Beer Lines and Fittings: Draught System Guide
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Beer lines and fittings form the sealed route between a keg, cooler and tap. Choosing the correct line diameter and compatible connectors helps maintain flow, temperature and beer quality while preventing leaks and unnecessary foam.
This guide explains the main components used in an Irish home draught system and how they work together. Browse TheKegCru's beer and gas line and beer-line fittings when planning or repairing a setup.
What Does a Beer Line Do?
Beer line carries the drink from the keg coupler through the cooler or kegerator to the tap. It must be food-grade, suitable for beverage use and correctly sized for the system. Its internal diameter, length, height change and resistance all affect how the beer pours.
A line that is unsuitable, damaged, kinked or incorrectly sized can contribute to slow flow, excessive foam or inconsistent pouring. Pressure should not be changed repeatedly to compensate for a basic line-layout problem.
Beer Line vs Gas Line
Beer line carries the product; gas line carries CO₂ or mixed gas from the regulator to the coupler. They perform different jobs and must be connected to the correct ports. Follow the markings on the coupler and regulator rather than relying only on tube colour.
Use line rated for its intended purpose and pressure. The vertical outlet on many couplers carries beer while the side port accepts gas, but always follow the instructions supplied with the exact keg coupler.
Common Beer-Line Sizes
TheKegCru supplies commonly used sizes including 3/8-inch beer line and 5/16-inch beer line. The correct size depends on the equipment and fitting specification. A measurement on the product may refer to the outside diameter rather than the internal bore, so match the complete specification instead of assuming that two tubes with similar labels will connect.
Do not reduce or enlarge a line simply to make an existing fitting work. Select compatible line and fittings together.
What Are Beer-Line Fittings?
Fittings connect line to couplers, taps, coolers, regulators and other system components. Common examples include:
- Push-fit straight connectors
- Reducers and adaptors
- Elbows for controlled changes in direction
- Shut-off valves
- Tailpieces, nuts, washers and clamps
- Non-return valves that help prevent reverse flow
Every fitting should be food-safe where it contacts beer and rated for the line and pressure involved. Browse draught beer fittings and connectors rather than using general plumbing parts.
Push-Fit Beer-Line Connectors
Push-fit connectors create a secure seal around correctly sized tubing. Cut the tube squarely with a suitable cutter, inspect it for scratches and push it fully into the fitting. A crooked or damaged cut can leak even if the line appears connected.
To remove the tube, isolate and depressurise the system first. Hold the fitting's collet inward while withdrawing the line. Never pull at a live pressurised connection.
How Fittings Affect the Pour
An unnecessary restriction, incorrect reducer, damaged washer or partly inserted tube can disturb flow. This can create turbulence, intermittent gas breakout or leaks. Keep the route simple, avoid sharp bends and use the fewest fittings needed for a safe installation.
Temperature is equally important. A correctly sized line will still foam if beer warms between the keg and tap. Check the beer cooler, line insulation and tap temperature before altering pressure.
Checking a New Draught-System Connection
- Confirm the keg's coupler type and required gas.
- Match the beer and gas lines to the stated fitting sizes.
- Cut flexible tube squarely and push it fully into each connector.
- Confirm washers, seals and non-return valves are present and correctly oriented.
- Secure the cylinder upright and open the gas slowly.
- Check gas connections for leaks using an approved leak-detection method.
- Inspect beer connections for moisture or product leakage during the first pour.
If you need help identifying a keg connection, use our keg coupler compatibility guide.
Cleaning and Replacing Beer Lines
Beer residue can support yeast, bacteria and biofilm, affecting flavour and flow. Clean beer-contact parts at the interval specified for the system and cleaning product, and between kegs where appropriate. Replace line that remains stained, scratched, hardened, tainted or difficult to clean.
Use approved products from our cleaning and maintenance collection. Never mix cleaning chemicals, exceed the stated concentration or reconnect beer until the system has been flushed and verified clear according to the chemical manufacturer's instructions.
Choosing Beer Lines and Fittings
Work from the equipment specifications: keg coupler, cooler, tap, regulator and the line ports on each component. If you are unsure, send TheKegCru photos or product names for the equipment plus the required line size. Matching the system before ordering prevents leaks, restrictions and incompatible connectors.