Recirculation issues that aren't pump related

[wizardofza]

I have a Brutus single tier setup and yesterday was my second attempt at a 10 gallon batch. I've done about 15 or so 5-gallon batches on this setup w/o this issue.

The issue is, when recirculating while I'm mashing the flow is frustratingly slow. It's so slow, that when my mash falls below temp it's tough to NOT overheat it when the burner comes on. I'm connected to a March pump and I pretty much eliminated that as the cause by just disconnecting it. The flow out of the MLT (w/o the pump connected) was realllllyyy slow. I was thinking stuck mash and I kept blowing back into the valve and stirring the mash but it would remain slow.

I had 33lbs of grain in there at ~ .31gallons/lb of water to grain ratio.

I use a converted keg with the ABT false bottom (click here) from NorthernBrewer. But instead, I have 1/2" copper tube connected from the FB to the MLT valve via acompression fitting. All my fittings/valves are 1/2" as well.

I doubt grain is getting under the FB and clogging because it's pretty tight to the bottom, and w/ 33lbs of grain on top of it, I'm sure it's seated well enough - and I just don't see any grain coming out of the MLT valve.

I guess I'm just wondering if anyone has any ideas on what it could be? Or if anyone has some ideas to try?

Should I up my grain/water ratio? Use rice hulls? I'd like to avoid using rice hulls if I can figure out a permanent solution.

I would love to test and figure this out WITHOUT having to do another 10 gallon batch and trouble shoot on the fly again.

It didn't really screw up my brewday, but it made it pretty frustrating to say the least!

Any thoughts would be great!

 

[CodeRage]

I am having a hard time understanding how the plumbing is connected to the FB.

If you have a copper tube running 90 deg down and through the FB, the weight of the grain could be pushing the tube against the keg floor. I found this when I went from 5gal to 10 gal batches. You could cut notches into the bottom of the pickup tube so if it does get pushed against the bottom it doesnt seal up against the keg.

 

[Catt22]

Some possible contributing factors:

1. Are you conditioning the malt with water before milling it? That can make a huge difference. Consider milling the malt a little coaser and sacrificing a few efficiency points for a gain in the flow rate.
2. The FB you linked to is not the best choice as it does not have as much surface area as a full width false bottom such as the one made by Sabco. I have one like yours and it does not perform nearly as well as the full false bottom I have in my Polarware kettle.
3. You said you have 1/2" tubing, hoses and fittings throughout the system. IMO, that's good, but it's best if everything including the fittings are all 1/2" minimum inside diameter particularly on the suction side. Key words being "inside diameter".
4. Increasing the water/grain ratio to 1.5 or 2 quarts/lb should help some.
5. The 33 lbs of grain is a lot and will be a deep grain bed. Grain bed compaction is generally more problematic with a deeper grain bed.
6. When circulating, I've found that it's best to pump only very slightly faster than what you could achieve by gravity flow alone. The pump suction can cause the grain bed to compact and this will slow the flow. I installed a vacuum gauge on my pump so I can see how much suction it's pulling. Without a gauge of some kind, there's no way to know how much suction is being applied. Venting the MT below the FB can help with this and if you use a clear tube, you can use it as a manometer (ie gauge). Randy Mosher mentions this along with some other tips on how to avoid a stuck mash on pages 40-41 in his "Radical Brewing" book.
7. You probably already know this, but don't let the wort level drop below the top of the grain bed. It's best to keep it at least an inch above the grain bed. This keeps the grain in suspension and helps to avoid compaction issues.
8. Install a gate valve and get rid of the ball valve if that is what you are using for flow control on the pump. A gate valve gives you much more precise flow control. Also avoid suddenly opening the valve. This is hard to do with a ball valve as they go from fully closed to fully open in only 1/4 turn and the rate is not at all linear. The gate valve requires 3-1/2 turns to fully open. Much better IMO. I think I may be the only person on the planet using a gate valve instead of a ball valve on my pump.
9. Begin the circulation very slowly at first. Keep it slow for the first 10 minutes or so and only increase the rate very slowly.
10. Dough-in cold (ie Beta Glucan rest @ 95-98 F) for 15 minutes. This will allow the grain to fully hydrate and the enzymes that work at in that temp range will help reduce the gumminess of the mash and get it to flow better.

I've applied all of the above with very good results and without using rice hulls. Post back and let us know if you get it working right.

 

[cwilliams108]

Catt have you tried a globe valve? They provide much better throttling than either gate or ball valves.

 

[CodeRage]

gate/ball/valve really doesnt matter in this case if he has them wide open.

globe valves aren't much better than gate or ball valves. The only reason why a gate valve seems to be more accurate is because there are more turns. The rate of change of the orifice surface area profile are very similar. If you want a high accuracy then you need a needle valve with a V profile. The only down side is they will be more prone to clogging at close to closed positions.

