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. 

------------------------------
Jacquelyn Nelson
Quality Assurance
Deschutes Brewery
Bend OR
(503) 442-7611
------------------------------

Hi Jacquelyn,

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

------------------------------
Ian Savage
Crux Fermentation Project
Bend OR
(970) 306-3645
------------------------------

Original Message:
Sent: 01-18-2024 12:44
From: Jacquelyn Nelson
Subject: TPO calculation method

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

------------------------------
Jacquelyn Nelson
Quality Assurance
Deschutes Brewery
Bend OR
(503) 442-7611
------------------------------

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?

------------------------------
Ian Savage
Crux Fermentation Project
Bend OR
(970) 306-3645
------------------------------


Original Message:
Sent: 01-18-2024 12:44
From: Jacquelyn Nelson
Subject: TPO calculation method

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

------------------------------
Jacquelyn Nelson
Quality Assurance
Deschutes Brewery
Bend OR
(503) 442-7611

The formula TPO = (some number) x DO is not at all general. The (some number) varies a lot with temperature and headspace ratio (Vhs/Vbeer). 

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA
------------------------------

Original Message:
Sent: 02-28-2024 13:57
From: Brendan McGinn
Subject: TPO calculation method

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?

------------------------------
Ian Savage
Crux Fermentation Project
Bend OR
(970) 306-3645


Original Message:
Sent: 01-18-2024 12:44
From: Jacquelyn Nelson
Subject: TPO calculation method

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

------------------------------
Jacquelyn Nelson
Quality Assurance
Deschutes Brewery
Bend OR
(503) 442-7611

Kelly,

It is jay @bevalytic.com.... BTW, the file is here

:-)

J

------------------------------
Jorgen Skovbjerg
Anton Paar
Angwin CA
(831) 630-3020
------------------------------

Hi Kelly, 

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

Try to use the following formula: 

------------------------------
Daniela El Alam

------------------------------

Daniela,

Thanks for sharing this version of the equation, now my numbers match! I'm still not sure where some of the constants came from in the equation I was using, but it was the form I saw used in two different sources which did not separate out the headspace to liquid volume ratio.

I thought the haffman's formula was also Uhlig based, unless it is calculated differently between instruments since the Gehaltemeter doesn't measure the headspace O2 like the Total Package Analyzer does.

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

Original Message:
Sent: 01-19-2024 04:51
From: Daniela El Alam
Subject: TPO calculation method

Hi Kelly, 

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

Try to use the following formula: 

Vvl= volume liquid

Vhs= volume head space

Do the comparison again and look at what are the results. 

With the Haffmans TPO device you can perform investigations/comparisons of your canister oxygen results and perform some improvement tests on your lines if needed. Using the Haffmans formula you can have the HSO and DO values separately and you can also choose to compare the TPO results by making some measurements using the Uhlig formula.

Best Luck, 

------------------------------
Daniela El Alam

------------------------------

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.

------------------------------
Andrew Johnston
Production Brewery Manager
First State Brewing Co
Middletown DE
(302) 893-9005
------------------------------

Original Message:
Sent: 01-19-2024 04:51
From: Daniela El Alam
Subject: TPO calculation method

Hi Kelly, 

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

Try to use the following formula: 

Vvl= volume liquid

Vhs= volume head space

Do the comparison again and look at what are the results. 

With the Haffmans TPO device you can perform investigations/comparisons of your canister oxygen results and perform some improvement tests on your lines if needed. Using the Haffmans formula you can have the HSO and DO values separately and you can also choose to compare the TPO results by making some measurements using the Uhlig formula.

Best Luck, 

------------------------------
Daniela El Alam

------------------------------

Paint shaker: $150 plus some creative use of bunjee and duct tape. Yes, to get TPO you need both dissolved and headspace oxygen. The equation depends on Henry's law, which only works when the oxygen is at equilibrium between the liquid and gas phase, a condition brought about by shaking. The alternative is a sensor the analyzes DO and HSO independently. Could be costly, but more accurate than the equation.

Prior to packaging you are only interested in dissolved oxygen; headspace oxygen does not come into it. You would need a reliable way to grab a sample that completely fills the cavity of the analyzer without exposure to air. In-line analyzers would be ideal, obviating the need for samples.

