FOBs, Beer Pumps & Gas Blenders: What Your Long-Draw System Actually Needs
Three components, one job — getting beer from a remote cooler to the faucet without waste, foam, or over-carbonation. Here's when each one earns its place, how they work together, and how to decide between a beer pump and a gas blender.
The short answer
These three parts solve the problems that show up when beer has to travel a long way. A FOB detector stops foam and waste at keg changes. A beer pump moves beer when CO2 pressure alone can't. A gas blender mixes CO2 and nitrogen so you can push hard without over-carbonating.
If your kegs sit directly under the faucet (a kegerator or short under-bar run), you likely need none of them. Once you're running to a remote walk-in cooler, over ~25 feet of line, or pouring nitro beer, one or more becomes worth it. The order in a typical commercial system: Keg → FOB → Beer Pump → long beer line → Faucet.
How the three fit together
In a long-draw system, gas pressure, foam control, and flow are three separate problems. Each component owns one of them.
Which do I need?
Answer a few questions and we'll tell you which components your system actually needs — and which it doesn't.
A Foxx specialist will confirm it against your actual line length, cooler location, and beer list. Talk to an expert →
FOB detectors (foam-on-beer)
A FOB's one job: detect when a keg runs dry and shut off the line before foam and gas reach the faucet.
A FOB — short for "foam on beer" — sits between the keg coupler and the beer line, usually in the walk-in cooler. Inside is a float. When the keg is full, beer fills the chamber and the float rises, holding the valve open so beer flows freely. When the keg empties, the float drops and seals the outlet port, stopping foam and air from entering the long run. After you tap a fresh keg, you reset the FOB — venting the trapped gas — and pour clear beer immediately, with no waiting and no purging.
That matters most on long lines, because a long line holds a lot of product. Without a FOB, every keg change pushes the foam in the line out through the faucet as waste. A FOB keeps the line full of beer the whole time.
What a FOB prevents
Wasted beer at keg changes, excess foam, air entering the line, and inconsistent pours — plus the labor of bartenders purging lines and waiting for foam to clear.
Best for
- Long-draw systems — bars, stadiums, casinos, restaurants with kegs in a remote walk-in.
- Glycol-cooled systems, especially with multiple taps over long distances.
- High-volume setups, where minimizing beer loss per change adds up fast.
Usually not needed
- Simple direct-draw kegerators.
- Short-run home draft systems.
- Small 1–2 tap setups with the keg directly below the faucet.
The math on waste
A FOB typically saves about 2–4 pints of beer per keg change. A wall-mount foam control unit at Foxx saves roughly 4 pints per keg on a 125-foot run using 3/8-inch line. Across a moderate-volume bar, that adds up to 40–90 gallons saved per month — which is why a FOB tends to pay for itself quickly.
Maintenance
FOBs need cleaning on the same schedule as your beer lines. The Brewers Association suggests disassembling and detailing the FOB roughly every three months with beer-line cleaner. One firm rule: never bypass the FOB during line cleaning — cleaning fluid should run through it.
Beer pumps
Used when CO2 pressure alone can't move beer properly through the system.
On a short run, gas pressure in the keg does all the work of pushing beer to the faucet. Over a long distance, that breaks down: the pressure you'd need to push the beer would over-carbonate it. A beer pump separates the two jobs — the keg stays at the correct low pressure for carbonation, and the pump supplies the push. Foxx's pumps are gas- or air-driven and never touch the product, so the beer only contacts the line, not the pump mechanism.
When a pump is the answer
| Situation | Why a pump helps |
|---|---|
| Long-draw runs (often 50–500+ ft) | Pushes beer from cooler to faucet without the over-carbonation high CO2 pressure would cause. |
| Remote walk-in coolers | Maintains steady flow and pressure across the distance. |
| High-elevation / multi-floor | Overcomes gravity and line resistance on vertical runs. |
| Low-carbonation beers | Lets you keep keg pressure low — protecting carbonation — while still moving beer efficiently. |
Two types
Air- / gas-operated beer pumps use compressed gas or air to drive the pump and are the common choice for commercial long-draw systems. Electric recirculation / booster pumps are used in specialized or very large systems, often paired with glycol. Foxx carries gas-driven FloJet and SHURflo (Beer-Ace II) pumps that work on both short and long draw and serve up to four faucets.
