11 replies to this topic

[Padmakar Katre]

Hello friends This is my pleasure to give a online calculations of antoine coefficients based vapor pressure dat on Excel please it is really helpful

[latexman]

Sweet! Thanks!

[Suryakant Randeri]

Dear Mr. Padmakar,
I am not able to open and read your report on line (design/calculation Excel sheet) on " The calculation of antoine coefficient based vapor pressure data Excell sheet.

can you mail it to me once again at my email address: randeri@hpfl_india.com with copy to scranderi@yahoo.co.in ?

regards,

Surya Randeri

[JEBradley]

I couldn't download it either - not sure where the link is or where I have to go to get it. Would be a very useful thing to have though.

[Suryakant Randeri]

Dear Mr. Padmakar,
I am not able to open and read your report on line (design/calculation Excel sheet) on " The calculation of antoine coefficient based vapor pressure data Excell sheet.

can you mail it to me once again at my email address: randeri@hpfl_india.com with copy to scranderi@yahoo.co.in ?

regards,

Surya Randeri

Dear Mr. Bradley,
Mr. Padmaker has sent me a copy of the excel sheet for VP by Antoine
I would like to attach the same file for your quick reference once again
good luck

Surya Randeri

Attached Files

•  VP_Using_Antonie_Coefficient.xls   204.5KB   954 downloads

[MrShorty]

Interesting.

One main complaint. There is no documentation with the antoine constants. In my experience with the vapor pressure literature, there is a lot of bad data out there. Without knowing where the Antoine constants came from or the data on which those constants are based, the calculator becomes less useful

For interest, I compared your calculator to a few compounds in DIPPR. In many cases agreement with DIPPR was good. In other cases, agreement was poor. That's not to say that DIPPR is the last word in vapor pressures, but at least I can look up where DIPPR got their data for the correlation and evaluate whether I believe they had a good source or not.

With that in mind, this becomes an interesting exercise in Excel programming that could be useful as an educational tool or to get an idea of what the vapor pressure might be. But I wouldn't use it for anything that I needed to rely on or document.

A couple of other comments.

In scanning the database, I see several compounds for which the constants are 0,0,0. Obviously those aren't correct Antoint constants, and hopefully the users will be smart enough to recognize when those cases arise. I also noted a few compounds (1-hexadecene for example) where the tabulated Antoine constants are completely unreasonable and yield completely unreasonable values for the vapor pressure. Again, as long as users can recognize the garbage, it's ok. My mentor used to worry that engineers today were too prone to treat computers as "magic black boxes" that take our input, spit out an answer, and we accept the result without any further evaluation or thought.

I would also point out that the Antoine equation is generally considered to be limited to a pressure range up to about 2 atm. Above that pressure, the equation is incapable of properly representing a vapor pressure curve. It should also be noted that the Antoine equation is generally considered to be a purely empirical correlation, and can have difficulty extrapolating beyond the limits of the data on which it is based. I notice that the database has columns for min and max T, it might be useful to program the output section to report those values so a user can quickly see if a desired temperature is outside the range of applicability.

Hopefully that's not too negative of a post. It is an interesting tool that can be useful when used properly with an appropriate amount of skepticism regarding the generated vapor pressures.

[Art Montemayor]

I repeat with my thanks to Padmakar. I failed to look at the spreadsheet when it was first posted at the start of the year because it fell prey to a series of computer hacker raids we experienced on the Forums.

Now that I’ve had a chance to download a copy and look at the product, I am reminded of a lot of the pertinent and important points that Shorty rightfully brings out.

No one should look a gift horse in the mouth. However, as Shorty points out, this horse may not be able to finish the race. We don’t have its pedigree – or even a hint as to who sired him. Like just about all other Chemical Engineers, I collect Vapor Pressure data whenever and wherever I find it. However, before I can use it, I must have some documentation that identifies its origin or its lineage. And I’m sure we professionals on this Forum know that fully well.

However, I commend Shorty for sharing his experience and expert advice on what this type of data represents to a practicing engineer. I also share in his same experiences. I would add that Antoine vapor pressures are acknowledged as not only being limited – as Shorty points out – to a pressure range up to about 2 atm, but I have also found the relationship to be sensitive to the methodology of obtaining the original data and the method(s) of extrapolation. I’ve even seen some authors transmitting the data with the wrong units attached to it. Additionally, some compounds do not lend themselves to good representation via the Antoine type of curve. I’ve taken empirical data and found that I can regress it with a much more accurate curve type than the Antoine version. That’s is precisely why it is so important to have documented referenced data when one is tempted to use it in a calculation.

I write this among ourselves because I know that somewhere behind the scenes there are always some eager and bright students – and, yes, some young grads – looking over our shoulders and who will jump on this information as heaven-sent. I hope they read this thread very carefully and take it with a grain of salt.

Nevertheless, Antoine coefficients are the darlings of the research and development labs. This is an area where they come in as real useful because of their simplicity and availability. As Shorty says, when you need an estimate or an idea of the magnitude of the expected pressure, they are very handy to have.

[gvdlans]

A little bit of research showed me that the source data used in Padmakar's spreadsheet (cells B1048:AE1515) is identical to the table that can be downloaded from the cheresources website ( http://www.cheresources.com/data.xls ). I have the impression that this table is largely based on the Property Databank that is included as Appendix A of the book "The Properties of Gases & Liquids" by Reid, Prausnitz and Poling.

The Parameters in the Antoine Equation have almost certainly been taken from Appendix D of Coulson and Richardson's Chemical Engineering Volume 6 (2nd edition), that has indeed been based on the above mentioned book "The Properties of Gases & Liquids".

[AllyK]

Is there a way to calculate antoine constants? I have been having trouble for quite some time finding antoine constants and have come to the conclusion there may be none for my components. I have heard of a group contribution method to find vapour pressures and have searched via the internet but i have had trouble understanding what to do. Any pointers anyone?

[kkala]

Concerning post No 9, you can look at Perry's Chemical Engineers' handbook, Physical and Chemical data, Prediction and correlation of physical properties.
In 7th edition, two prediction methods are presented for pure hydrocarbons (single components, not mixtures), if critical pressure and temperature or sg and normal boiling point are known. And one method for non hydrocarbon organics. These may not be group contribution methods (like e.g. parachor for viscosity estimates, http://encyclopedia2.thefreedictionary.com/Parachor), yet they might help.

Edited by kkala, 14 May 2012 - 04:37 PM.

[silvianabochum]

I have concerned to use 5 Antoine contants according to DIPPR equation. Could anyone kind help to send me these five Antoine constants for CO2 and acetic anhydride?

 

I am deeply hoping for greatful help.

 

Thank you in advance,

 

Warm regards

[breizh]

Hi ,

 Consider these resources.

 

Hope this helps

 

Breizh

Edited by breizh, 13 October 2013 - 08:30 PM.