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Pump control - collapsed grain bed

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Hi All,

We have a Jabsco pump from TCW.  In our first mash we collapsed the grain bed by having the pump directly connected to the mash tun.  We are using an all malt mash.  Since that time we have been using a milk can as a grant to prevent pulling a suction and collapsing the grain bed.  This works great.  However, it requires us to manually turn the pump on and off.  We would like to do this automatically.  I believe a high temp float switch will do the job for us.  How is anyone else handling this?  Any better ideas on how to approach this problem?

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Perhaps try sparging soon than you currently are? At the brewery I ran up until last year, our pump pulled directly on the lauter tun, no grant, and did't have a collapsed grain bed in 15 years on all malt brews. Just a simple solution to try before installing a float, keep an inch or so of water on top of the grain bed throughout runoff and you shouldn't have an issue. 

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I don't lauter any more but when I was I used a float switch, very simple and effective.

A slight disadvantage with an on/off switch was it reduced the efficiency of the plate heat exchanger that was in the line, a continuous flow would have been better but no big deal.

If you like gadgets then have the float controlling the pump speed with a variable frequency drive.

 

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Thanks @Brewstilla and @PeteB.  We'll try it again running the pump slower and let the lauter tun be the grant.  If it doesn't work, we're all set up to wire in a float switch to the VFD

Cheers

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6 hours ago, Brewstilla said:

Perhaps try sparging soon than you currently are? At the brewery I ran up until last year, our pump pulled directly on the lauter tun, no grant, and did't have a collapsed grain bed in 15 years on all malt brews. Just a simple solution to try before installing a float, keep an inch or so of water on top of the grain bed throughout runoff and you shouldn't have an issue. 

My guess is that they were using a normal centrifugal pump.  The Jabsco is a PD impeller pump and can pull far more suction.

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4 hours ago, Thatch said:

Thanks @Brewstilla and @PeteB.  We'll try it again running the pump slower and let the lauter tun be the grant.  If it doesn't work, we're all set up to wire in a float switch to the VFD

Cheers

The VFD's I have can be controlled with a 10K pot.(potential divider)  Hook a float onto the pot with stiff wire and with a little tweeking you should be able to keep the level constant.

 

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You have too much pump for what you are doing apparently. Rather than reinventing the wheel, I would change the pump, the impeller size, or put on a VFD. Lauter pumps are generally 1750 not 3450 RPM in my experience depending on total design criteria. There are " Limits " to applying drives to solve equipment mismtach matters. Too many starts per hour is " hard " on any electric motor, especially single phase.

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KISS

Another way which I currently use on my belt press is to insert a T on the outlet from the mash tun. Install an open ended vertical pipe that ends higher than the mash level. It is almost a mini grant. It works well with my small centrifugal pump. If the pump pulls more liquid than is filtering through the screen then air enters through the T and the pump loses its prime for a short time until liquid builds up and re-primes the pump. It is a very basic setup but I have had it running for about 5 years.

Please note that some pumps may not self prime in this situation, and maybe some pumps seals may not appreciate the loss of prime even for a short time.

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5 hours ago, PeteB said:

insert a T on the outlet from the mash tun. Install an open ended vertical pipe that ends higher than the mash level

This is great advice. if you make the pipe transparent, you can also monitor the the level of liquid in it. If it drops well below the liquid level of of your mash tun you know you're pulling liquid out faster than your sparging water is filtering though your grain bed, and risking a stuck mash. This probably isn't possible, but if you are able to raise your mash tun higher than your boiler, you can just use gravity and a valve to control the flow rate, instead of a VFD. That's how many brewhouses are set up, with the mash tun on top of a hot liquor tank or something. 

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Have you tried putting a valve after the pump so you can adjust the flow rate?

With a valve you should be able to match the flow to the sparge water.  Ideally keeping a 1 inch layer of fluid on top the grain bed.

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Thanks for all the help guys, some really great suggestions.  I did mention earlier that the pump is equipped with a VFD.  If none of the suggestions work we'll wire a float switch to the VFD and be done with it.  The pump works great with our milk can grant but manually turning the pump on and off is what we're tying to avoid.  It seems possible that we might be able to solve this with a slower speed and more sparge water.   The KISS principal from @PeteB and @adamOVD  sounds like a winner as well.

Thanks again.

Cheers!

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4 hours ago, DrDistillation said:

Have you tried putting a valve after the pump so you can adjust the flow rate?

With a valve you should be able to match the flow to the sparge water.  Ideally keeping a 1 inch layer of fluid on top the grain bed.

A simple control valve/tap can become blocked if there are any grain particles in the wort.

