Draughtflow cans

Fred:

Mechansim is quite simple, before the beer is placed in the can (or bottle or keg), it is carbonated and nitrogenated to precise levels in a holding tank. Here in the USA this tank is known as a bright beer tank. As the empty cans/bottles move down the conveyor toward the filler, a special machine places a widget in each can/bottle. The widget is esentially a hollow plastic sphere or other shape, and other than holding the widget in place in the can I don't believe that the shape has any major role. However the secret is that just before the widget is placed into the can a laser cuts a hole of a precise diameter in the widget. The can is then filled and sealed in the conventional manner.

After sealing, the higher pressure in the can relative to the inside of the widget results in the widget filling with the beer until the pressure inside the widget reaches an equilibrium with the rest of the can. Things then remain stable until the can is opened. When the can is opened, the pressure in the bulk of the liquid falls, faster than that of the liquid inside the widget. As a result of this differential pressure, the liquid in the widget squirts out through the orrifice, this sets up shear forces that strip the nitrogen from solution in exactly the same way as the restrictor plate is a "stout faucet" does. The nitrogen forms the dense creamy bubbles that give the characteristic creamy head.

As for making all beers taste the same, I believe that this is a side effect of the niotrogenation. My experience is that the nitrogen tends to strip hop bitterness from the liguid into the head. I know this sounds gross, but use your finger to scoop out some of the head and taste it, typically it will be bitterer than the liquid, hence the beer will have that same relatively bland smooth taste.

Iechud Da - Cwrw42

That was interesting! Thanks!

So what's the reason that a laser must cut a hole just prior to insertion into the can? I don't see any explanation for that. If the other things you say are true, then the "hole" can be manufactured at the same time the rest of the widget is - no need for any laser on the filling line.

: Fred:

: Mechansim is quite simple, before the beer is placed in the can (or bottle : or keg), it is carbonated and nitrogenated to precise levels in a holding : tank. Here in the USA this tank is known as a bright beer tank. As the : empty cans/bottles move down the conveyor toward the filler, a special : machine places a widget in each can/bottle. The widget is esentially a : hollow plastic sphere or other shape, and other than holding the widget in : place in the can I don't believe that the shape has any major role. However : the secret is that just before the widget is placed into the can a laser : cuts a hole of a precise diameter in the widget. The can is then filled and : sealed in the conventional manner.

: After sealing, the higher pressure in the can relative to the inside of the : widget results in the widget filling with the beer until the pressure inside : the widget reaches an equilibrium with the rest of the can. Things then : remain stable until the can is opened. When the can is opened, the pressure : in the bulk of the liquid falls, faster than that of the liquid inside the : widget. As a result of this differential pressure, the liquid in the widget : squirts out through the orrifice, this sets up shear forces that strip the : nitrogen from solution in exactly the same way as the restrictor plate is a : "stout faucet" does. The nitrogen forms the dense creamy bubbles that give : the characteristic creamy head.

: As for making all beers taste the same, I believe that this is a side effect : of the niotrogenation. My experience is that the nitrogen tends to strip : hop bitterness from the liguid into the head. I know this sounds gross, but : use your finger to scoop out some of the head and taste it, typically it : will be bitterer than the liquid, hence the beer will have that same : relatively bland smooth taste.

: Iechud Da - Cwrw42

:> How do the plastic inserts (widgets?) in draughtflow cans work? Also :> is it an additional function of these things to make all beers taste :> the same or is it just me? :>

:> Thanks.

It's a Goldfinger Industries filler.

If so, wouldn't "laser" need to be in quotes???

snip

An excellent explanation, and I understood it. Thanks :-)

Joe:

Good follow up question. To be absolutly certain of the answer I would need to dig through some files, however I seem to recall that there were two reasons for making the hole with a laser just before the widgets are put in the can.

1. The widgets are blow moulded using an inert gas, probably nitrogen, if the hole was get earlier, the nitrogen would diffuse out with the result that air and oxygen would enter the sphere. This oxygen would subsequently end up in the beer and cause oxidation. As you probably know, brewers are obsessive about eliminating oxygen pickup during packaging. So waiting until the last possible moment to make the hole is a way to limit oxygen pick up in the package.

1. I also believe that the diameter of the hole was crucial, and they found that the best way to get a consistent diameter was using a laser to cut the hole.

Hope this answers your questions - iechyd da - Cwrw-42.