Kegerator Keg Probes: Types and Compatibility

What a keg probe is

A keg probe is the tube that extends from a keg coupler into the keg. On a listing, the coupler is described as the part that attaches to the keg opening, and the probe is the part of that coupler that goes inside the keg. The probe is what connects the dispense line to the contents of the keg.

Do not confuse a keg probe with a temperature probe. A temperature probe is the sensor that reads the cabinet air temperature for the thermostat; a keg probe is a dispense component. When a listing says "probe" without the word "keg", it usually refers to the temperature sensor. The two parts are separate, and a kegerator includes both. See where the temperature probe is placed for that sensor.

Probes appear on coupler listings, on keg listings, and inside the bullet list of a kegerator that includes a coupler. The connector type is usually stated; the length is stated less often.

Ball lock probes

Ball lock is one of the two common connector standards for keg couplers. A ball lock probe uses a ball-and-groove connection: the probe slides into the keg fitting and a ball bearing locks it into place. The name "ball lock" comes from that locking mechanism.

A ball lock probe fits a ball lock keg. Ball lock kegs are the more common type on the homebrew-style market, so a coupler with a ball lock probe is what most consumer kegerator listings include. If a listing does not name a connector type, the default is usually ball lock.

When the listing says "ball lock coupler", the probe is the tube on that coupler. Read the bullet list for the phrase "ball lock" to confirm the type before you compare models. See how ball lock compares to pin lock for the full comparison.

Pin lock probes

Pin lock is the other common standard. A pin lock probe uses a pin-and-slot connection instead of a ball bearing. The probe slides in and pins hold it in place. A pin lock keg is designed for that connector, and a ball lock probe will not fit it.

A pin lock probe fits a pin lock keg only. The two standards are not interchangeable: a ball lock probe will not fit a pin lock keg, and a pin lock probe will not fit a ball lock keg. If you already own pin lock kegs, you need a coupler with a pin lock probe.

Some listings sell an adapter so a ball lock coupler can connect to a pin lock keg. An adapter is a separate part and is not the same thing as a matched probe. Read the listing for the word "adapter" if you plan to connect the two keg standards.

Probe length and what it tells you

Probe length is the distance from the coupler to the end of the tube that reaches into the keg. A probe has to be long enough for the keg it is meant for and short enough to clear the bottom of the keg. A listing may state the length or leave it out.

When a listing does not state the length, the stated keg size is the best guide. A coupler sold with a small keg has a probe matched to that keg; a coupler sold with a full-size keg has a probe matched to the taller keg. Match the probe to the keg size you plan to use.

For most buyers the practical rule is simple: buy the coupler and probe that the listing pairs with the keg size you want. If the listing states a probe length, read it; if it does not, read the stated keg size instead. See reading keg size compatibility for how the two work together.

Which kegs the probes fit

Ball lock and pin lock probes are both made for homebrew-style kegs, the kegs that originally held soda and are now used for draft setups. They do not fit commercial full-size kegs, which use a different coupler standard, often called the D-system or S-system.

The stated keg size on a kegerator listing tells you which coupler family the unit uses. A listing that shows a small homebrew-style keg with a single connector uses a ball lock or pin lock probe. A listing that shows a full-size commercial keg uses the commercial coupler, not a ball or pin lock probe.

If the listing does not state a probe type, use the stated keg size as the clue. Homebrew-style kegs take ball lock or pin lock probes; full-size commercial kegs take a commercial coupler. The D-system versus S-system comparison explains the commercial side.

Reading probes in kegerator listings

On a kegerator listing, the probe type appears in the description of the dispense setup. Look for the phrase "ball lock coupler" or "pin lock coupler"; the probe is part of that coupler and is rarely named as a separate line.

When the listing says "coupler included", the probe comes with the coupler. When it says "coupler sold separately", the probe comes with the coupler you buy separately, not with the kegerator. Read that line before you compare units.

A listing that does not state the probe type is not automatically a problem. The stated keg size, the tap count, and the brand can tell you what kind of keg the unit is meant for. Compare units on those stated details: kegerator comparisons are built on the details the seller states.

What a listing leaves out

A listing cannot tell you whether a probe will work with a keg you already own unless it states the connector type. "Ball lock" and "pin lock" are the only words that settle that question. If neither appears, the connector type is not stated by the seller.

Some listings do not state whether a coupler and probe are included. The phrase "coupler not included" means the probe is a separate purchase. The phrase "coupler included" means the probe is part of the unit.

If the listing says the unit holds a specific keg size, read that as a statement about the coupler and probe setup. The probe is sized for that keg, and you match your keg to it. For the full picture, read how couplers are listed.

What to pick for your situation

Questions

What is a keg probe?

A keg probe is the tube that extends from a keg coupler into the keg. It carries the contents from the keg to the dispense line. It is separate from the temperature probe that reads cabinet air.

What is the difference between a ball lock and a pin lock probe?

Ball lock and pin lock are two connector standards. Ball lock uses a ball-bearing lock, and pin lock uses pins. A probe of one type does not fit a keg of the other type.

Do ball lock and pin lock probes fit the same kegs?

No. A ball lock probe fits a ball lock keg, and a pin lock probe fits a pin lock keg. The two keg standards use different fittings.

What probe length do I need?

Match the probe to the keg size the listing states. A coupler sold with a keg size has a probe for that keg. If the listing states a length, read it; if not, use the stated keg size as the guide.

Is a probe the same as a coupler?

The probe is a part of the coupler. A coupler listing includes the probe; a kegerator listing that says "coupler included" includes the probe as well.

Can I connect a ball lock probe to a pin lock keg?

Not directly. An adapter can connect the two standards, but the adapter is a separate part sold apart from the probe. Use a matched probe when you can.