Draft Beer Connections (fittings) Explained; MFL, FFL, MPT, FPT, Barb, BSPP and How They're Used

Sometimes the connections used when putting together a draft beer system can be a little confusing. I have been building systems for over 20 years and I still get confused! This article will break down what connections are used where and decipher a lot of acronyms. I will also poke a little fun at how our industry actually calls some connections one thing when they are actually another. Well, I know you can’t wait to get started on this incredibly interesting subject (yes, that was sarcasm), so let’s get going.

Conversion Table: CMB Nipple (barbed) Sizes

Additional Notes: Most people use larger size barbs on softer vinyl hose. For example if you are using a 5/16 ID hose most installers would use the 6mm, not the 4mm. The 7mm works best for 5/16.

Barb Fittings in Draft Beer Systems

Barbs - This is my favorite because it is so straight forward…except in the draft beer industry.

• 1/4" Barb: This is one of the most used barb sizes in draft beer systems. It is most often used for beer lines, both 3/16” and ¼” inside diameter (I.D.). When connecting to a standard 3/16” beer line it is actually so tight that you will normally need to heat up the end of the hose slightly in hot water. What I do is just heat some water in a coffee cup and dig the end of the hose in for about 20 or 30 seconds. Then the hose will easily go over the barb and you can use a 13.3 Oetiker clamp or worm clamp.
• 3/16" Barb: You would think this would be used for 3-16” ID lines, but it rarely is. Frankly, you would be hard pressed to see anyone using a 3/16” barb.
• 5/16" and 3/8" Barb: This is the size that will drive you crazy in the draft beer industry. They are most often used for standard gas lines, which are normally 5/16” inside diameter. The problem is that most manufacturers and installers in our business are often using a ?” barb, not a 5/16. We use a ? for gas line on most beer couplers, but some manufactures supply an actual 5/16 barb. I could go on and on with examples, but in the end the important thing to remember is that IT DOES NOT MATTER! You standard gas hose does not care if you use a 5/16” barb or ?” barb, they both fit and seal just fine.
• 4mm, 6mm, 7mm, 10mm Barbs: These are the most common sizes of metric barbs used in our industry, but they are not used to a large degree in the USA market. Here is a chart showing you how to convert these sizes to more standard sizes used in the USA.

NPT (National Pipe Thread) Fittings

NPT (National Pipe Thread) - These are pipe thread connections that are widely used in the USA. There are two types, MPT (male pipe thread) and FPT (female pipe thread). This thread, unlike its British counterpart, is tapered. This means that as you tighten the MPT into the FPT it gets larger the more you tighten. This helps the thread seal, but it is important to note that you still need to use a pipe sealant like teflon tape or a paste when connecting to eliminate leaks. Also note that if you tighten the thread too much it is actually possible to crack some components due to the pressure and the threads taper up.

• ¼” NPT: is by far the most commonly used size in draft beer equipment. This is the connection found on beer regulators, air distributors/manifolds and other draft equipment.

BSP (British Standard Pipe) Fittings

BSP (British Standard Pipe) comes in two configurations, one is tapered like it’s American counterpart, but the most widely used by far is the straight thread version.

• BSPP (British Standard Pipe Parallel): is a straight thread and it is very popular all over the world. It is not used much in the USA and was almost never used in the draft beer industry until we saw more Chinese imports on the homebrew side. It normally seals with an o-ring or gasket. Again, you do see this but it is very rare in Draft Beer.
• BSPT (British Standard Pipe Tapered): is a type of thread I have never seen used in the USA on draft equipment. Normally if it is tapered in our industry it is NPT.

MFL and FFL Fittings

MFL and FFL -This is a very common thread used with draft beer. It is most commonly used in ¼” size, but can also be found in ?” and ½” in some applications. However, do note that the ¼” MFL/FFL is not actually ¼”, it is a 7/16”-20 UNF thread. Why is it called ¼” by everyone in our industry…..I have no idea.

This thread works fantastic in areas where you want to take the thread on and off from time to time or even frequently. Some examples of its use would be with a beer regulator where the hose attaches, on air distributors where the outgoing hose is attached, on disconnects for homebrew style kegs and on many other parts. If you are going metal to metal you need a flared washer, but with CMB brand disconnects this is built in. Normally when attaching a hose to an MFL connection you will use a swivel nut with barb.

Beer Nut Thread

Beer Nut Thread - OK, I have saved the most confusing for last. A beer nut is used for multiple connections on a draft beer system including two on a beer coupler, one on the back of a beer shank and it is also used when connecting GovReg secondary beer regulators. So, what size is it? It is normally called a ? beer nut or ?-14. However, it is really 29/32-14 and it is also called ? BSP. Three names for the same thing? Well yea, basically, but you can just call it a beer nut.

Conclusion

So this covers the vast majority of threads or connections you will see used in draft beer systems. It can be confusing at times, but the same threads tend to be used in the same places so it does not take too long to determine what to use where. Still confused about something? Email us at [email protected] or call us at 325-356-5204. We are happy to help.