Chronic Foam Issue

I was going to question the flow control on the tap too, the picnic tap seems like a good test.

The other thing I was thinking about is the cleanliness of the tap. I had a beer that kept pouring foaming once so I took the tap apart and there was some nasty gunk in it. It's embarrassing to admit but I scrubbed it all clean and no more foam.

Also, check this out on youtube at the 1:45 mark, could this be your issue?

[ame]https://www.youtube.com/watch?v=KIlj1Bq3BUc[/ame]

David

djonesax said:

Anyway, your system works for you and thats great, I'm not trying to start an argument. I'll take a video of the pour later to show what I mean.

Click to expand...

I agree that if your system works the way you want, you have little reason to change it. But the reasoning behind WHY it works is a bit flawed, as unfortunately the internet is full of misleading information regarding resistance in general. As I mentioned earlier, line resistance is completely dependent on flow rate. This means that all of these numbers that you (and others) are quoting like "5/16 OD tubing which has a resistance of about .5 PSI" is completely false as a generalization as a key piece of information (the flow rate) is missing. You cannot say that a given type of line has a specific number as a resistance without taking flow rate into account; it's just incorrect to say so. You have to account for the flow rate, and that flow rate has to be ~1gal/min in order for those quoted resistance numbers to mean anything at all. Otherwise those numbers are complete garbage.

Without going too deep into fluid dynamics (as even I don't have an expert level grasp of it), here's a basic formula for fluid resistance (R):

R = (change in pressure) / (flow rate)

Therefore, without factoring in the flow rate, you cannot calculate resistance.

Furthermore, to calculate the "change in pressure" (we'll call this deltaP), you actually need the flow rate as well. The formula to calculate pressure change is:

deltaP = (128uLQ)/(pi*(d^4))

where:
u = viscosity
L = line length
Q = flow rate
d = line diameter
pi = the mathematical constant Pi.

So as the line length increases, flow rate decreases, which actually causes the change in pressure (deltaP) to decrease. Plugging this in to the above basic formula for line resistance, if deltaP is decreasing and flow rate is decreasing (both due to lengthening the line), then the ratio of deltaP/Q (i.e. resistance) will decrease exponentially. Hence "line resistance decreases exponentially as flow rate decreases".

In the most simple terms I can think of, consider the following equation:

x = 2 + y


What you are basically doing by saying that 3/16" line always has a resistance of 2psi/ft, is the same as saying that in the above equation, "x" is always equal to 6. You are completely ignoring that a part of the equation "y" is variable, and are treating it as a constant. The only way for x=6 is if y=4; there is absolutely no other way to make it true. Similarly, the only way for 3/16" line to have a resistance of 2psi/ft, is to have a flow rate equal to 1gal/min. If that flow rate changes, then the resistance cannot be "2psi/ft".


For the record, I'm not trying to argue either. I just want to help prevent the spread of misinformation regarding these flawed ideas of how resistance and line balancing work. I hear too many people saying things like "too long of lines will cause problems/foaming/etc", which couldn't be further from the truth. Sure, eventually you'll reach a length where the pour is unbearably slow. But changing your lines from 5' to 10' for any reasonable serving pressure >10psi will have minimal effect on flow rate.

I'm not trying to be an expert here, just explain things as much as I comprehend them. Perhaps someone more knowledgeable in this area can contribute better examples. I have a degree in mathematics, but fluid mechanics delves more into the realm of physics, of which it's been a while for me.

djonesax said:

I was going to question the flow control on the tap too, the picnic tap seems like a good test.

Also, check this out on youtube at the 1:45 mark, could this be your issue?

Click to expand...

Ha, instead of posting that last long post, I could have just as easily referenced the video you posted. When he turns the flow control up, he is increasing resistance (the same way that adding line length would), and it causes no foaming problems whatsoever. Conversely, it decreases foam production. This disproves the theory you posted in the other thread you linked to previously, where you stated "If you have 10' of line and 13psi, and its trickling out, that will cause foam too."

djonesax said:

I was going to question the flow control on the tap too, the picnic tap seems like a good test.