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@Brewstilla @PeteB @adamOVD   After thinking about this overnight I realize that I left off a key piece of information.  The pump is ten feet higher than the lauter tun.  Our fermenters are on a mezzanine.  I guess I'm back to my original float switch idea unless someone has a better idea.  I think I have to use the grant (milk can) to keep from pulling a vacuum and collapsing the grain bed.  Any thoughts?

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I imagined the pump would be below the lauter screen. With it 10 feet above then my suggestion of a T and stand pipe would not work with a regular centrifugal pump. You would need a pump that easily self primed and didn't mind being run dry for short periods. Generally, pumps have less problems if mounted below the delivery liquid and with a short suction hose. 

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Can you move the pump down to the level of your lauter tun and then run a hose to your fermenter? Then when you are finished running off push the last of the wash through the pump/hose with water or CO2.

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19 hours ago, PeteB said:

A simple control valve/tap can become blocked if there are any grain particles in the wort.

Never seen this happen.  First you shouldn't be seeing grain going through a lauter or you're doing it wrong.  It would take a lot of grain to plug up a 2" connection or bigger.  I've never even had a blockage at home with a 1/2 system doing lautering for brewing or other ventures.

Ideally you have a ball valve, filter, then adjustable valve inline.  So in the event you get a blockage you can close the previous valve, clean the filter or down line valve and keep going. But this shouldn't really happen if you lauter correctly.

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2 hours ago, adamOVD said:

Can you move the pump down to the level of your lauter tun and then run a hose to your fermenter? Then when you are finished running off push the last of the wash through the pump/hose with water or CO2.

No room on the floor but plenty of room on the mezzanine.  I'm probably going to have to go with the float switch.

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4 hours ago, DrDistillation said:

Never seen this happen.  First you shouldn't be seeing grain going through a lauter or you're doing it wrong.  It would take a lot of grain to plug up a 2" connection or bigger.  I've never even had a blockage at home with a 1/2 system doing lautering for brewing or other ventures.

Ideally you have a ball valve, filter, then adjustable valve inline.  So in the event you get a blockage you can close the previous valve, clean the filter or down line valve and keep going. But this shouldn't really happen if you lauter correctly.

Many of you on this forum will be fermenting and distilling with grains in so you may not understand lautering.

Briefly the mash is on top of a perforated screen than is held just off the bottom of the mash vessel. At the start of runoff some small particles get through the screen so to get a clear wort the first runoff is recirculated to the top of the grain bed. After a time the grain bed itself becomes a depth filter and traps even very small particles.

But there will always be some solids from the start of the runoff that are still in the gap under the screen that could dislodge and block a control valve in certain situations. For example if the pump produces a high pressure when the outlet is restricted then the control valve will needed to be almost shut if you need a small flow and it could get blocked. (I had this situation quite often in a different industry)  With a low pressure pump and a large flow then the valve will have a reasonable valve opening and blockage is very unlikely.

I didn't realise until I visited several Scottish distilleries last year that they didn't recirculate to get a clear wort, they even had mechanical rakes to stir up the grain bed between sparges (additions of extra water to wash sugars out) that would wash more grain through the lauter screen. They would have been fermenting with a small amount of grain in.

DrDistillation said   "But this shouldn't really happen if you lauter correctly. " That could be correct if you are making a modern beer but for distillation there is no "correct" way.

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I think you're overthinking things.  Unless you're using a small pipe or running a valve mostly closed (wrong pump if so) getting a blockage just doesn't happen IMHO.  That's from using a 30 BBLTilting Lauter Tun Tank  with rakes.  Small particles even cracked corn never cause a block on a 2" or larger pipe. 

Agree with you on distillers wort vs brewers wort.  You don't need and may not want clear wort. Dirty wort for flavor but not dirty enough to scorch if using direct heat.

I'd suggest installing the double valve method I mentioned and trying it with the knowledge if it doesn't work you can easily switch over to your tank method mid lauter if needed.  Nothing to loose by trying it but everything to gain.  But that's just my humble opinion.

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We had a hell of a time today getting our mash pumped over and I came here looking for ideas...and I see someone nearby in Brunswick is having some issues with pumps too...I have a feeling I know which distillery! Hi! Thanks for the malt for sanitizer!

On 6/1/2020 at 3:34 PM, Thatch said:

Hi All,

We have a Jabsco pump from TCW.  In our first mash we collapsed the grain bed by having the pump directly connected to the mash tun.  We are using an all malt mash.  Since that time we have been using a milk can as a grant to prevent pulling a suction and collapsing the grain bed.  This works great.  However, it requires us to manually turn the pump on and off.  We would like to do this automatically.  I believe a high temp float switch will do the job for us.  How is anyone else handling this?  Any better ideas on how to approach this problem?

 

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1 hour ago, bconley said:

Hi! Thanks for the malt for sanitizer!

You're welcome.  We are adding a float valve to our grant since we have to pump uphill.

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