*conversion+kPa+to+psi*&oq=*conversion+kPa+to+psi*&gs_l=hp.3..0i30l2j0i5i30l7j0i8i30.7289.24025.0.27714.23.23.0.0.0.0.489.2398.2-9j0j1.10.0.les%3B..0.0...1c.1.6Na36dk8WZo

Thanks for your correction.

DHAYANANDHAN.S
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