Ask The Brewmasters

Wow, N2 generators are so hot right now! Just an FYI there is a similar thread about purging BTs with generated N2.

We spent a lot of time looking at this balance when choosing, installing, and tuning in our generator. We were back and forth deciding between a Holtec and Parker unit and one of the reasons we went with Holtec was that it was rated for the the same purity at a lower inlet air pressure (flowrates were the same). This allowed us to install without upgrading our compressed air plant. 

Despite what some vendors will claim, we found that for many processes, we did need to generate high purity N2 (99.99 - 99.999%) to mimic the performance of CO2*. You also may find that your unique process and equipment requires a purity that doesn't match another brewery's requirements. The nice thing is that most generators will allow you to modulate the operating conditions** in order to achieve your target purity. Our is monitored via an O2 sensor with thresholds that we can plug into to set alarm conditions. Our goal is N2 removal so there is probably trace CO2 and Argon in the N2 stream that we wrap into that purity %. 

The area we look at most and the main driver behind the install is N2 at the can seamer. We run N2 exclusively on the bubble breaker and under lid gassing star. Speaking to another well respected brewery, we were told that we should have 99.995% or better to keep TPO in spec. We've confirmed those findings and further found anything lower than 99.99% produces a >10 ppb penalty. Depending on your internal specifications for TPO that may be acceptable if you can reduce your operating costs on the generator. For us, we run a pretty low TPO spec and want to maintain/improve any place we can. If you have the ability to modulate flow, and thus N2 purity, you can dial it in to provide the balance that works for your brewery. We also use that purity for BT purges and adjunct additions into FVs or BTs - but that is based on convenience as the can seamer is the main user in the brewery and not measurements in those areas. 

I'd be happy to speak to our experience if you have other questions. 

*we didn't regularly measure our purchased CO2 purity to audit the suppliers claims. Just FYI. 

**a major driver is the ambient temperature of the room the generator is in. While we knew that this would have an impact we were surprised by how noticeable it was We saw a 0.005-0.01% purity penalty when running in a non-climate controlled room during the summer (+50-100ppm O2). We've since ducted the air compressors outside, dropping the temp of the room by 25°F in the summer and immediately saw an improvement in performance. Bonus, we can duct the air back into the room in the winter to keep it at a nice temp. I know other folks will have HVAC dedicated for this purpose. 

Hi Campbell, 

What method was used to measure the purity of the Gas? Our N2 generator engineer said the Anton Paar Carbo QC did not measure DO in gas form, but yet high purity N2 is used in gas form to blank check the DO measurement. Based on this I couldn't understand how our result of N2 gas from the generator was not deemed valid by the Supplier. 

Wow, N2 generators are so hot right now! Just an FYI there is a similar thread about purging BTs with generated N2.

We spent a lot of time looking at this balance when choosing, installing, and tuning in our generator. We were back and forth deciding between a Holtec and Parker unit and one of the reasons we went with Holtec was that it was rated for the the same purity at a lower inlet air pressure (flowrates were the same). This allowed us to install without upgrading our compressed air plant. 

Despite what some vendors will claim, we found that for many processes, we did need to generate high purity N2 (99.99 - 99.999%) to mimic the performance of CO2*. You also may find that your unique process and equipment requires a purity that doesn't match another brewery's requirements. The nice thing is that most generators will allow you to modulate the operating conditions** in order to achieve your target purity. Our is monitored via an O2 sensor with thresholds that we can plug into to set alarm conditions. Our goal is N2 removal so there is probably trace CO2 and Argon in the N2 stream that we wrap into that purity %. 

The area we look at most and the main driver behind the install is N2 at the can seamer. We run N2 exclusively on the bubble breaker and under lid gassing star. Speaking to another well respected brewery, we were told that we should have 99.995% or better to keep TPO in spec. We've confirmed those findings and further found anything lower than 99.99% produces a >10 ppb penalty. Depending on your internal specifications for TPO that may be acceptable if you can reduce your operating costs on the generator. For us, we run a pretty low TPO spec and want to maintain/improve any place we can. If you have the ability to modulate flow, and thus N2 purity, you can dial it in to provide the balance that works for your brewery. We also use that purity for BT purges and adjunct additions into FVs or BTs - but that is based on convenience as the can seamer is the main user in the brewery and not measurements in those areas. 

I'd be happy to speak to our experience if you have other questions. 

*we didn't regularly measure our purchased CO2 purity to audit the suppliers claims. Just FYI. 

**a major driver is the ambient temperature of the room the generator is in. While we knew that this would have an impact we were surprised by how noticeable it was We saw a 0.005-0.01% purity penalty when running in a non-climate controlled room during the summer (+50-100ppm O2). We've since ducted the air compressors outside, dropping the temp of the room by 25°F in the summer and immediately saw an improvement in performance. Bonus, we can duct the air back into the room in the winter to keep it at a nice temp. I know other folks will have HVAC dedicated for this purpose.