What happens when you change a keg
Changing a keg means disconnecting an empty barrel from your tap system and connecting a full one in its place. The process takes about five to ten minutes once you know the steps. You will need to release pressure from the empty keg, disconnect the gas and beer lines, remove the keg, install the new one, reconnect both lines, and restore pressure to the system.
The exact procedure depends on whether your keg system uses a ball lock connector (common in home setups) or a pin lock connector (common in commercial bars). Both work the same way in principle but have different release mechanisms. This guide covers ball lock systems, which are more common in residential and small-business settings.
Key Takeaways
- Turn off the CO2 tank or regulator before you disconnect anything, so pressure does not spray beer or gas into your face.
- Release the pressure valve on top of the keg to equalize pressure inside and outside before pulling the connectors.
- The gas line (usually black) and beer line (usually clear or white) pull straight out once you press or twist the release collar, depending on your connector type.
- Set the new keg in place, reconnect both lines firmly until you hear or feel a click, then turn the CO2 back on and check for leaks at the connections.
- If beer sprays when you disconnect, you did not release enough pressure — turn off CO2 and wait a few seconds before trying again.
Turn off the gas supply before you start
Locate the CO2 tank or the regulator valve on your tap system. Turn the valve clockwise until it stops — do not force it. This stops new gas from entering the keg and prevents pressure from building while you work.
If you have a separate CO2 tank (common in home keg systems), turn the valve on the tank itself. If your system is built into a bar or cooler, look for a knob or lever on the regulator mounted to the side or back. Turning off the gas first is the most important safety step because it prevents pressurized beer or gas from spraying when you disconnect the lines.
Release pressure from the empty keg
Look at the top of the keg. You will see a small metal valve sticking up — this is the pressure relief valve. Press down on it with your finger or a small tool to release the gas inside. You will hear a hiss as pressure escapes. Hold it down for two to three seconds, then release.
This step equalizes the pressure inside the keg with the air around it, so the connectors will pull off without resistance or spray. If you skip this step, beer or foam will spray out when you disconnect the lines. If you are changing a keg that has been sitting for a while, the pressure may be lower already, but releasing it anyway takes only a few seconds and prevents surprises.
Disconnect the gas and beer lines
You will see two connectors attached to the top of the keg — one for gas (usually black) and one for beer (usually clear, white, or red). Both use the same release mechanism. For a ball lock connector, squeeze or press the collar around the base of the connector while pulling straight out. The connector should come free with a soft click or pop.
If the connector does not move, you may not have released enough pressure. Turn off the CO2 again, press the relief valve on top of the keg for another few seconds, and try again. Once both lines are disconnected, set them aside on a clean surface. Do not let the beer line drip onto the floor — have a towel or bucket ready if the line is still wet.
Remove the empty keg and position the full one
An empty keg weighs about 30 pounds and is awkward to handle. If the keg is in a cooler or stand, tilt it slightly and roll it out on its bottom edge. If it is sitting on a flat surface, grip it by the handle or the sides and lift straight up. Set it aside in a safe place where it will not roll.
Position the full keg in the same spot, making sure it is stable and level. If it is in a cooler, roll it into place and make sure the top is accessible. The keg should sit firmly on the ground or on whatever surface it was on before — it should not rock or shift when you push on it gently.
Reconnect the gas and beer lines
Take the gas line (usually black) and push it straight onto the gas connector on top of the new keg. Push firmly until you hear or feel a click — this means the ball lock has seated and the connection is secure. Do the same with the beer line, pushing straight on until it clicks.
Both connectors should be tight enough that you cannot pull them off by hand without pressing the release collar. If either line feels loose or wiggles, disconnect it and reconnect it again. A loose connection will leak gas or beer and waste product.
Turn the gas back on and check for leaks
Turn the CO2 valve counterclockwise to restore gas to the system. Turn it slowly — you do not need to force it. Once the valve is open, listen and watch the connections you just made for any hissing sound or visible bubbles in the beer line.
If you see bubbles or hear hissing, turn the gas off immediately, disconnect the leaking line, and reconnect it. Most leaks happen because the connector did not seat fully. If the leak continues after reconnecting, the connector itself may be damaged — in that case, you may need to replace the line or connector before you can use the keg. Once everything is tight and dry, the keg is ready to pour.
Frequently Asked Questions
What if beer sprays out when I disconnect the lines?
You did not release enough pressure from the keg. Turn off the CO2, wait 10 seconds, then press the relief valve on top of the keg for three to five seconds. Try disconnecting again. If it still sprays, release pressure one more time and wait longer before disconnecting.
How do I know which line is the gas line and which is the beer line?
The gas line is almost always black. The beer line is usually clear, white, or red. If you are unsure, the gas line connects to the smaller post on top of the keg, and the beer line connects to the larger post. The connectors are sized differently so you cannot plug them into the wrong post.
Can I change a keg without turning off the CO2?
You can, but you risk getting sprayed with beer or foam. Turning off the gas takes five seconds and prevents mess and waste. It is worth doing every time.
What if the connector is stuck and will not come off?
Make sure you released the pressure valve on top of the keg. If pressure is still in the keg, the connector will not budge. Release pressure again, wait a few seconds, then try pulling the connector straight out while pressing the release collar. Do not twist or wiggle it — pull straight.
How tight should the connectors be on the new keg?
Push them on until you hear or feel a click, then stop. They should be snug enough that you cannot pull them off by hand without pressing the release collar. If you have to force them or use a tool, something is wrong — disconnect and try again.