Ask The Brewmasters

My current SOP at the end of a brew and completing knockout is to run a good hot rinse forward and backward through the HX to remove gross particulates, then to run a hot caustic forward and backward. After this, I will push the caustic out very well forward and then backward with hot water, after which I slowly reduce the internal temperature to ~90°F prior to finally charging the HX, and upstream piping with PAA. All chemicals, including caustic are kept within the supplier's recommended range for use rates, and my water is moderate in total hardness & mineral content (~380 microsiemens in conductivity, for reference).

I am wondering if you've got any advice for whether this is a good practice to leave the HX charged with PAA before the next batch. For reference, this PAA also has a small amount of nitric acid as a part of the blend. It is not uncommon for a week to pass between brews, and I have recently begun to wonder whether I might be damaging gaskets by leaving the PAA in contact with the HX for this extended period.

Thank you for your assistance.

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Travis Kocurek
Hound Song Brewing Co
Columbus TX
(979) 942-7199
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Travis,

One of the reasons we use PAA is because it breaks down so quickly. After a day, or so, you’ll just have a HX packed with water. After our cleaning cycle, we leave our packed with caustic. Before the next brew, we blow it out with hot water. This has worked very well for us over the last 10 years. Hope to see you at the San Antonio meeting this weekend!

Blake
Lone Pint Brewery

Hi Travis,

I would suggest not leaving your HX packed with PAA for extended periods (for the very reason you question). We Run a very similar SOP but then rinse and pack the HX with cool water. We re-sanitize the HX and line on Brewday.

Cheers
Kirk

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Kirk Lombardi
Brewer / Manager
Zwei Brewing Co.
Fort Collins,CO.
kirk@zweibrewing.com
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Dear Travis:

My advise is to never leave any piece of equipment packed with chemicals. Depending on the quality of your water, any residuals in the HX and the stabilization of your Peracetic Acid, your sanitizer may be active anywhere from a day or two up to a week.  Both PAA and Nitric Acid are oxidative and will over time given long-term exposure cause damage to your gaskets and any other elastomers in the system.  The other problem you have is the expansion and contraction of liquids during day and night and sometimes changing temperatures.  This will cause the liquid to contract during the night, creating air pockets where residual PAA can cause pitting. This is especially true when using halogen sanitizers like iodophor or similar.  We worked on a pilot program in the 90's with Pabst where PAA was applied to the exterior of the filler.  A dramatically increased wear and tear was observed which could be traced back to the application of the PAA.  The same will happen here. 

Sanitize the HX, then rinse and pack with water.  Sanitize your HX again prior to use and you will see a dramatically increased lifespan on your gaskets. This is especially true when the HX sits for a week or longer since the PAA will break down and the acetate (breakdown product) may actually contribute to organic growth.

I hope this helps and contact me directly or here for more information. 

Cheers,

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Dirk Loeffler
CEO/Technical Director
Loeffler Hygiene & Safety Solutions
(404) 229-7583
loeffler.dirk@loefflerhygiene.com
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