Hey Andrew,
For head pressure, you'd need to figure out a ratio that allows for partial pressure of the carbonation you are looking to maintain. That said, it is possible to effectively purge BTs with only N2. We installed our generator in April 2024 and previously brought N2 on as a process gas in April 2023.
Some of the lessons we learned:
- Purge from the top down - we connect through the sprayball and vent through the bottom port.
- For safety we vent all purge gas outside via a dedicated line. I second Liam's comments about O2 meter.
- 100% N2 purge takes ~20% longer than w/ CO2
- We build this into our schedule but the extra time is more than outweighed by the CO2 savings.
- We purge until tank O2% = <0.05%
- We flow through a rotameter and found ~150 Lpm at ~20psi to be ideal
- CO2 pressurize from the bottom up. We do pressurize with only CO2.
Generator info:
- Outlet gas purity: 99.995-99.999% (fluctuates due to demand and ambient temperature)
- Monitored in real time at the generator
- Max flow: 650 Lpm
- We run N2 at our can seamer and do not can and purge at the same time. Our schedule allows for this.
Generators are not novel but their adoption by the craft industry is and there are only a few good resources on MBAA and BA. Tim Lozen from Bell's organized a workshop at WBC last year on the topic - when it is available to watch in WBC Rewind I encourage you to check it out.
Our generator is on the short list for my favorite piece of equipment in the brewery and it has been a real game changer for us. Feel free to reach out if you want to chat more.
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Campbell Morrissy, PhD
Director of Brewery Operations
pFriem Family Brewers
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Original Message:
Sent: 12-16-2024 07:44
From: Liam Mckenna
Subject: Purging Tanks with CO2/N2 Blend
Purging with a blend is certainly possible however, you will want to consider the purity of nitrogen from your generator. N2 generators come in many grades from 95%-99.999% purity of gas yielded. I would think that the lower end generators would not be suitable for this purpose.
Also most importantly, you will need an O2 environmental sensor if you are purging and venting with nitrogen or a nitrogen blend. Most cellars have CO2 sensors for safety. Most do not have O2 sensors.
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Liam Mckenna
YellowBelly Brewery and Public House
St. John's
(709) 691-8584
Original Message:
Sent: 12-13-2024 12:10
From: Andrew Sanderson
Subject: Purging Tanks with CO2/N2 Blend
To All You Beer Gas Experts,
We recently had a bulk nitrogen generation system installed to lower our CO2 usage and for use with RTD beverages. We will be installing a blending box near our BBTs to use for head pressure and tank purging. My question is, does anyone have a specific blend of CO2/N2 they use for effectively purging oxygen out of there BBTs? For this process, we would like to use as little CO2 as possible but also be able to purge the BBT of oxygen in a reasonable amount of time. Thanks for any input.
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Andrew Sanderson
Quality Manager
Sly Fox Brewing Co
Pottstown PA
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