5mm tubing

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Permalink Reply by David M on July 23, 2015 at 3:21pm

Sure will take some tonight or tomorrow (as may not have time tonight) and post.

Had a look at doing it inline but prefer using a wand in the fermenter for the following reasons.

I find that the temp coming out of the counter flow chiller is always higher than I pitch so I chill the fermenter to the right temp before I pitch - especially with lagers.

O2 saturation increases as temp decreases. If I oxygenated before I chilled the ability for the wort to absorb o2 is less and any lag time before pitching allows the o2 to come out of solution. It also provides a nice oxygenated breading ground for other things in the time between. I oxygenate just before I pitch.

You normally run the o2 for a short period into the fermenter and the general guides available (flow\time) give a good enough o2 ppm result. In the fermenter there is plenty of wort in contact with the stone for good transfer - I move my wand around a bit.

Doing it inline would reduce the amount of wort in contact with the stone if you are just providing oxygen for a short period. The other option is less o2 flow for a longer period. This always seemed more error prone for me unless I could precisely meter a very slow known flow - o2 is great but you don't want to over or under oxygenate.

Commercial guys wouldn't have this issue as their flow transfer rates are higher.

I tried a 1-5L/min flow meter and valve and its ok but find it too inaccurate at the low end of its range. I think it's 1L/min is more like 2L/min and I have too much bubbling to the surface. Have just got a 0.25-1.5L/min one and will see if that is better. I target a 1l/min flow rate which is what most of the scenarios I have read are based on.

You would also need to install the stone inline before any flow restriction in your cooling system as if the line is not full of liquid around the stone with good liquid to stone (gas) contact and the flow slightly pressurised  you will be loosing lots of o2 as only a small amount will be absorbed by the wort and the rest would just escape.

A wand is also great to oxygenate starters too.

Will post pics in the next day or so - be warned there is duct tape involved. It is just a flow meter tapped to the gas bottle with a hose and wand connected. Once I have it right I will build a mount and make it more permanent.

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Permalink Reply by Daniel Ashman on July 24, 2015 at 9:48am

Hi David,

Thanks for taking the time to reply.

All the points you make are valid so on second thoughts maybe I will just oxygenate in the fermenter rather than in-line.

One thing I'm unsure of is what is the batch size for the recommended 1L/min for 1min. I'm aiming for 30L batches so I'm assuming I'd need a bit more.

Also as far as I can tell they recommend a high oxygen concentration for higher gravity beers but how much? It would be really useful if there was a rough formula for how long to run the oxygen for a given batch size and gravity at the flow rate of 1L/min. I realise it depends on how much is actually absorbed but a rough guide would be useful. 

Permalink Reply by Peter Smith on June 5, 2015 at 2:10pm

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Permalink Reply by David M on June 11, 2015 at 3:12pm

Just got some Guest fittings from Marc at Pacificool in Pakuranga. Good prices and good service - knows his stuff and supplies a lot of pubs and brewers in NZ and the island. Will do mail order if you want Sean. www.pacificool.co.nz

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