Ask The Brewmasters

I recently had a situation with my CO2 lines leaving my bulk tank headed to the splitter. The line became discolored an oily looking brownish color and began to bulge near fittings. it appeared to start at the exit of the bulk tank and faded as it progressed down the line, with some apparent settling in low spots. I did some basic sensory testing by bubbling co2 through water and tasting/ smelling with no apparent off-ness. Gas company says that it's due to the acidity of CO2 breaking down the hose polymers. I was wondering if anyone had run into similar issues, and what can be done to prevent this in the future. Different hose material? Thanks for any insight.

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Ryan Drew
Head Brewer
Gild Brewing
Missoula MT
(406) 281-0916
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This message was posted by a user wishing to remain anonymous

Hi Ryan, 

I have only ever seen this in a Rapeseed Oil plant when Warm pressed Oil is being filled into IBC's for Packaging. The Oil at 45 to 50 degrees was very destructive to a conventional filling hose and was not material compliant. I found Superflex Polyurethane Ducting (Eolo Food grade) to be the solution for this. The Hose doesn't degrade under harsh conditions. 

Ryan,

Check out the MBAA podcast #186 CO2 systems and quality. I don't know the timestamp, but they discuss discoloration in CO2 lines like this. 

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Weston Barkley
Head Outpost Brewer
BrewDog Las Vegas
Las Vegas NV
(702) 372-6461
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Hey Ryan,

Gabriel Dominguez of Pentair taught me much about the properties of CO2 - things I wish were taught in brewing school! 

For example, a couple of things - 

First, liquid CO2 is delivered to most breweries via tanker truck. It is transferred to onsite liquid storage with hoses. Well, CO2 is a solvent. Over time, it can dissolve the hose liner and delivered an oily material to the bulk tank that settles to the bottom. It builds up over time. If you pull from a bottom outlet, you'll deliver this oily substance to your process. Gabriel recommends that liquid CO2 be delivered via a hose rated for liquid CO2 transfer. I suspect some CO2 suppliers are not using such hoses?

Secondly, unrelated to your question but so important that I'll mention it. Sometimes brewers "blow down" their CO2 bulk tank to purge oxygen. Most CO2 bulk tanks are rated for a Minimum Allowable Operating Temperature of -40 deg. Gabriel warned me to never allow this tank pressure to drop below 190 psi as the liquid gets dangerously close to -40 deg which will compromise the integrity of the steel wall. Then, when you repressurize to a typical operating pressure (circa 250 psi), the tank can rupture violently. This has happened leading to horrific consequences. So, it's a real concern. This scared me so much that we installed redundant alarms and interlocks to prevent the tank from going below 220 psi with a second fail safe at 205 psi.

Regards,

Daniel Carey

New Glarus Brewing

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Daniel Carey
Brewmaster
New Glarus Brewing Company
New Glarus WI
(608) 527-5850
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