[mrcceo]

I'm not saying a short tube won't work, but the added length is a nice safety factor. Just stands to reason that the more surface area your filter has, the faster it will allow the runnings to flow and the less likely it will clog.

But why wouldn't the wort just flow in one side and out the other?  Why would it follow a perforated tube with so much open surface area?

Because the grain bed compresses forming resistance to backflow.

[denny]

Hmmmmm....gonna have to think about that.

[Mikey]

I'm not saying a short tube won't work, but the added length is a nice safety factor. Just stands to reason that the more surface area your filter has, the faster it will allow the runnings to flow and the less likely it will clog.

But why wouldn't the wort just flow in one side and out the other?  Why would it follow a perforated tube with so much open surface area?

Good point, but the majority of it will take the path of least resistance and that's down the middle of the tube.

[beveragebob]

I'm with DC on this one. I go by handfulls usually 3-5 has always worked for me

[denny]

I'm not saying a short tube won't work, but the added length is a nice safety factor. Just stands to reason that the more surface area your filter has, the faster it will allow the runnings to flow and the less likely it will clog.

But why wouldn't the wort just flow in one side and out the other?  Why would it follow a perforated tube with so much open surface area?

Good point, but the majority of it will take the path of least resistance and that's down the middle of the tube.

I've done an experiment where I fill the cooler with water, and the start lifting the braid from the water by the end farthest from the outlet.  The flow rate remains unchanged.  This says to me that the braid length doesn't make all that much difference.  Is this an invalid test?

[mrcceo]

I'm not saying a short tube won't work, but the added length is a nice safety factor. Just stands to reason that the more surface area your filter has, the faster it will allow the runnings to flow and the less likely it will clog.

But why wouldn't the wort just flow in one side and out the other?  Why would it follow a perforated tube with so much open surface area?

Good point, but the majority of it will take the path of least resistance and that's down the middle of the tube.

I've done an experiment where I fill the cooler with water, and the start lifting the braid from the water by the end farthest from the outlet.  The flow rate remains unchanged.  This says to me that the braid length doesn't make all that much difference.  Is this an invalid test?

That test is not representative of the conditions when conducting a mash.  I would imagine you would have to conduct a series of tests with different length braids and different mashes which incorporated varying amounts of wheat and rye and then measure the volume/rate of flow from the valve in order to be conclusive.

[redbeerman]

You're right Denny.  It won't make a difference, all the fluid passes through the hole in the wall.  Gravity brings it to the bottom of the container.  A longer braid may help as far as clogging goes, though, as the grain has a larger surface area to compress.  With a short braid or for the sake of arguement just a screen in a fitting in the hole, if the grain is compressed against it, it has a better chance of becoming clogged.

[bluesman]

You're right Denny.  It won't make a difference, all the fluid passes through the hole in the wall.  Gravity brings it to the bottom of the container.  A longer braid may help as far as clogging goes, though, as the grain has a larger surface area to compress.  With a short braid or for the sake of arguement just a screen in a fitting in the hole, if the grain is compressed against it, it has a better chance of becoming clogged.

+1

The flow of wort will be most affected by the limiting factor which is the size or diameter of the hole from which it is flowing through in some cases.  In other words if you had a 30" braid and a 1/8" hole the flow would be restricted mostly by 1/8" hole. 

The question in my mind is "where is the bottleneck" in the system.  The grain bed...the braid...the outlet dia....or all of the above.

 The short answer is that they are all dependent upon each other to do their job but ultimately one will be a bottleneck per say.  One must look at the system from a fluid dynamics perspective and make the assessment.

[mrcceo]

You're right Denny.  It won't make a difference, all the fluid passes through the hole in the wall.  Gravity brings it to the bottom of the container.  A longer braid may help as far as clogging goes, though, as the grain has a larger surface area to compress.  With a short braid or for the sake of arguement just a screen in a fitting in the hole, if the grain is compressed against it, it has a better chance of becoming clogged.

That's exactly what were saying regarding the length of the braid.  A longer braid is less likely to clog because of the increased surface area therefore less likely to cause a stuck sparge.

[tschmidlin]

A longer braid is less likely to clog because of the increased surface area therefore less likely to cause a stuck sparge.

Yeah, in Denny's experiment the limiting factor is the outlet hole, the braid is no real impediment at all if there's just water in the mash tun.  For a mash though, bits of flour or wheat/oats from the grist can clog a braid depending on the hole size.  So you'd need to do the experiment with consistent grist and different length hoses to figure it out for sure, and then vary the grist with the hoses as well.

Hose length obviously does make a difference theoretically, but it might not make a difference in practical terms depending on your mash conditions.  It sounds like it makes no practical difference for Denny's typical mashes.

[mrcceo]

A longer braid is less likely to clog because of the increased surface area therefore less likely to cause a stuck sparge.

Yeah, in Denny's experiment the limiting factor is the outlet hole, the braid is no real impediment at all if there's just water in the mash tun.  For a mash though, bits of flour or wheat/oats from the grist can clog a braid depending on the hole size.  So you'd need to do the experiment with consistent grist and different length hoses to figure it out for sure, and then vary the grist with the hoses as well.

Hose length obviously does make a difference theoretically, but it might not make a difference in practical terms depending on your mash conditions.  It sounds like it makes no practical difference for Denny's typical mashes.

+1

[denny]

A longer braid is less likely to clog because of the increased surface area therefore less likely to cause a stuck sparge.

Yeah, in Denny's experiment the limiting factor is the outlet hole, the braid is no real impediment at all if there's just water in the mash tun.  For a mash though, bits of flour or wheat/oats from the grist can clog a braid depending on the hole size.  So you'd need to do the experiment with consistent grist and different length hoses to figure it out for sure, and then vary the grist with the hoses as well.

Hose length obviously does make a difference theoretically, but it might not make a difference in practical terms depending on your mash conditions.  It sounds like it makes no practical difference for Denny's typical mashes.

+1

Thanks for the discussion and your thoughts, guys.  When I was conducting my initial braid length tests years ago, it was in a real mash and that's where I found the braid length made no difference for me.  But as Tom points out, YMMV.

[mrcceo]

You're welcome Denny. 
Nothing like a little lively debate.

[1vertical]

Ok,
My $.02...........I use enough hulls to cover the bottom of the cooler to the depth of the braid.  I wash the hulls with
the mash tun preheat water in the cooler because they are DIRTY for sure.  Uh sometimes I have slow runoff
even with this.  Braid is most of the length of the cooler (2/3) and 1/2 inch diameter.  My bulkhead may be the culprit.

[Beertracker]

I typically use a "couple" of handfuls when using wheat or rye malt in excess of 50%. Approx. < 2-3%?