# Beer Gas Mixes Explained: CO2, N2 & 75/25 | Portland Pros

> Pure CO2 vs nitrogen vs 75/25 beer gas blends, which pour needs which gas, effects on foam and carbonation, and regulator basics.

URL: https://commercialrefrigerationrepairportland.com/guide/beer-gas-mixes-explained/
Last-Modified: 2026-08-06

Guide

# Beer Gas Mixes Explained

Pure CO2, nitrogen, and 75/25 blends: which pour needs which gas, how blend choice changes foam and carbonation, and how regulators fit in.

Published August 6, 2026 · 5 min read

![Beer gas cylinders and regulators in a Portland taproom cellar feeding draft lines](/images/featured/row-of-beer-gas-cylinders-and-regulators-lined-up-.webp)

## Three Gases, Three Jobs

Beer gas is not one product. Understanding why comes down to a single physical property: how readily each gas dissolves into beer.

**Pure CO2** dissolves readily. That is what carbonates beer in the first place, and it is why CO2 is the standard push gas for most draft systems. On a short line from a cold keg to a nearby faucet, pure CO2 at the right pressure holds the beer at its intended carbonation and moves it to the tap. Simple and correct.

**Nitrogen** barely dissolves at all. It pushes without carbonating. That makes it useless on its own for a standard pour, which needs to keep its carbonation, but essential for nitro pours where the tight creamy head and cascading effect come precisely from nitrogen’s refusal to dissolve.

**Blends,** most commonly 75/25 nitrogen to CO2, split the difference. Enough CO2 to maintain carbonation, enough nitrogen to deliver push pressure without over-carbonating.

Our 

commercial gas delivery

[/commercial-gas-delivery/ →](/commercial-gas-delivery/)

 accounts supply all three across the Portland Metro area, and the right choice depends almost entirely on your draft system layout.

![Nitro pour and standard CO2 pour side by side showing the difference in head](/images/content/nitro-pour-and-standard-co2-pour-side-by-side-in-g.webp)

## Matching Gas to System

| System | Right gas | Why |
| --- | --- | --- |
| Short draw, keg near tap | Pure CO2 | Low pressure needed, carbonation maintained |
| Long draw to a distant walk-in | 75/25 blend | High push pressure without over-carbonating |
| Elevated taps above the cooler | Blend | Pressure must overcome elevation |
| Nitro stout or nitro coffee | Nitrogen or nitro blend | Cascade and dense head require nitrogen |
| Fountain soda | Pure CO2 | Carbonation is the entire point |
| Cask or hand pull | None, or minimal | Traditional dispense uses no gas push |

The dividing line is line length and pressure. A short-draw system needs only enough pressure to maintain carbonation and move beer a few feet. A long-draw system running to a remote walk-in needs substantially more pressure to overcome line resistance, and at that pressure pure CO2 will over-carbonate the beer sitting in the line.

## What Wrong Gas Looks Like in the Glass

**Foaming on every pour** with pure CO2 on a long line usually means over-carbonation from excess pressure. The gas keeps dissolving into stationary beer in the line between pours.

**Flat pours** mean too little pressure, or a blend with too little CO2 for the style.

**A nitro faucet producing ordinary foam** means CO2 where nitrogen should be.

**Inconsistent pours across taps** on a shared regulator usually means one line needs different pressure than the others, which is a manifold and secondary regulator question rather than a gas question.

![Primary and secondary beer gas regulators on a manifold feeding multiple keg lines](/images/content/primary-and-secondary-beer-gas-regulators-mounted-.webp)

> **Check the easy things first**
> 
> Before changing gas, confirm your beer lines are properly chilled along their entire run, that they have been cleaned on schedule, and that faucet type matches the pour. Warm or dirty lines produce foam no gas blend can fix, and they are far more common than a gas selection error.

## Regulators, Manifolds, and Pressure

A primary regulator sets system pressure off the cylinder. Secondary regulators let you tune individual product lines, which matters when you are pouring styles that want different pressures off one gas source.

A manifold lets multiple cylinders feed one system, so swapping an empty does not interrupt service. For any bar running significant volume, a manifold plus a backup cylinder is the single most effective anti-outage setup available.

Set pressure deliberately for your system, then leave it alone. Regulators adjusted nightly by whoever is closing produce inconsistent pours and burn gas.

## Getting the Blend Right for Your Bar

Tell us your line lengths, elevation from keg to tap, what styles you pour, and whether you run nitro. That is enough to specify the blend and pressure your system should be on.