I would bet dollars to donuts that it is a problem with the pick up tube being pushed against the keg floor. Could be a thick mash or compaction of the grain bed too.

 

[Catt22]

Catt have you tried a globe valve? They provide much better throttling than either gate or ball valves.

No, haven't tried a globe valve, but the gate valve works great. I chose the gate valve as the seat is all brass instead of a rubber washer. Either would be a better choice than a ball valve for flow control IMO.

 

[cwilliams108]

On Wiz's topic I agree with Catt and would look specifically at the water to grain ratio.

Gate valves
include wedge and double-disc valves. Both are typically used in a fully open or fully closed position because close regulation of flow is not possible.

A gate valve can be used for throttling only when the valve is in an almost shut position, where most of the flow reduction occurs. The small, crescent-shaped aperture causes a high flow velocity that can erode seat faces. Repeated movement of the disc near the point of closure against upstream pressure can create drag between the seat on the downstream side and may gall or score the seat faces. In addition, the high-velocity flowing liquid impinging against a partially open disc or wedge produces vibration that can damage seating surfaces and score the downstream side.

Nevertheless, a gate valve is excellent for service that requires either full or no flow. It has essentially no flow restriction when fully open. The flow area at the point of control is equal to the full cross-sectional area of the line. Because flow is straight through the line, pressure drop across a gate valve is only about 1/50 that of a globe valve of comparable size. However, globe valves are preferred if lines must be opened and closed frequently.

Globe valves are used for throttling purposes and where positive shutoff is required, in sizes up to 6 in. Globe valves have a replaceable plug and seat, and a metal-to-metal seal. Other globe valves are available with elastomeric disc seals. The easy replacement of the plug and seat makes repair simple and inexpensive.

as read from http://machinedesign.com/BDE/FLUID/bdefp7/bdefp7_5.html

 

[CodeRage]

Yeah, that's all correct. Im not going to argue with you. I've mostly seen globe valves used because of their maintainability. Flow regulation is best left to needle valves where the valve profile changes are linear.

If you're using something like a march pump, the pressure drop across the ball valve will affect the pumps performance in comparison to a gate or ball valve at wide open.

My experience is with large valves for municipal water treatment and distribution. Plus some smaller stuff for treatment. Majority of the time its all about pressure regulation, not flow. When flow is the process variable, the pump is normally what controls flow.

 

[wizardofza]

Instead of the pickup tube that's shown with NT's FB, I replaced it with a 1/2" copper tube connected to an elbow that's connected to my valve via the compression fitting. I wish I had a picture, but my camera is busted.

Anyhow, I never thought of the grain pushing down on the pickup tube where it causes it to be pushed against the bottom. I would almost bet that's what it is.

As far as compaction, I don't think that's it because as this was happening I would stir the mash for fear of compaction and the problem didn't go away.

And yeah, gate valves are definitely the way to go. I just replace all my gas ball valves with gate valves and I love them.

Anyone know where to get stainless 1/2" gate valves? I couldn't find them on mcmaster.

 

[Catt22]

gate/ball/valve really doesnt matter in this case if he has them wide open.

globe valves aren't much better than gate or ball valves. The only reason why a gate valve seems to be more accurate is because there are more turns. The rate of change of the orifice surface area profile are very similar. If you want a high accuracy then you need a needle valve with a V profile. The only down side is they will be more prone to clogging at close to closed positions.

I would bet dollars to donuts that it is a problem with the pick up tube being pushed against the keg floor. Could be a thick mash or compaction of the grain bed too.

I pretty much completely disagree on the valve. If he's running wide open, that could be the problem right there. My pump will suck the grain bed down in a heartbeat running wide open. The rate of change in a gate valve opening is not at all similar to a ball valve, but that's not as much of a problem as the 1/4 turn throw is. I wouldn't even consider trying to use a needle valve for this kind of application. The gate valve provides more than adequate precision. It's a no brainer, ie 3-1/2 turns vs 1/4 turn to fully open. It should be obvious.

The pick up tube being pushed flat against the bottom or not having sufficient clearance below it for whatever reason could certainly cause problems. I have mine rigidly mounted with about 3/8" clearance for just that reason. There may be more than one issue causing the problem. That makes it trickier to figure out.

 

[CodeRage]

Sounds almost exactly like mine. I have the same FB to btw. I think I agree with CAT22 though. Bigger would be better. What I do like about the NB one is you aren't going to collapse that SOB.

I was surprised to when I noticed it. I couldn't understand why after a mash the FB would be hovering off the bottom of the MLT. Then I realized, the pick up tube was pushed down and then when the weight of the grain was gone, the FB gripped the pick up where it lay and sprung up with it.


