Hands on Review: Ferroday Stainless Steel Carbonation Cap for PET Bottles & Draft Line Cleaning Builds

This is a hands on look at a Stainless Steel Carbonation Cap by Ferroday along with some information about what these are used for and some related build projects.

What are stainless steel carbonation caps used for?

  • PET Bottles as Growlers: These are generally intended to convert 1L and 2L bottles to growlers.  Fill up a 1L or 2L PET bottle with your favorite homebrew.  Put one of these on (purge the headspace by squeezing if you want to) and then pressurize for transport.  This should help to reduce oxygen pickup and maintain carbonation levels.
  • Fine tune or rapidly carbonate beer: You can also use this cap to rapidly carbonate beer.  Same process as for transport, just set your regulator to the proper pressure and shake or agitate the PET bottle to help introduce CO2.  Or hook it up to CO2 and let it sit in you kegerator.
  • Draft Line Cleaning Projects:  I have developed three draft line cleaning projects using similar SS Caps – Build A Recirculating Draft Line Cleaning Pump | Mark II Keg and Carboy Cleaner Draft Line Cleaning Pump ConversionBuilding a Simple Ball Lock Draft Line Flushing Setup


Check Current Price, Specs & Availability:

Universal Liquid and Gas Carbonation Caps

The really big question that needs to be answered, if you want to build a draft line cleaning setup using one of these, is whether or not it is universal.  Ball Lock Kegs have gas and liquid posts along with corresponding QDs.  Black goes on liquid, grey or white goes on gas.  They ARE NOT interchangeable.  The beauty of some stainless steel carbonation caps is that they are universal, meaning they can accept both gas and liquid QDs.  That’s very important for draft line cleaning builds because we want to connect a liquid QD to this.  The problem is, not all stainless steel carbonation caps are universal.

Hands on Review of Ferroday’s Stainless Steel Carbonation Cap

The front of the package.  Nice little zip top bag.  Handy for storage when it’s not being used so you can keep the carb cap stored along with the included replacement o-rings.Back of the package.  If you zoom in you can see the ASIN number on the labelWhat came in my package.  The stainless steel carbonation cap and four replacement o-rings.A look at the underside.  I would characterize this as having a high build quality.  It looks nice and feels hefty.  More on that later.A side view.  Although it’s a little blurry you can see Ferroday etched on the sideInstalling this on a 1L PET bottle.  Note that the top is designed so you can use a wrench to get some additional leverage when tightening.This a a slightly arbitrary comparison, but the carb cap on the left is the first one I used to put together my draft line builds.  It was sourced from AliExpress and took forever and a day to arrive 🙂 – If you look just above the barb (click to zoom) you can see the left one (AliExpress) is slightly pitted and the right one (Ferroday) has a nice, smooth stainless steel.  Not a huge deal either way, but this is an illustration the build quality I talked about previously.I completed a pressure test using a digital version of my Spunding Valve Build.  The nice thing about the digital version is the .1 (1/10th) PSI resolution that it offers.  That means you can quickly and easily spot leaks.  This held steady at 22.5 to 22.4 PSI for a long time.I talked about the heft and build quality of this cap.  Here it is being weighed on my Model AWS-100 Digital Gram Scale – Hands on Review.  It weighed in at a hefty 96.31 grams.  By comparison, again, slightly arbitrary, the AliExpress cap was 91.78 gramsMy big question was… Is this a universal stainless steel carbonation cap?  I picked up this combo of gas and liquid ball lock qds to try out – OneBom Ball Lock Disconnect, Gas & Liquid Corny Keg Fittings, MFL 1/4’’ Threaded with 5/16’’ Stainless Steel Barbed & Hose Clamp (Ball Lock Kit)This gas qd fit just dandyand… the ball lock qd fit just dandy!  The carb cap I received is truly universal!


The general availability of stainless steel carbonation caps at reasonable prices has been a big improvement since my first days of homebrewing.  When I started these style caps were the only ones that were available.  I had a hard time getting a good seal on mine.  Stainless steel is a big upgrade in and of itself add on universal gas and liquid capability along with a barb and generally reasonable prices and you’ve got a big improvement when it comes to carb caps.

This particular model is a well built and the one I received is universal in that it accepts both gas and liquid QDs.

Related: Fun with Carbonation Caps!

Our Line Cleaning Builds!

Related Projects!

Also Consider:

ball lock jumperStainless Steel Ball Lock Jumper with Food Grade Silicone O-Rings: Allows you to connect multiple ball lock runs to clean multiple lines and taps at the same time. Works with both liquid and gas QDs.  Stainless Steel Ball Lock Jumper – via Valuebrew – An easy add-on… food grade o-rings, featured in our Keg Rebuild Post

This article contains affiliate links. We may make a small percentage if you use our links to make a purchase. You won’t pay more and you’ll be supporting Homebrew Finds and more content like this. Thank you for your support!

More Homebrew Finds!

Recent Deals!

10 Most Recent Homebrew Resource Posts & How-To’s!

This post may contain affiliate links. We may make a commission when you use our links. This will never cost you extra. Thank you for supporting Homebrew Finds!

Make sure the components you use are compatible and rated for your intended application.  Contact manufacturer with questions about suitability or a specific application.  Always read and follow manufacturer directions. tag:lnksfxd review:ferrodaycarbcap tag:tpr

Leave a Reply