For non-beverage applications, our guide on 

nitrogen, argon, and specialty gas

[/guide/nitrogen-argon-specialty-gas-commercial/ →](/guide/nitrogen-argon-specialty-gas-commercial/)

 covers purity grades and industrial uses.

## Blend Ratios and What Sits Behind Them

The 75/25 label refers to the nitrogen-to-CO2 ratio by volume, and it is a convention rather than a law. Other ratios exist and are used deliberately.

A higher CO2 fraction suits shorter lines and styles that want more carbonation held in the glass. A higher nitrogen fraction suits very long runs, high elevation between cooler and tap, and styles where a softer carbonation reads better. Nitro-specific pours sit at the extreme end, effectively all nitrogen.

The ratio you need is a function of your system rather than your taste. Line length, internal diameter, vertical rise from keg to faucet, and cooler temperature together determine the pressure required to deliver beer at the right speed. Once you know that required pressure, the blend is chosen so the CO2 partial pressure within it matches the carbonation the beer should hold. Push harder than that with pure CO2 and you carbonate the beer further in the line; push softer and it goes flat.

Most Portland bars we set up land on either pure CO2 for a short-draw system or a standard nitrogen-heavy blend for long-draw. The unusual ratios are worth discussing only when something about your system is genuinely unusual.

## Storage, Handling, and Swapping

Blend cylinders store the same way as CO2: upright, secured against tipping, ventilated, away from heat, and out of walkways. Keep full and empty clearly separated so nobody connects an empty during service.

Label which regulator feeds which product line. In a cellar running pure CO2 for soda and a blend for draft, mixing the two up is easy to do at speed and produces a confusing pour problem that takes a while to trace back to the gas.

Tell us your line lengths, rise, and style mix and we will specify the blend and pressure your system should run.

Related service

## Learn more about Gas Delivery

Pre-scheduled and emergency commercial gas delivery throughout the Portland Metro Area.

Gas Delivery

[/commercial-gas-delivery/ →](/commercial-gas-delivery/)

 

(971) 757-3066

[tel:+19717573066 →](tel:+19717573066)

FAQ

## Questions We Get About This

When do I need a 75/25 blend?

When your draft lines are long, when they run to a distant walk-in, or when you are pushing at higher pressure to overcome elevation and line resistance. Pure CO2 at that pressure keeps dissolving into the beer on the way to the tap, so you end up over-carbonated and foamy. A nitrogen-heavy blend gives you push without extra carbonation.

Can I use CO2 for nitro pours?

No. Nitro pours need nitrogen or a nitrogen-dominant blend. The signature cascade and dense creamy head come from nitrogen's low solubility in beer, which is exactly what CO2 does not do. Pure CO2 through a nitro faucet produces a foamy mess rather than a nitro pour.

Will switching gas fix my foaming problem?

Sometimes, but check the other causes first. Warm beer lines, dirty lines, incorrect faucet type, wrong pressure setting, and restrictive line runs all cause foam. Gas blend is one variable among several, and switching gas on a system with warm lines will not help.

Is nitrogen more expensive than CO2?

Per cylinder, blends generally cost more than pure CO2, but the relevant comparison is total cost including wasted product. A system that foams half a pour is throwing away beer continuously. On long-draw systems the blend usually pays for itself in reduced waste.

## Related Guides

### CO2 Delivery for Bars, Restaurants & Soda Systems

Where CO2 gets used behind the bar, why food-grade matters, how cylinder sizes and refill cadence work, and how to store cylinders safely.

[CO2 Delivery for Bars, Restaurants & Soda Systems →](/guide/co2-delivery-for-bars-restaurants/)

### How Commercial Gas Delivery Scheduling & Pricing Works

Scheduled versus on-demand delivery, how gas pricing is structured, what an account involves, and where our Portland-area coverage reaches.

[How Commercial Gas Delivery Scheduling & Pricing Works →](/guide/commercial-gas-delivery-scheduling-pricing/)

### Cylinder vs. Bulk Gas Delivery: Which Is Right for Your Business

Where the crossover point sits between high-pressure cylinders and bulk gas: usage thresholds, storage and siting, cost per unit, and delivery logistics.

[Cylinder vs. Bulk Gas Delivery: Which Is Right for Your Business →](/guide/cylinder-vs-bulk-gas-delivery/)

### Emergency Gas Delivery: What to Do When You Run Out

Out of CO2 or beer gas mid-shift? Immediate steps, what emergency delivery involves, and the safety-stock setup that stops it happening again.

[Emergency Gas Delivery: What to Do When You Run Out →](/guide/emergency-gas-delivery-run-out/)