I don't know if I would use a gate valve for a gas valve. I would be worried about them leaking over time. But, that's just me.

 

[wizardofza]

Just for the record, I wasn't running wide open.

But It actually didn't matter how far open or closed the valve was, I would still get the same result.

I'm tempted to get that Sabco false bottom. It comes with supports.

edit: doh, even though that wouldn't solve my dip tube issue.

 

[CodeRage]

I pretty much completely disagree on the valve. If he's running wide open, that could be the problem right there. My pump will suck the grain bed down in a heartbeat running wide open. The rate of change in a gate valve opening is not at all similar to a ball valve, but that's not as much of a problem as the 1/4 turn throw is. I wouldn't even consider trying to use a needle valve for this kind of application. The gate valve provides more than adequate precision. It's a no brainer, ie 3-1/2 turns vs 1/4 turn to fully open. It should be obvious.

The pick up tube being pushed flat against the bottom or not having sufficient clearance below it for whatever reason could certainly cause problems. I have mine rigidly mounted with about 3/8" clearance for just that reason. There may be more than one issue causing the problem. That makes it trickier to figure out.

I've run mine wide open all the time, had no problems except for a wit that got gummed up.

Wide open and stirring should get you some pretty high flow rates. The fact he still has a problem then points to a different problem.

Whether you can position a valve appropriately within a 45 deg arc or 1260 is a user preference. The change in cross sectional area of the opening changes from fully open to close are very similar, never mine the number of turns. A gear reduction on the stem of the ball valve to match the 3.5 turns over the 45 deg and the valves would work very closely turn for turn.

 

[Catt22]

On Wiz's topic I agree with Catt and would look specifically at the water to grain ratio.

Gate valves
include wedge and double-disc valves. Both are typically used in a fully open or fully closed position because close regulation of flow is not possible.

A gate valve can be used for throttling only when the valve is in an almost shut position, where most of the flow reduction occurs. The small, crescent-shaped aperture causes a high flow velocity that can erode seat faces. Repeated movement of the disc near the point of closure against upstream pressure can create drag between the seat on the downstream side and may gall or score the seat faces. In addition, the high-velocity flowing liquid impinging against a partially open disc or wedge produces vibration that can damage seating surfaces and score the downstream side.

Nevertheless, a gate valve is excellent for service that requires either full or no flow. It has essentially no flow restriction when fully open. The flow area at the point of control is equal to the full cross-sectional area of the line. Because flow is straight through the line, pressure drop across a gate valve is only about 1/50 that of a globe valve of comparable size. However, globe valves are preferred if lines must be opened and closed frequently.

Globe valves are used for throttling purposes and where positive shutoff is required, in sizes up to 6 in. Globe valves have a replaceable plug and seat, and a metal-to-metal seal. Other globe valves are available with elastomeric disc seals. The easy replacement of the plug and seat makes repair simple and inexpensive.

as read from http://machinedesign.com/BDE/FLUID/bdefp7/bdefp7_5.html

While technically correct, pretty much none of that is relevant to our application. This is not a high pressure municipal water line in service full time we are talking about here. The flow rates and pressures are relatively very low. The valve seat is not going to erode significantly in this century or the next, especially considering we only occasionally operate these systems. None of the other things mentioned matter whatsoever in this application. I use a gate valve on the pump for flow and control and also on my elevated HLT to control the sparge water gravity flow. They both do the job very, very well and the change over from ball valves was a vast improvement in flow rate control.

 

[wizardofza]

While technically correct, pretty much none of that is relevant to our application. This is not a high pressure municipal water line in service full time we are talking about here. The flow rates and pressures are relatively very low. The valve seat is not going to erode significantly in this century or the next, especially considering we only occasionally operate these systems. None of the other things mentioned matter whatsoever in this application. I use a gate valve on the pump for flow and control and also on my elevated HLT to control the sparge water gravity flow. They both do the job very, very well and the change over from ball valves was a vast improvement in flow rate control.

Do you use brass or stainless? If stainless, where'd you find them?

 

[Catt22]

Whether you can position a valve appropriately within a 45 deg arc or 1260 is a user preference. The change in cross sectional area of the opening changes from fully open to close are very similar, never mine the number of turns. A gear reduction on the stem of the ball valve to match the 3.5 turns over the 45 deg and the valves would work very closely turn for turn.

A gear reduction in this application for a ball valve? You've got to be kidding, right? The number of turns is what it's all about. With a ball valve it usually goes like this. Bump it open a little. Ooops, too much! Bump it closed a little. Ooops, overshot in the other direction a little. Bump it open a little again and repeat this over and over. I can tweak the gate valve much more easily. It's a huge difference in control. Huge!

 

[Catt22]

Do you use brass or stainless? If stainless, where'd you find them?

