5 replies to this topic

[Araboni]

Dear Art
By referring to your spreadsheet named “Producing and maintaining vacuum” , attached to post http://www.cheresour...cuum#entry51027
, finally in page “Equipment sizing “ , in case of vacuum pump with vent condenser , you have given below data as the Vacuum pump suction spec:
Air seepage +water vapor flow: 35 Acfm
Vacuum Press 0.95 inHg (total press)
Temp : 25 ^OC
Do you mean that I shall order a Vacuum Pump with above flow, press and temp?
If so , I got confusion , as the amount of individual Air seepage by itself is 18.4 lb/h (calculated in page “Sizing Example Problem”) so that such an air seepage will have a volumetric flow rate of 131Acfm at above conditions, as per Dalton Law!! So shall I order a vacuum pump with this flow instead of 35Acfm??
In fact , I believe that if the Vacuum press at suction side of vacuum pump is the same 3.5 in Hg, the air +water vapor flow of 35 Acfm seems OK.
Could you please clarify?
Attached please find my comments.

Attached Files

•  questions on Art Montemayor Spreadsheet.xlsx   1.13MB   63 downloads

Edited by Araboni, 01 August 2012 - 05:57 AM.

[Art Montemayor]

Araboni:

I think your confusion is caused by a misplaced error in my calculations where I indicated I would be carrying out (3.5-.95). I subtracted the vapor pressure expressed in psia instead of inches Hg. This, of course carries over to other calculations. The corrections are shown in the attached Rev1.

In the future, please do not employ “Print Screen” copies on Excel. Simply use the original workbook, make your comments on it using text boxes, call outs, or comments and re-title the workbook with a continuing Rev number. Also, protect the worksheets so that your call outs or text boxes don’t “wander” and move within the worksheet. I haven’t been on the Forum because I had medical surgery and have been out of pocket, recovering. I had to copy your comments onto the original workbook because your comments and “Print Screen” objects were moved so your indicated comments were difficult to identify. All this takes time and that is why I am tardy. Correcting calculations and making new revision numbers are all part of an engineer’s career. You should learn that as soon as possible.

Thank you for your checking and identification of errors.

Attached Files

•  Producing and Maintaining Vacuum - Rev1.xls   201.5KB   177 downloads

[harshad katre]

Dear Sir,
The sheet is protected so the changes can not be made in the worksheet.
Also there is one correction in the vaccum pressure measurement showing 1 atmosphere = 101.325 pascals which should kilopascals OR 101,325 pascals.

Thanking You.

Regards,
Harshad Katre

[Araboni]

Dear Art
Thank you for prompt reply. As your worksheet is protected, I was not able to incorporate the pertinent comments thereon. Anyhow my final query still remains:
As you considered the worst case that is Pump vacuum suction press of 0.95 in Hg (taking into account the max 2.55 inHg press drop in vent condenser) , I believe that the gas flow rate entering pump shall also be recalculated based on this press as the total press, instead of 3.5 in Hg!!
Please kindly clarify

[foybanji]

Attention Mr Art Montemayor

 

Please i will like to request for the Excel Spreadsheet for vacuum relief valve sizing and the procedure. 

 

Many thaanks.

Regards

Segun

[Art Montemayor]

Segun:

 

All you have to do is click on the attached workbook in Post #2 and you will have the workbook.

 

I have deleted your email address; you don't want everyone in the world sending you thrash and viruses.