Ask The Brewmasters

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

I've found using 2.5xDO = TPO is a good calculation. We've verified this with units that measure TPO and DO. 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Jacquelyn,

For that calculation do you use a shaken or unshaken DO number?

I've found using 2.5xDO = TPO is a good calculation. We've verified this with units that measure TPO and DO. 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Ian, 

I believe the number used in that calculation would have to be a shaken number, it also assumes that you have a perfect fill with ~15ml headspace on a 12 oz can.  Over filled cans will have a lower ratio - ie. 363ml beer in can might be 1.5x shaken DO = TPO and under fills at ~348ml might be 3x shaken DO = TPO.  You might be able to apply a sliding scale based on your package weights. 

------------------------------
Brendan McGinn
MBAA District Great Plains Technical Committee
Director Of Brewing Operations
Zipline Brewing Co.
Lincoln, NE
(402) 937-1994

Original Message:
Sent: 02-27-2024 19:46
From: Ian Savage
Subject: TPO calculation method

Hi Jacquelyn,

For that calculation do you use a shaken or unshaken DO number?

I've found using 2.5xDO = TPO is a good calculation. We've verified this with units that measure TPO and DO. 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Kelly, 

a difference of 2.5xhigher TPO value using the Uhlig formula is unexplainable. 

Try to use the following formula: 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Kelly, 

a difference of 2.5xhigher TPO value using the Uhlig formula is unexplainable. 

Try to use the following formula: 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Everyone.

Question - When using this formula, will I need a +$1.5K Can Shaker before piercing my can off the line? Or, can I pull the can from the line, then pierce?

Also, where would DO's taken of the beer pre-filtration, post-filtration, and pre-canning fit in? We're collecting this data, and I want to make sure it is valuable outside of tighten practices pre- and post-filtration to control DO.

Thank you.

Hi Kelly, 

a difference of 2.5xhigher TPO value using the Uhlig formula is unexplainable. 

Try to use the following formula: 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Everyone.

Question - When using this formula, will I need a +$1.5K Can Shaker before piercing my can off the line? Or, can I pull the can from the line, then pierce?

Also, where would DO's taken of the beer pre-filtration, post-filtration, and pre-canning fit in? We're collecting this data, and I want to make sure it is valuable outside of tighten practices pre- and post-filtration to control DO.

Thank you.

Hi Kelly, 

a difference of 2.5xhigher TPO value using the Uhlig formula is unexplainable. 

Try to use the following formula: 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hi Everyone.

Question - When using this formula, will I need a +$1.5K Can Shaker before piercing my can off the line? Or, can I pull the can from the line, then pierce?

Also, where would DO's taken of the beer pre-filtration, post-filtration, and pre-canning fit in? We're collecting this data, and I want to make sure it is valuable outside of tighten practices pre- and post-filtration to control DO.

Thank you.

Hi Kelly, 

a difference of 2.5xhigher TPO value using the Uhlig formula is unexplainable. 

Try to use the following formula: 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

The "Uhlig Formula" is essentially an application of Henry's Law. There are several errors in the paper: Vilacha C, Uhlig K. 1985. Brauwelt International 1: 70-77 that make it hard to understand. The factor of 1.0332 in the denominator is the conversion from bar to atm. It should be 1.01325. I can't vouch for the accuracy of the polynomial:

4.17E-7*T^2+2E-4*T-0.0701. I am chasing down the original data.

Some oxygen analyzers now take separate measurements of HSO and DO. Shaking the package and using Henry's law would then be unnecessary. The results would be more accurate. 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------

Roger,

I agree that the equation is poorly explained and does not offer support for the polynomial or coefficients.  The equation offered by Daniela certainly agrees with TPO calculation spreadsheets available, but why it is so different from the widely available Uhlig form bothers me.

The "Uhlig Formula" is essentially an application of Henry's Law. There are several errors in the paper: Vilacha C, Uhlig K. 1985. Brauwelt International 1: 70-77 that make it hard to understand. The factor of 1.0332 in the denominator is the conversion from bar to atm. It should be 1.01325. I can't vouch for the accuracy of the polynomial:

4.17E-7*T^2+2E-4*T-0.0701. I am chasing down the original data.

Some oxygen analyzers now take separate measurements of HSO and DO. Shaking the package and using Henry's law would then be unnecessary. The results would be more accurate. 

Hello Community,

We have recently started taking a much closer look at DO levels off the packaging line with the goal of tracking and setting control limits for TPO values in cans.  For calculating TPO I have seen two methods:

The Henry's Law based spreadsheet calculators from Hach, etc.

The Uhlig Equation manually entered in Excel

These two calculations give me very different TPO results, with the Uhlig method giving results about 2.5X higher than the Henry's Law method. Those that calculate TPO, which calculation method do you use? Have you compared the two methods? Did your calculations match?

I've included the Uhlig equation and a few lines of TPO calculations showing the difference.

Uhlig Equation: TPO=DO((32*1000*HS(4.17E-7*T^2+2E-4*T-0.0701))/(0.082*T*1.0332*100)+1)

------------------------------
Kelly White
Country Boy Brewing
Georgetown KY
------------------------------