I don't have an aversion to brass and I don't have a stainless steel fetish. I'm using off the shelf 1/2" brass gate valves that I bought at Home Depot. Most any hardware or big box store stocks them in the plumbing section. I really don't understand why everyone is not using gate valves on their pumps for flow control. They really work well in this application. You gotta beleive!

 

[Catt22]

I don't know if I would use a gate valve for a gas valve. I would be worried about them leaking over time. But, that's just me.

I don't recall anyone suggesting to use a gate valve as a gas valve. Where did that come from?

 

[CodeRage]

I don't recall anyone suggesting to use a gate valve as a gas valve. Where did that come from?

https://www.homebrewtalk.com/f11/recirculation-issues-arent-pump-related-181381/#post2099536

Yes, you are right about the ability to position the gate valve. With more turns you have a higher resolution, or ease of positioning. The gear reduction was tongue in cheek to illustrate the relationship between position (0-100%) open and closed to surface area are very close to the same between the two. I wouldn't expect any one to do it. I do however have some motorized ball valves that do just that


I'm not saying gate valves are good, bad, right, or wrong; they do give you more resolution. If that is what you need then by all means put em in. To find them in stainless you will probably have to goto flanged connections.

I'd just rather not deal with stem packing and all that good stuff. If you're the clean freak type, it's a nice place for things to hide.

To each his own, it's not personal bud.

 

[Ricand]

I have a Brutus 10 with march pump, but with the full FB. I had to grind the hole a bit bigger on the fb to make sure it didn't mess with the pickup tube. I have an SS ball valve and I can crank the 1.4 qt/lb mash up pretty much from the start and it's full flow. Clears beautifully when the mash is completed. Fly sparging is awesome and I get mid to high 80s routinely.

 

[wizardofza]

I just took a look at my FB setup, and there's no way that my pickup tube is hitting the bottom of the kettle slowing the flow.

The thing is rigid, and with a hose clamp above the FB on the pickup tube itself, there's just no way for it to hit the bottom. I leaned on it as much as I could without breaking it, and it didn't come close to hitting bottom.

So now I'm leaning towards grain/water ratio being the culprit.

 

[CodeRage]

Cool, scratching one thing off at a time is the way to do it.

 

[stevehaun]

3 likely culprits:
1. crush
2. crush
3. crush
I think your crush is probably too fine. Back off the mill gap or try malt conditioning or use rice hulls

 

[Catt22]

https://www.homebrewtalk.com/f11/recirculation-issues-arent-pump-related-181381/#post2099536

Yes, you are right about the ability to position the gate valve. With more turns you have a higher resolution, or ease of positioning. The gear reduction was tongue in cheek to illustrate the relationship between position (0-100%) open and closed to surface area are very close to the same between the two. I wouldn't expect any one to do it. I do however have some motorized ball valves that do just that


I'm not saying gate valves are good, bad, right, or wrong; they do give you more resolution. If that is what you need then by all means put em in. To find them in stainless you will probably have to goto flanged connections.

I'd just rather not deal with stem packing and all that good stuff. If you're the clean freak type, it's a nice place for things to hide.

To each his own, it's not personal bud.

I'm not trying to get into a big argument over valves. Just saying that the gate valves in my experience have proven to be far superior for much improved flow control. It's not a small differenence, it's a huge difference. I have no interest in stainless valves whatsoever, although I would guess they may be hard to come by and they are probably pricey as well. AFAIK, any valve that has a stem will have some sort of packing to make the seal. That's of no real concern to me as this is all pre-boil equipment. Even then, I have fermenters equipped with spigots (basically just another valve) and I've not experienced any contamination problems using those. Again, the surface area of the valve openings isn't the issue. It's how precisely you can make the adjustment that's important. The ball valves suck big time in that regard. The gate valves don't. That's the bottom line for me. By all means do whatever you want to do. I would never try to tell someone how to configure their system and it matters not to me which way they do it. My only point was that it has been my experience that the gate valves work much better. It's not advice, just passing on my experience. Nothing more than that. No, it's not a personal thing with me either. I don't roll that way. Most people are using ball valves throughout their systems. I am simply trying to let people know that there might be a better option. They can then take that and run with it or leave it alone. Most will go with the standard dogma and leave it alone and that's perfectly OK with me.

 

[Bobby_M]

I don't recall anyone suggesting to use a gate valve as a gas valve. Where did that come from?

Totally off topic, but I use gate valves for my nat gas but they're only under pressure while I'm brewing.

 

[wizardofza]

I got my grains from Brewmaster's Warehouse and since it was 33lbs, I figured I'd let them crush it. But when I first took a look at the grain, the first thing I thought was that looked a bit fine.

Some rice hulls would have helped short term had I had any on hand.