Sparging with balancing valves?

[patterns]

I'm building up a single tier system with a HLT, mash tun, kettle and 2 pumps. I'm considering using pressure independent balancing valves (aka griswold valve) on the outlet of each pump in order to help maintain my sparge flow rates into and out of the mash tun.

When fly sparging it is important to keep an inch or so of fluid on top of the grain bed so as to not compress the grain. In order to do this most people (I believe) either modulate the pump from the HLT to mash tun on and off (which can't be great for the motor), or leave both pumps running and partially close a ball valve on each pumps outlet (but this still requires a bit of watching since you will never get both valves dialed in exactly the same.

If I threw a pressure independent balancing valve on the outlet it would give me even flow in and out every time without any fiddling required by me.

So why haven't I seen anyone else ever talk about this? Is it the first cost (I'm not worried about that, I have a hookup). Or maybe the likely-hood of the valve getting clogged up (I could throw a little strainer in front of it, but that's just extra pressure drop for the pump now)

Anyone have any input about this?

[Ozwald]

I don't know a lot about those valves, but I don't see how they would balance the flow rate of 2 different vessels to each other. I have a basic understanding of how they work & what they're intended to do, but that's not going to help fly sparging. Your second assumption was correct (leaving both pumps running & adjusting the output with a valve). It takes some practice, but you can get them balanced fairly easily. If you're looking for a more hands-off approach, a float valve does the trick nicely - look at Blichmann's AutoSparge system for a good example - there's other types/styles of float valves & I'm pretty sure you could build a much better one than the Blichmann, but I'm just referencing the idea & how a float valve works.

[patterns]

The valves are able to be set to a flow rate and they automatically open or close in response to a change in pressure. Basically you set the flow rate you want and the valve does the work to give it to you.

The float valve just controls the pump on and off which isn't great for the motor.

[Ozwald]

The valves are able to be set to a flow rate and they automatically open or close in response to a change in pressure. Basically you set the flow rate you want and the valve does the work to give it to you.

The float valve just controls the pump on and off which isn't great for the motor.

I understand how they work, but they're going to give you a constant output based on a variable input, which really isn't the case with fly sparging. Also that constant output needs to be variable, which is another thing those aren't going to help you with. Secondly, the float valve does not cycle the motor at all. The motor stays on all the time. It controls the flow. It's just like having a ball valve that you don't need to touch; it'll automatically match the output of the 2nd vessel... the exact thing you're trying to accomplish.

[patterns]

I was thinking you were talking about a float switch that would activate a relay turning the pump on and off. I looked up and Blichman autosparge and see what you mean now. I had seen that before and just forgot.

Also that constant output needs to be variable

I guess this is what I am having trouble wrapping my mind around. I've always batch sparged and am setting up my new system to fly sparge. So why would the sparge flow rates in and out of the mash tun need to be variable?

And thanks Ozwald. I appreciate the help.

[Ozwald]

So why would the sparge flow rates in and out of the mash tun need to be variable?

Try it a couple times & you'll find out in a hurry

It's going to vary from system to system & recipe to recipe. Another of my famous frozen pizza analogies: Bake two brands in two different ovens at sea level & again in two different ovens at 6000'. You'll have 8 different temp/time combos to achieve the same result (2x2x2). One system (oven) is going to require a certain rate (time/temp) for a certain recipe (brand). There's also going to be other variables that aren't going to be so black & white. I call them 'Oh, fuck' moments.

It's really not as hard as it sounds. The first couple batches can be a bitch to get things to settle in, but with a little practice it'll come pretty naturally. It's easier to learn while you fuck up the first couple than it is to read it.

[CRBrewHound]

Just to throw my hat in the ring, this is not something that has to be perfect. For successful fly sparging you do not have to maintain an exact level of fluid on top of the grain bed (for example 1"). Two ball valves will work just fine. if you water level above the grain bed starts getting to low, open the input valve a little or close the output valve a little. If it starts to get to high. Close the input valve a little or open the output valve a little.

I understanding trying to built the perfect system, where you just sit there and get drunk while it does everything. But somethings are far more trouble and complicated then they are worth.

[Ozwald]

I understanding trying to built the perfect system, where you just sit there and get drunk while it does everything.

That's called the liquor/beer store

Following your side topic, I never saw the point in building a fully automated homebrewery... aren't we doing this cause we want to brew? I've got a pretty advanced brewery, but I still like cranking valves, stirring my mash, etc. If I was going to automate anything, it'd stuff in the clean up stage. Just my thoughts on that.