Silicone hose

[Ski]

What kind of hose do you use/recommend?

Like many, I use silicone hose for its food-grade high-temperature rating. However, it has a terrible O2 permeability rating: 7961E10 cm3
*cm/(s*cm2*cmHg). I estimate a 1-metre, 21mm OD hose could permeate almost 700 cc of O2 during a 2-hour mash. Of course, it still has to dissolve into the wort passing through the hose, and I've no idea how much will actually be absorbed.
I'm using about 2 metres of hose total for pumped circulation of the wort during mash. Is this a weak point, is it covered by the SMB addition? Should we be using a different hose material?

Thanks - ski

[Owenbräu]

I haven't checked your calculations, but I'll trust your numbers are good. It's likely that the tubing is contributing oxygen, and may be one reason why we see more color and loss of peak flavor the longer we mash. Without a perfect system, it would be tough to isolate and measure oxygen pickup from just the tubing. As you're building your system, it is essential to have the flexibility and adaptability that silicone tubing allows. Once you have your system where you want it, then hard piping is best.

[Bryan R]

I have very nearly a closed recirculating system using some silicone tubing. I only have to use 55mg/l of NAmeta, and still have 25mg/l(+-)left over into the boil. So that mean my system only uses 30mg/l(+-) for the dough in and 3 hour mash. In a non active o2 mitigation system, I would think this would be important, but that's why we use NAmeta.

[Ski]

Thanks Ancient and Bryan. Very comforting to know that all the SMB is not getting consumed by excessive O2 ingress. I've emailed a request to a few suppliers to see if there is anything out there that would be a better alternative than silicone. Solid tubing is ideal but in my case flexible is more suitable because I break down and store my system after each brew. I'll post the calculations later (on a train at the moment) because it seems they are too pessimistic.
-Ski

[narcout]

I wonder if something like this would be better?

https://www.morebeer.com/products/high- ... 12-id.html

Or

http://www.northernbrewer.com/1-2-id-th ... tic-tubing

I'm in the process of incorporating a pump into my system and am trying to decide which tubing to use.

[Ski]

Hi narcout - thanks for the tip. Loving the spec of the EJ Beverage one at morebeer. I have some of EJ's tubing connecting keg to tap, and it's excellent stuff. O2 barrier, no pvc. I also use it on the gas side, so no O2 permeates in on the gas side either. I didn't know they made it for hot-side applications too. This is a great find! Just what I was looking for.
Thanks again - Ski

[Ski]

Oh and forgot to mention, it's completely flexible, not like the hard glass-lined tube you normally get for beer line. -Ski

[Ski]

As promised, here are my calculations.

Tube Surface_Area = pi*Diameter*Length

Permeation Transfer = P* Surface_Area*Time*delta_Pressure/Thickness
where P is the Permeability constant of the material (dimensioned in an amazing variety of ways).

Tube Length 100.000 cm
Inner Diameter 1.270 cm
Outer Diameter 1.905 cm
Average Diameter 1.685 cm (as a rough approximation, take the average diameter)
Surface Area 529.358 cm2 ("average" surface area for our purposes)

Thickness 0.3175 cm
Time 7200.000 secs
Pressure 76.000 cm Hg


Transfer 912,330,380.34 cm3 per unit permeability P for this hose dimension over 2 hours.
assuming units of P are cm3.cm/(cm2.sec.cm-hg) (volume of STP gas * cm thickness per (cm2 surface area * seconds exposure * cm mercury pressure differential))

Unclear is whether the P factor applies to pure O2 gas or atmospheric O2 (21% - in which case transfer numbers are about 1/5 of pure O2).
Unclear is whether diffusion into the liquid inside the tube should also be considered, or if permeation dominates.

Material P-factor Transfer
Silicone 7961.000E-10 726.306 cm3 over 2 hours.
EJ_Bev 4.480E-10 0.408 cm3 over 2 hours.

This is based on Cole-Parmer permeability factors for silicone, and EJ Beverages claim that their material is 70% better than PVC.
If all this is true, and I haven't complete screwed up the sums, then I'd say we have a winner! Well done, narcout!

I would welcome any corrections or clarifications to my math. Bryan's experience suggests that the measured ingress of O2 is much less than predicted by this model. Nonetheless, the simple comparison of silicone to EJ's tube suggests we may have a contender for hose of the year!
Thanks - Ski