The other thing I was thinking about is the cleanliness of the tap. I had a beer that kept pouring foaming once so I took the tap apart and there was some nasty gunk in it. It's embarrassing to admit but I scrubbed it all clean and no more foam.

Also, check this out on youtube at the 1:45 mark, could this be your issue?

https://www.youtube.com/watch?v=KIlj1Bq3BUc

David

Click to expand...

Thanks for the suggestions and the vid! Yeah, disassembling and thorough cleaning was the first thing I tried. No dice so far

Colt85 said:

Thanks for the suggestions and the vid! Yeah, disassembling and thorough cleaning was the first thing I tried. No dice so far

Click to expand...

Do you have or can you get another faucet to see if you get the same foaming?

MagicMatt said:

Ha, instead of posting that last long post, I could have just as easily referenced the video you posted. When he turns the flow control up, he is increasing resistance (the same way that adding line length would), and it causes no foaming problems whatsoever. Conversely, it decreases foam production. This disproves the theory you posted in the other thread you linked to previously, where you stated "If you have 10' of line and 13psi, and its trickling out, that will cause foam too."

Click to expand...

Thanks for that explanation, I get what you mean about the flow rate now and how its related to the resistance.

The thing that doesn't make sense to me and maybe you can explain this. I get a 10.45 second pint with 5' and when I add that flow rate into the calculator you mentioned, it said I needed a 9.2' line to get the same flow rate that I am already getting with 5'. It seems like that might mean that 5' is all I really need and the extra 5' I added has little affect since I have already reduced the flow rate to a rate where there is little resistance. BUT, I fiddled with the calculator and I found that it thinks that with a 5' line I'd have a flow rate of 7 second pints which isn't what I have. So my real world example and the calculator don't jive.

Also, just to show what I was talking about. I took 4 crappy videos.

10 Foot Warm Tap
10 Foot Cold Tap
5 Foot Warm Tap
5 Foot Cold Tap

In the 10 Foot Warm Tap video you can see what I mean by its trickling out. It eventually fills the tap and pours right but the initial turbulence still seems to produce more head than desired. The 5 Foot Cold Tap video produces the least amount of head.

David

View attachment 10footWarmTab.MOV

View attachment 10FootColdTap.MOV

View attachment 5FootWarmTap.MOV

View attachment 5FootColdTap.MOV

Thanks for the videos. For what it's worth, the 10 second pour looks perfectly acceptable and appropriate for a homebrew installation. You say it trickles, I say nay. I'm assuming the different levels of head between the two (10 and 5 seconds) was because they are different beers. But if you play them side by side, there's virtually zero change in the amount of time it takes to reach the same level.

So while it may look different to you coming out of the tap, there's no real noticeable change in pour speed (even though you would think that doubling your lines would double your resistance).

Colt 85. I looked at the tap on Amazon and it indeed looks to be flow control. Your in the clear. However I've never used one so I can't comment on it much. Not sure how the creamer taps work either. I just know they look similar with the valve on the side. Good luck!

MagicMatt said:

Thanks for the videos. For what it's worth, the 10 second pour looks perfectly acceptable and appropriate for a homebrew installation. You say it trickles, I say nay. I'm assuming the different levels of head between the two (10 and 5 seconds) was because they are different beers. But if you play them side by side, there's virtually zero change in the amount of time it takes to reach the same level.

So while it may look different to you coming out of the tap, there's no real noticeable change in pour speed (even though you would think that doubling your lines would double your resistance).

Click to expand...

Its hard to tell in the video but the 10 foot line is definitely a couple seconds slower for a full glass. I timed them on my phone last night with the same tap and beer

We'll have to agree to disagree on the length because I still think its a little too long since it just doesn't seem to have enough flow speed to fill the tap like the shorter line. Look at the picture to see what I mean and see how the turbulence is creating more head. I will admit that length is not as as drastic a difference as I was expecting but the previous shorter line definitely poured better in my opinion. Later on tonight I'll shorten that 10' line to 8' and see if I like it better.

Thanks,

David

Rockn_M said:

Do you have or can you get another faucet to see if you get the same foaming?

Click to expand...