Best for
- Commercial long-draw systems with significant line length.
- Remote coolers and vertical / multi-floor runs.
- Low-carbonation beers that can't tolerate high gas pressure.
Generally not needed
- Home kegerators.
- Direct-draw towers.
- Short draft lines under the bar.
Gas blenders
For when you need a precise mixed-gas pressure instead of straight CO2.
A gas blender (or gas mixing panel) blends CO2 and nitrogen on site to a set ratio. The reason it works: nitrogen is largely insoluble in beer. It adds pushing pressure without adding carbonation. So a blender lets you run higher pressure to move beer down a long line — or to hold stable pours across a system — without forcing extra CO2 into the beer and over-carbonating it. The typical path is gas cylinders → blender → regulators → beer lines.
Where blenders are used
| Application | What the blend does |
|---|---|
| Long-draw systems | Mixed gas allows higher push pressure to move beer long distances without over-carbonating. |
| Nitro beer systems | Stouts and similar beers use a nitrogen-heavy blend — commonly about 75% N₂ / 25% CO₂ — for their signature smooth pour. |
| Multi-zone systems | Different beers can require different pressures and gas blends across the system. |
| High-pressure remote systems | Pure CO₂ at high PSI causes foaming and over-carbonation; a blend reduces that risk. |
Foxx's McDantim TruMix dual blender is built for exactly the cases above — situations where over-carbonation is a problem, or where you're dispensing low-carbonation nitro beers — and includes a built-in adjustable secondary regulator. For shops that go through enough nitrogen, on-site nitrogen generators (producing ~99.8% pure N₂) can feed the blend instead of bottled nitrogen.
Best for
- Long-draw and high-pressure remote systems.
- Nitro beer (where the nitrogen blend is part of the pour itself).
- Multi-zone systems running different beers and pressures.
Usually unnecessary
- Small direct-draw systems.
- Home kegerators.
- Short-run draft systems using only CO₂.
Beer pump vs. gas blender: which one?
This is the decision most long-draw buyers actually wrestle with — because both solve the same problem from opposite ends.
The shared problem: you need to move beer a long way, and straight CO2 at the pressure required would over-carbonate it. A blender fixes it by changing the gas — add nitrogen and you can push harder without adding carbonation. A pump fixes it by changing the mechanism — keep the keg at the right low CO2 pressure for carbonation and let the pump do the pushing. In fact, some Foxx beer pumps are designed to eliminate the need for a gas blender and nitrogen generator altogether.
| Beer pump | Gas blender | |
|---|---|---|
| How it solves long-draw | Mechanical push; keg stays at correct carbonation pressure | Adds nitrogen so higher push pressure doesn't over-carbonate |
| Carbonation control | Precise — keg pressure set purely for the beer | Managed via blend ratio and pressure |
| Added supply needed | A gas/air drive (or electric); no nitrogen required | Nitrogen — bottled or from a generator |
| Moving parts | Yes — a pump to maintain | No mechanical pump on the liquid side |
| Nitro beer | Doesn't substitute — nitro still needs a blend | Required |
Short version: if you're pouring nitro, you need a blender no matter what. If your goal is the most precise carbonation with the lowest ongoing gas cost, a pump is often the cleaner answer. Many systems use a combination. The right call depends on your beer list, line length, and how much nitrogen you'd otherwise buy — which is worth a quick conversation before you spec it.
Spec it with a Foxx expert
Send us your line length, cooler location, faucet count, and beer list. We'll tell you exactly which of these you need — and which you don't — instead of selling you the whole stack.
Frequently asked questions
Do I need a FOB detector?
How much beer does a FOB detector save?
Do I need a beer pump?
What's the difference between a beer pump and a gas blender?
What gas blend is used for nitro beer?
In what order do these components go in a draft system?
Foxx Equipment Company — commercial beverage dispensing equipment and expertise. Component need depends on your specific system; figures above are typical ranges, not guarantees. Contact a specialist to spec your draft system.