Author Topic: Calculating weight of BIAB grain bag  (Read 1204 times)

Offline kgs

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Calculating weight of BIAB grain bag
« on: May 03, 2014, 06:04:38 PM »
In the spirit of experimentation I want to brew a BIAB batch just to compare it with MIAT (mash in a tun  :P ). My primary concern going into this is the hassle of dealing with the bag post-mash--that it may be too heavy for me to deal with. Is there a method for calculating the weight of the bag? I will probably target a small batch anyway, but I thought it might be helpful to know going in what I'm dealing with and scale my recipe accordingly.
K.G. Schneider
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Offline euge

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Re: Calculating weight of BIAB grain bag
« Reply #1 on: May 03, 2014, 06:18:39 PM »
If you know your absorption amount per pound of grain you can add that to the premash weight of the grain itself. Ought to be close enough to predict what the bag will weigh.
The first principle is that you must not fool yourself, and you are the easiest person to fool. -Richard P. Feynman

Offline kgs

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Re: Calculating weight of BIAB grain bag
« Reply #2 on: May 03, 2014, 07:07:10 PM »
If you know your absorption amount per pound of grain you can add that to the premash weight of the grain itself. Ought to be close enough to predict what the bag will weigh.

That's what I don't have any idea about. I could go very small as a precaution (2 gallon batch, 1.050, etc.) and then measure and report back...
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Offline Steve in TX

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Re: Calculating weight of BIAB grain bag
« Reply #3 on: May 03, 2014, 09:01:35 PM »
Water absorption is roughly .2-.25 gallons per pound of grain.
Water weighs about 8lbs per gallon.
4 lbs of wet grain will weigh 10.5-12lbs.

These are all ballpark numbers that are close enough for me.

Offline kgs

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Re: Calculating weight of BIAB grain bag
« Reply #4 on: May 04, 2014, 07:56:58 AM »
Water absorption is roughly .2-.25 gallons per pound of grain.
Water weighs about 8lbs per gallon.
4 lbs of wet grain will weigh 10.5-12lbs.

These are all ballpark numbers that are close enough for me.

Thank you. The water absorption is what I didn't have. Though I just thought to check if Beersmith had BIAB equipment profiles and it does, so I could have backed into an answer through the recipe. It's still really good to have this going in.  Triangulation, you know, all in the pursuit of... homebrew!

A 2.5-gallon batch using 5.5 lbs of grain: at .25 gallon absorption, that would add 1.375 gallons, or 11 pounds. That's a 16.5 lb bag. Practicing with a 20-lb bag of sugar or flour ought to give me a sense of how easy it is to hoist a bag out of the kettle.

The Beersmith "mini" BIAB profile is based on a 5-gallon kettle and a 2.91 gallon batch. But that would be almost 4 gallons of water, according to Beersmith. It sounds as if it might be wiser to use my 8-gallon kettle.
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Offline erockrph

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Re: Calculating weight of BIAB grain bag
« Reply #5 on: May 04, 2014, 09:27:21 AM »
I mash 3-gallon BIAB batches in a 5-gallon beverage cooler, and boil in my 5-gallon kettle. Fermcap is required to prevent boilovers, but otherwise it is quite manageable.

Grain absorption is much less than traditional all-grain, especially if you squeeze the bag. I'd start with 0.125 gallon/lb, but (depending on how much/hard you squeeze) it may be significantly lower than that. Absorption is so low, that I don't waste my time calculating out a specific volume for my mash. Almost every batch uses 4 gallons exactly, regardless of the grain bill. I use an extra quart for a 90-minute boil, and 2 extra quarts for a ridiculously hoppy IPA. This is close enough to get me within a couple of points of what I'm shooting for, and I'll generally just tweak the grain bill the next time I brew if I need to.

As far as weight goes, the most I've done is 8lb of grain at a time. This is fairly heavy to lift out of my cooler at first before it is fully drained, but it is manageable enough for my out-of-shape self. I wouldn't want to do a grain bill of more than 10 pounds or so without some kind of pulley system.
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Offline kgs

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Re: Calculating weight of BIAB grain bag
« Reply #6 on: May 04, 2014, 10:49:40 AM »
I mash 3-gallon BIAB batches in a 5-gallon beverage cooler, and boil in my 5-gallon kettle. Fermcap is required to prevent boilovers, but otherwise it is quite manageable.

I can actually do that (I have a 5-gallon cooler I stopped using when I got a 9-gallon Coleman Xtreme) but I'm curious what I'm getting from this procedure that I don't get from my setup and process, aside from upper-arm exercise. I went no-sparge a few batches back and haven't looked back. So BIAB would be the difference between lifting a bag out of a cooler and transferring the cooler's contents into a kettle, versus opening a ball valve and draining into a kettle (I often do push the boundaries and boil 4 gallons in a 5-gal kettle using Fermcap). The bag won't magically transport its contents to the compost bin, so it needs to go somewhere, and that somewhere will need cleaning as well.