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA
------------------------------

Original Message:
Sent: 02-14-2024 17:39
From: Andrew Johnston
Subject: TPO calculation method

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.

------------------------------
Andrew Johnston
Production Brewery Manager
First State Brewing Co
Middletown DE
(302) 893-9005
------------------------------


Original Message:
Sent: 01-19-2024 04:51
From: Daniela El Alam
Subject: TPO calculation method

Hi Kelly, 

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

Try to use the following formula: 

Vvl= volume liquid

Vhs= volume head space

Do the comparison again and look at what are the results. 

With the Haffmans TPO device you can perform investigations/comparisons of your canister oxygen results and perform some improvement tests on your lines if needed. Using the Haffmans formula you can have the HSO and DO values separately and you can also choose to compare the TPO results by making some measurements using the Uhlig formula.

Best Luck, 

------------------------------
Daniela El Alam

Andrew,

I use a $150 paint can shaker and place the cans in a cardboard box with foam inserts designed to ship beer (whalepod).  At first I measured both shaken and unshaken cans to compare, but have dialed it back to only shaken cans.  I test 6 cans per packaging run and if I see high DOs I can test a few unshaken cans to pinpoint oxygen ingress (headspace or liquid pickup). 

I also check DO around the centrifuge and caught that our newly installed fuge was the source of huge DO pickup.  We were able to adjust some settings after a bit of back and forth with the centrifuge servicing company and now see very little pickup across this transfer.  The DO in the bright tank is checked again the morning of packaging, this is what I compare my can DO numbers to.  

Hope this helps!

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

Original Message:
Sent: 02-14-2024 17:39
From: Andrew Johnston
Subject: TPO calculation method

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.

------------------------------
Andrew Johnston
Production Brewery Manager
First State Brewing Co
Middletown DE
(302) 893-9005
------------------------------


Original Message:
Sent: 01-19-2024 04:51
From: Daniela El Alam
Subject: TPO calculation method

Hi Kelly, 

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

Try to use the following formula: 

Vvl= volume liquid

Vhs= volume head space

Do the comparison again and look at what are the results. 

With the Haffmans TPO device you can perform investigations/comparisons of your canister oxygen results and perform some improvement tests on your lines if needed. Using the Haffmans formula you can have the HSO and DO values separately and you can also choose to compare the TPO results by making some measurements using the Uhlig formula.

Best Luck, 

------------------------------
Daniela El Alam

Here's the set-up with the cardboard box, foam inserts, and belt.  This does still require supervision because no matter how tightly I crank down the shaker, the box sometimes works itself loose.

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

Original Message:
Sent: 02-14-2024 17:39
From: Andrew Johnston
Subject: TPO calculation method

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.

------------------------------
Andrew Johnston
Production Brewery Manager
First State Brewing Co
Middletown DE
(302) 893-9005
------------------------------


Original Message:
Sent: 01-19-2024 04:51
From: Daniela El Alam
Subject: TPO calculation method

Hi Kelly, 

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

Try to use the following formula: 

Vvl= volume liquid

Vhs= volume head space

Do the comparison again and look at what are the results. 

With the Haffmans TPO device you can perform investigations/comparisons of your canister oxygen results and perform some improvement tests on your lines if needed. Using the Haffmans formula you can have the HSO and DO values separately and you can also choose to compare the TPO results by making some measurements using the Uhlig formula.

Best Luck, 

------------------------------
Daniela El Alam

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. 

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA
------------------------------

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.

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

Original Message:
Sent: 01-31-2024 13:42
From: Roger Barth
Subject: TPO calculation method

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. 

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA
------------------------------

Daniella's equation is equivalent to the Uhlig equation. The only difference is V(hs)/V(l) = HS/100. The is Uhlig gives the headspace ratio in percent.

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA
------------------------------

Original Message:
Sent: 01-31-2024 15:22
From: Kelly White
Subject: TPO calculation method

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.

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


Original Message:
Sent: 01-31-2024 13:42
From: Roger Barth
Subject: TPO calculation method

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. 

------------------------------
Roger Barth
Author (with M Farber) of Mastering Brewing Science ISBN 9781119456056
Retired
West Chester PA