Picnic tap is in the mail, will report back

Nice tower but I think part of the problem is how it is cooled. To test this, pour a pint of seltzer and take the temp. Then pour another and take the temp. Keep doing this until you get the same temp on two pints. This will tell you how good your tower cooler works and the temp of the beer in the other keg is. Now with commercial kegs you have to know how many volumes it was carbed at e-mail the brewery and ask. Now you have the only two things you need to balance your system. Use this chart to set the psi. http://www.kegerators.com/carbonation-table.php Forget Line calculators there useless for a home system. They are for commercial systems with remote draw. Now if you have your keg in the basement and tap in your bedroom on the second floor then it will come in handy. Line length is used to control the flow only not to balance your system. Now if your system is balanced I would check the Coupler. On a D Coupler it could be the check ball #2 is stuck. Remove it you don’t need it if your shutoff has backflow preventer on it. Or your Probe Seal #4 is bad and letting co2 from the head space get into the beer line.

http://www.micromatic.com/draft-keg-beer/keg-taps-couplers-pid-7485E.html

what shanks are you using, and do they have elbows for the tubing? Do you have any spare faucets that you can check with?

I don't want to insult you, but did you check to make sure that the tubing is truly 3/16" ID?

Have you fully dissasembled the sanke coupler and checked for debri, cleaned it, etc?

PapaO said:

Nice tower but I think part of the problem is how it is cooled. To test this, pour a pint of seltzer and take the temp. Then pour another and take the temp. Keep doing this until you get the same temp on two pints. This will tell you how good your tower cooler works and the temp of the beer in the other keg is. Now with commercial kegs you have to know how many volumes it was carbed at e-mail the brewery and ask. Now you have the only two things you need to balance your system. Use this chart to set the psi. http://www.kegerators.com/carbonation-table.php Forget Line calculators there useless for a home system. They are for commercial systems with remote draw. Now if you have your keg in the basement and tap in your bedroom on the second floor then it will come in handy. Line length is used to control the flow only not to balance your system. Now if your system is balanced I would check the Coupler. On a D Coupler it could be the check ball #2 is stuck. Remove it you don’t need it if your shutoff has backflow preventer on it. Or your Probe Seal #4 is bad and letting co2 from the head space get into the beer line.

http://www.micromatic.com/draft-keg-beer/keg-taps-couplers-pid-7485E.html

Click to expand...

Thanks for the suggestions PapaO. I've done the first bit, first pour is around 42, subsequent pours quickly even out to ~38. Not ideal but I believe my problems are much greater than tower cooling as I can fill pitcher after pitcher of cold foam.

Ok, I'll find out about CO2 in the commercial keg. So, say it's carbed to 2.5 volumes, then I'd set the psi to ~10 since I'm at 38 degrees? This is currently where I'm at temp/psi-wise.

I've already disassembled and cleaned the coupler a few times but I'll try again. I'm using this one, brand new: http://www.amazon.com/gp/product/B002UZUSIM/?tag=skimlinks_replacement-20

Are some brands more reliable than others? Think it's worth replacing the whole thing?

gnef said:

what shanks are you using, and do they have elbows for the tubing? Do you have any spare faucets that you can check with?

I don't want to insult you, but did you check to make sure that the tubing is truly 3/16" ID?

Have you fully dissasembled the sanke coupler and checked for debri, cleaned it, etc?

Click to expand...

I'm using these shanks: http://www.amazon.com/dp/B00829HNWE/?tag=skimlinks_replacement-20

They've got barb fittings and I've got line secured with hose clamps.

No insult taken! Anything's fair game at this point. Yes the line is 3/16 ID.

I've disassembled and cleaned the coupler twice now with no change in performance. I've got a picnic tap on the way to test weather the faucet is the culprit.

What is the sharpest bend that the tubing has to make? If it is pinched at any point, it could cause the symptoms that you describe.

Looking at your pictures, the highest likelihood of pinching would be right at the barb from the shank.