In its classic form, where the mash is in the boil kettle, BIAB seems like a low-cost method for getting into all-grain brewing (no need for ball valve, strainer, high-temp hose, cooler, etc.) but I feel like I'm missing something when I read about it.
K.G. Schneider
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Offline denny

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Re: Calculating weight of BIAB grain bag
« Reply #7 on: May 04, 2014, 12:53:52 PM »
I feel like I'm missing something when I read about it.

Maybe, maybe not.  Being pragmatic (OK, lazy), I thought it sounded like a perfect fit for me.  I tried it twice and decided that it was more effort than my usual method.  I don't want to do small batches (in my situation it seems like a waste of time) and dealing with bag that starts with 15 lb. of grain before it even gets wet was too much of a PITA.  Sure, I could have put the bag in a cooler, but what's the point of that if I already mash in a cooler?  Build a lift?  Are you kidding?  I have no doubt that for the right people in the right situations, BIAB is a viable solution.  For me, no way.
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Offline erockrph

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Re: Calculating weight of BIAB grain bag
« Reply #8 on: May 04, 2014, 01:11:19 PM »
I mash 3-gallon BIAB batches in a 5-gallon beverage cooler, and boil in my 5-gallon kettle. Fermcap is required to prevent boilovers, but otherwise it is quite manageable.

I can actually do that (I have a 5-gallon cooler I stopped using when I got a 9-gallon Coleman Xtreme) but I'm curious what I'm getting from this procedure that I don't get from my setup and process, aside from upper-arm exercise. I went no-sparge a few batches back and haven't looked back. So BIAB would be the difference between lifting a bag out of a cooler and transferring the cooler's contents into a kettle, versus opening a ball valve and draining into a kettle (I often do push the boundaries and boil 4 gallons in a 5-gal kettle using Fermcap). The bag won't magically transport its contents to the compost bin, so it needs to go somewhere, and that somewhere will need cleaning as well.

I went the separate cooler mash tun route because I'm lazy and didn't want to deal with monitoring mash temps if I left everything in the kettle. Otherwise, the main advantage of BIAB is that it's a 1-vessel system, so there's no additional equipment beyond the bag.

For me, what I like about the bag vs a manifold/false bottom/bazooka screen is that there's no dead space and less grain absorption. Since I'm only mashing in a 5-gallon cooler, that added efficiency boost lets me brew some bigger beers using my normal setup without having to take extra steps (like adding DME). But frankly, why I really like my system is because I worked it out myself, and because it works well for my purposes (i.e., brewing 3-gallon batches indoors).

Also, if you did want to batch sparge, you could certainly use a bag the same way you'd use a false bottom or screen.

In general, BIAB isn't necessarily a solution to improve all-grain brewing for someone who already has a setup that works for them. But it is an easy way to step up from extract brewing without having to buy a lot of new equipment. It is also quite well suited for brewing smaller batches. If a brewer typically brews 10-15 gallon batches, but wants to brew a 2-gallon pilot batch, then BIAB is a simple option.
Eric B.

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Offline Steve in TX

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Re: Calculating weight of BIAB grain bag
« Reply #9 on: May 04, 2014, 01:29:41 PM »
I have been using BIAB for small stovetop batches. Allows me to make a 12 pack worth of beer while doing other chores (read watch tv). I would not use it for anything larger.

Offline rodmanxxx

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Re: Calculating weight of BIAB grain bag
« Reply #10 on: May 07, 2014, 09:07:12 AM »
The Beersmith "mini" BIAB profile is based on a 5-gallon kettle and a 2.91 gallon batch. But that would be almost 4 gallons of water, according to Beersmith. It sounds as if it might be wiser to use my 8-gallon kettle.

In beersmith I select the 1 step temperature mash for the water calculation. My 8 gallon kettle doesn't hold enough water for traditional 5.5 gallon BIAB batches with ~ 10 lbs grain. The amount of water listed for Saccharification is what I mash with, except I bump it up to 1.5 quarts per pound of grain. Then I use the sparge water amount to rinse the grains in a 5 gallon cooler. After the mash, squeeze the bag, put it in the cooler with the sparge water & let it rinse for 15 minute, stir a bit. At this time I often first wort hop in kettle I pulled the bag out of. After 15 mins, squeeze bag & add wort from cooler to kettle & crank up the burner.
I'm not saying this is how ya should do it, just wanted to give another idea on how i do 5.5 gallon biab batches in an 8 gallon kettle. I do have to cut down the batch size on big beers tho...
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Offline kgs

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Re: Calculating weight of BIAB grain bag
« Reply #11 on: May 20, 2014, 09:44:10 PM »
I have been using BIAB for small stovetop batches. Allows me to make a 12 pack worth of beer while doing other chores (read watch tv). I would not use it for anything larger.

I can see it for that purpose. The grain would likely fit in the same bag I use for my hop spider.
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Offline jimmykx250

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Re: Calculating weight of BIAB grain bag
« Reply #12 on: May 28, 2014, 02:14:59 AM »
I just did a 14 Lb grain bill ipa for  5 gal batch and it wasn't too bad. I will install a lifting eye above the pot next time and hoist it. To do a 5 gal batch i started with 8 gal and ended up with 4.5 finished gallons though.
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