Brewnundrum

Oxygen Flow Meter for a disposable oxygen tank

Years ago Liquid Bread came out with what was probably the first oxygenation setup for homebrewers that included a tank of Oxygen (Bernzomatic), a regulator, hose and a 0.5 micron stone. I still have all of the reusable parts to that kit over a dozen years later.

While I’ve read how much oxygen ppm a brewer should try to achieve, it was impossible to calculate if my method was helping me achieve my goals. I’d open up the valve until I was at a flow rate where the bubbles were gently breaking the surface of the wort, but it was always a guess if that was the right way to do it.

While reading Yeast by Dr. Chris White and Jamil Zainasheff I came upon some solid info. on how to achieve various levels of oxygenation so long as I could ensure my flow rate was 1 liter per minute (lpm).

Unfortunately, the regulator from Liquid Bread is rudimentary and couldn't be modified to attach a quality flow meter. I did not want to use a cheap inline flow meter which would require me to grow an extra set of hands to keep it hanging vertically, so I decided to build my own setup from scratch.

The parts:

• Pediatric Flow Meter
• Regulator for a Disposable Oxygen Tank for jewelers
• DISS 1240 to 1/8” npt Adaptor
• 1/8 npt female to male Adaptor
• Plastic Toilet Flange
• Gas Line Teflon tape

The flow meter scale – 1 lpm was my target….easy to read on this scale! When the oxygen is flowing, the ball hovers and reading the flow rate is extremely simple. The middle of the ball is where I take my reading.

The old "dumb" regulator and the killer new one I built. 

This is the special DISS to npt adaptor from Bay Corp. with the butt end of the flow meter to the left and the standard barb attached on the right.

This is the 1/8” npt female to 1/8” npt male adaptor joining the flow meter to the regulator. The regulator out flow has a male reverse flare fitting.

Unfortunately, I could not locate a female reverse flare to 1/8” npt male adaptor, but the adaptor I used tested negative for leaks. Use the right adaptor instead if you can find one.

The entire setup with the new toilet flange base stabilizes the oxygen tank

and makes operation hassle free.

Where to get the parts and where to use in the build: 

• From a seller on eBay I bought a Pediatric Flow Meter for $22.00. I highly recommend using a pediatric flow meters because the scale is from 0 to 3 lpm, so measuring my goal flow rate of 1 lpm is easy. The standard flow rate meters I saw for sale have a scale that does from 0 to 8 lpm, so the pediatric meter is much easier to read.
• From a seller on Amazon I bought a Regulator for a Disposable Oxygen Tank normally used in the jewelry business for $33.00. It comes with a threaded connector, so I would be able to attach the flow meter.
• Bay Corporation makes a DISS 1240 female to 1/8” npt female adaptor (P/N  1242-8). This is needed for the outflow side of the flow meter so I could then attach a 1/8” npt male to 1/8” barb connector. This special adaptor is hard to find. It’s only available from many medical supply companies. I bought mine for $8.92 from Medsurge.com
• I also bought a 1/8” npt female to 1/8” npt male adaptor to attach the flow meter to the tank regulator. The threads on the regulator are actually 1/8” male reverse flare type. This is nearly identical to npt. The tpi is the same, but the taper is different between the two types of pipe. The reverse flare has nearly no taper at all, so I had to use 2 wraps of gas line Teflon tape and screw the adapter all the way on and give it a good crank to ensure it was down to the narrowest part of the adaptor and was properly sealed. I successfully tested and passed the seal between the fittings using a soapy water test like you would use to find a leak in a bicycle inner tube. Please use the correct female reverse flare to male npt adaptor if one is available so you can be confident your oxygen isn’t leaking out during use.
• In the end, this setup gives me two valves where I’d prefer to have one. Once the tank regulator is opened up, it’s easy to set the flow rate using the valve in the flow meter.
• Having the flow meter stick out caused the tall, skinny oxygen tank to be unstable and it wanted to fall over pretty easily. Luckily, a Plastic Toilet Flange from Lowe’s has an ID of 3” which is a perfect fit for the disposable oxygen tank which is 2.9” diameter. Cost was just under $5.
• I used Gas Line Teflon tape for all fittings. Oxygen is far too flammable to mess around with, so I played it safe.

Total cost for this custom made flow meter for disposable tanks was just over $70. That’s about triple what a “dumb” tank regulator from a homebrew shop costs ($19.99 at Williams Brewing), but without knowing the flow rate it’s is very hard to consistent when oxygenating your wort for those big beers that need more than 8 ppm.