A quick test could be to remove the shank and faucet from the tower, reconnect all the tubing, and see if you can serve the beer through it that way (I might even recommend drilling a 7/8" hole in a piece of wood to mount it so that you don't have to hold the shank and faucet).

gnef said:

What is the sharpest bend that the tubing has to make? If it is pinched at any point, it could cause the symptoms that you describe.

Looking at your pictures, the highest likelihood of pinching would be right at the barb from the shank.

A quick test could be to remove the shank and faucet from the tower, reconnect all the tubing, and see if you can serve the beer through it that way (I might even recommend drilling a 7/8" hole in a piece of wood to mount it so that you don't have to hold the shank and faucet).

Click to expand...

gnef, it's actually a fairly gentle bend at the back of the shank. Now that I think about it, though, a suspect spot is the where the line attaches to the D coupler. The top of that barb is about an inch from the bottom of the keezer lid, so, with the line attached, the beer makes an immediate 90 degree turn out of the keg. Maybe I can cut a recess into the lid to ease that

Before you cut anything maybe you can lean the keg over enough to give a decent bend radius (really you only need a couple inch radius for 3/16" ID beer line) and give it a try.

It would sure explain a lot though if you've been literally crimping the beer line nearly closed all this time

Cheers!

day_trippr said:

Before you cut anything maybe you can lean the keg over enough to give a decent bend radius (really you only need a couple inch radius for 3/16" ID beer line) and give it a try.

It would sure explain a lot though if you've been literally crimping the beer line nearly closed all this time

Cheers!

Click to expand...

Ugh, * face palm * I'll give it a shot!

If that turns out to be the problem, you may need to get one of the low profile d couplers with the horizontal connections.

gnef said:

If that turns out to be the problem, you may need to get one of the low profile d couplers with the horizontal connections.

Click to expand...

Didn't know they existed, thanks for the tip!

Here is the first that I remembered from micromatic: http://www.micromatic.com/draft-keg-beer/keg-taps-couplers-pid-FT44T-PR.html

There may be cheaper ones out there though.

edit - just found some other sources for lower cost:

http://www.amazon.com/dp/B006IW80HY/?tag=skimlinks_replacement-20

http://www.beveragefactory.com/draf...an/low_profile_d_system_keg_tap_coupler.shtml

gnef said:

Here is the first that I remembered from micromatic: http://www.micromatic.com/draft-keg-beer/keg-taps-couplers-pid-FT44T-PR.html

There may be cheaper ones out there though.

edit - just found some other sources for lower cost:

http://www.amazon.com/dp/B006IW80HY/?tag=skimlinks_replacement-20

http://www.beveragefactory.com/draf...an/low_profile_d_system_keg_tap_coupler.shtml

Click to expand...

That Amazon one is on the way, hopefully that's the missing link here! Seems well reviewed, will report back. Thanks for the tip!

I was thinking that you could do a quick check by temporarily taking the keg out of the kegerator, making sure that there is no kink, and see if you can pour a pint.

I was trying to get him to just lean the keg over enough...

MagicMatt said:

For the record, I'm not trying to argue either. I just want to help prevent the spread of misinformation regarding these flawed ideas of how resistance and line balancing work. I hear too many people saying things like "too long of lines will cause problems/foaming/etc", which couldn't be further from the truth. Sure, eventually you'll reach a length where the pour is unbearably slow. But changing your lines from 5' to 10' for any reasonable serving pressure >10psi will have minimal effect on flow rate.

I'm not trying to be an expert here, just explain things as much as I comprehend them. Perhaps someone more knowledgeable in this area can contribute better examples. I have a degree in mathematics, but fluid mechanics delves more into the realm of physics, of which it's been a while for me.

Click to expand...

your on the money, extending your lines will not harm the problem of foaming. just as you stated before many jockey boxes are running huge coil lengths... to be honest i think its better to just put 20ft hoses on your kegs and call it a day.

Quick update, I switched faucets and replaced my D coupler tap with a low profile version. Same issue.

HOWEVER, as soon as this keg was done I hooked up a corny keg in its place (my first homebrew, Plinian Legacy, woo!) and it's pouring like a CHAMP. Smooth and consistent every time.

Must've been a "bad" or way overcarbed keg. Thanks for all the help, guys!

~Jer