What's the ideal RIMS pump flow?

[the_dragonlord]

Hello everybody, I'm Andrea from Italy and I've just setted up my RIMS little plant (I brew 23lts batches). At now I use a solar project plastic pump with a flow of 11lts/min but when I put the crushed grain in the water the flow decreases too much (I'm afraid), so I think I need a more powerful pump. Unfortunately here in Italy plastic-magnetic-food grade pumps costs a lot of money so before buying a new one I want to be sure at 300%!
What is about the "ideal" flow in terms of lts/min for a RIMS system?
I'm afraid that if the flow is too low the wort could "burn" flowing "around" the heater (I have a 1500W heater made in AISI316L Steel with a density of about 6,8W/square cm) and, on the other hand, if the flow is too high the sugar extraction from the crushed grains could not be done perfectly.

Can someone help me?

Thanks, regards and have a beer day!
Andrea

 

[USAFSooner]

Most of the magnetic pumps used here for brewing run at 22 liters/min max flow.

 

[LordUlrich]

The problem here is that it is far more complicated than it appears. While pumps are rated in l/min it is really a useless number for this purpose as it is the max flow rate with no restriction, the pump curve is really what matters. A pump curve will show you flow vs restriction (in head). Pump curves are unique to each model of pump.

As far as scorching, as long as you have flow I have yet to see a confirmed case of scorching which has impacted the flavor of the beer. I would worry far more about too much flow causing a compacted grain bed. I typically aim for a 1-2 quart/min (pretty close to 1-2 l/min). It happens to be close to the recommended fly sparging speed. I am running with the ball valve on the outlet of my pump mostly closed.

Hope it helps.

 

[the_dragonlord]

The problem here is that it is far more complicated than it appears. While pumps are rated in l/min it is really a useless number for this purpose as it is the max flow rate with no restriction, the pump curve is really what matters. A pump curve will show you flow vs restriction (in head). Pump curves are unique to each model of pump.

As far as scorching, as long as you have flow I have yet to see a confirmed case of scorching which has impacted the flavor of the beer. I would worry far more about too much flow causing a compacted grain bed. I typically aim for a 1-2 quart/min (pretty close to 1-2 l/min). It happens to be close to the recommended fly sparging speed. I am running with the ball valve on the outlet of my pump mostly closed.

Hope it helps.

It helped a lot!
Thanks!
Have a beer day
Andrea

 

[Shockerengr]

I run my rims tube during the mash with the pump as high as it can go without causing a stuck mash (in my case - generally wide open) This gets the most flow past the element and helps the rims performance.

When I go to sparge, I throttle the pump way back to get better sugar extraction. My sparge flow rates are around a 1/4 of my mash flow rates

 

[the_dragonlord]

I run my rims tube during the mash with the pump as high as it can go without causing a stuck mash (in my case - generally wide open) This gets the most flow past the element and helps the rims performance.

When I go to sparge, I throttle the pump way back to get better sugar extraction. My sparge flow rates are around a 1/4 of my mash flow rates

Thanks! What model of pump do you use? Magnetic? Made of food-grade plastic?
Thanks
Andrea

 

[Shockerengr]

I use a march 809-HS pump - Polysulfone head (food grade plastic good for boiling) and magnetic. It's pretty common for brewers in the US.

I do run a 30 gallon (110L) mash tun, so I have a lot of surface area on the bottom that lets me run high flows with less chance of getting a stuck mash.

 

[the_dragonlord]

I use a march 809-HS pump - Polysulfone head (food grade plastic good for boiling) and magnetic. It's pretty common for brewers in the US.

I do run a 30 gallon (110L) mash tun, so I have a lot of surface area on the bottom that lets me run high flows with less chance of getting a stuck mash.

Wow! Unfortunately this model of pump isn't sold here in Europe...the only online shops are there in the US....thanks!
Andrea

 

[audger]

sugar extraction (more specifically- "conversion") is accomplished at zero flow rate in non-recirculated systems. flow rate of a pump does not relate to the amount of extracted / converted sugars.

what recirculating does is; maintain the entire mash at a more consistent and more accurate temperature; makes the runoff clearer by filtering thru the grainbed, among a few other things.

there is no such thing as a flow rate being too high. as long as your false bottom can prevent your mash from compacting and becoming stuck, you can circulate at 50L/min if you wanted. however if your flow rate is too low, your temperature throughout the mash might not be uniform. in other words, you want the flow to be as fast as possible without the grain becoming compacted.

 

[Shockerengr]

sugar extraction (more specifically- "conversion") is accomplished at zero flow rate in non-recirculated systems. flow rate of a pump does not relate to the amount of extracted / converted sugars.

what recirculating does is; maintain the entire mash at a more consistent and more accurate temperature; makes the runoff clearer by filtering thru the grainbed, among a few other things.

there is no such thing as a flow rate being too high. as long as your false bottom can prevent your mash from compacting and becoming stuck, you can circulate at 50L/min if you wanted. however if your flow rate is too low, your temperature throughout the mash might not be uniform. in other words, you want the flow to be as fast as possible without the grain becoming compacted.

Largely true, but channeling can still happen, as well as the diffusion of the sugars through the grain bed can have an effect on efficiency.

But I'll agree that it won't have more than a few percent effect on efficiency as long as you don't have bad channelling issues.

 

[CapnBry]

As a datapoint, the Blichman 15g false bottom is rated for 1gpm ~3.8lpm max. When I ran it at 2.5gpm with 0.039" milling gap I'd sometimes get stuck mashes. I've since throttled it back to 1.5gpm and haven't had a problem. It depends on your milling gap and false bottom, but I've gone as low as 1gpm and gotten pretty consistent temperatures through the grain bed. I use chugger SS pumps.

EDIT: But mine is a HERMS system.