How do I know when the keg is full?

[tomakana]

OK - this may be a really simplistic question - when you're filling the keg, how do you know when it's "full"? I'm getting ready to keg a batch for the first time using a 2.5 gallon corny keg. I know I have a little over 3 gallons in my fermenter, so I'll have a couple of bottles to fill at the end. Since there are no volume markings on the keg, and it's obviously not see-through, not positive how I know when I'm not underfilling or overfilling.

Is it as simple as filling it with 2.5 gallons of water (still need to clean and sanitize it anyway) to see how high that comes, then eyeballing it while keeping an eye on the amount in the fermenter when I transfer the beer? I know it's not a huge deal if it's a little over or under the 2.5 gallons, but I don't want to inadvertently leave too little headspace (or for that matter have to bottle more than I have to)

Thanks!

 

[Konadog]

If the beer your transferring is cold, you could just watch the condensate line on the keg move up until full, just transfer slow.

 

[ba-brewer]

You want to make sure the fill level is below gas in tube to prevent sending beer up your gas line. Some people stop filling at the transition from to straight to domed.

If you do an open transfer it easy to tell how full, get trickier if you do a closed transfer. First time just do an open transfer then start looking into closed transfers.

 

[bleme]

You could fill it with water (or Star San) to the level you want and weigh it.

 

[Rackrunner]

I use a small piece of 2x4 to prop up the side of the keg below the liquid post, so it's tilted ~20-30 degrees towards the gas post. Then I attach a gas connector+ small piece of hose to the gas post (run it into small jar or bucket) rather than using the pressure relief valve.

I then fill the keg until I start to see a sputter or two of beer coming out the gas hose and turn off the flow. Once you remove the 2x4 prop you should have a nice full keg, up to about 1/2" below the gas tube.

 

[bracconiere]

i never knew i could have kegs too full! learn something new every day around these parts!


(the only time i had a keg TOO full, i was just upset i had to mop the floor)

 

[dwightr8]

This is a good question. I recently started doing pressure fermentation and thus pressure transfers and had never really thought about it. I think I'll rig up a picnic tap connected to the gas post and use that to relieve the pressure during transfer. When I start getting beer out I'll stop and drain it down a bit till no more beer and I should be good to go.

 

[ba-brewer]

i never knew i could have kegs too full! learn something new every day around these parts!


(the only time i had a keg TOO full, i was just upset i had to mop the floor)

Not really a true bad thing but how full you fill your kegs will effect how long it takes to carbonate as the speed is relative to surface area. The higher up into the dome the longer it will take.

 

[McKnuckle]

I solve this problem by always brewing a little less than the keg's capacity, which is probably the opposite of most brewers' instincts. But it does work!

 

[Golddiggie]

I use a small piece of 2x4 to prop up the side of the keg below the liquid post, so it's tilted ~20-30 degrees towards the gas post. Then I attach a gas connector+ small piece of hose to the gas post (run it into small jar or bucket) rather than using the pressure relief valve.

I then fill the keg until I start to see a sputter or two of beer coming out the gas hose and turn off the flow. Once you remove the 2x4 prop you should have a nice full keg, up to about 1/2" below the gas tube.

I might have to use some of that method for my coming transfers (this weekend). One of them is a 9 gallon batch going into a 6 gallon and 3 gallon keg. I have some spare gas QDs that I could setup for the 'overflow' indicator with some tubing and such. I happen to have a spare 2x4 hanging around (was using it to hold the fermentation chamber lid up before I installed the gas springs).

I solve this problem by always brewing a little less than the keg's capacity, which is probably the opposite of most brewers' instincts. But it does work!

I put enough into the fermenter that I'll get my target volume out (3 gallon increments). I also have the fermenter extraction dip tubes cut to leave a set volume behind. That's the typical amount of space taken up by the yeast cake and trub when it's all done. Knowing I'll leave X quarts behind, I can brew so that my volume into fermenter is just a bit more. Never a bad thing to have a keg full of clear (or proper) brew. I would hate to be off and not have enough to fill the keg(s).

 

[dwightr8]

I solve this problem by always brewing a little less than the keg's capacity, which is probably the opposite of most brewers' instincts. But it does work!

I try to do this too, but I'm fermenting ~3 gal in a 5 gal keg and then transferring to a 3 gal keg.

 

[bracconiere]

Not really a true bad thing but how full you fill your kegs will effect how long it takes to carbonate as the speed is relative to surface area. The higher up into the dome the longer it will take.

not for me, i just carbed two kegs one was almost overflowing, and the other one was about4-5"'s down from the top....but both got 1.2oz's of co2!

now that i think about it, should be interesting how much the head space affects the carb level in the beer. i'd imagine the head space would be included in the vol calculator? 1.23oz a 5 gallon volume. and another thingy tells me because it was fermented it allready has a bit more then .8 vols?

 

[Qhrumphf]

Can fill to weight. If we assume your beer is cold crashed and 38-40F, your beer should weight it's final gravity in kg/L (if your beer finished at 1.015 that's 1.015 kg/l), or 8.345 * its final gravity in pounds per gallon. If you're not crashed and at room temp. At room temp it'll be less dense, so use 8.33*FG for lbs/gal or 0.997*FG for kg/l. Tare off your scale with the empty keg and then fill to that weight.

To be exact you'd need to use the exact temp and the actual weight of water at that temp (and then multiply that by your FG to get your fill weight). Either way it'll get you very close.

 

[cubalz]

My suggestion going forward is to create your recipe using enough strike water to allow for boil off, trub and fermenter losses to end up with 2.5 gals in the keg. That way you never have to worry about it again. For this batch, follow Bleme's instructions on pre weighing with water.

 

[Holden Caulfield]

Weigh it with a postal scale. Just calculate the weight of the beer you are packaging (8.34*FG*Gallons), tare the scale, and fill it up through the out dip tube.

This is what I do to pressure transfer my beer, minimize oxygen exposure, and eliminate any chance of nasties getting in.

 

[eric19312]

Another vote for the postage scale. My ball lock kegs with my spunding valve weigh a few ounces less than 10 pounds empty. I fill them to 51 pounds total weight. I do it this way instead of tareing the empty keg just in case my scale turns off mid fill. A bit more than 41 pints per keg. They will hold a little more than that but I prefer to stop when I know it is full to 51 pounds rather than dribble beer through the spunding valve onto the floor.

 

[bracconiere]

i'd have to say now that digital scales are cheap. weight is the 'weigh". for cooking, brewing, and a lot of other stuff. it's just the best way!


never really thought about putting a keg on a scale though. i open air transfer, and just keep my eye on it till it's about at the lid.

edit: there's even some that stay on 24/7 if plugged in, mines been for a year now. except for that brown out. (and being that when i swapped my tank, it's only driffted -0.6oz's in that time.

 

[LittleRiver]

Another vote for doing it by weight. I use the same postal scale I use to weigh grain.

In addition to my 5gal kegs I have a couple of 3gal. For them I brew a six gallon batch and split between them. To one of the kegs I add a dry hop or fruit.

 

[jerrylotto]

I agree about weighing your empty kegs and marking a tare on them. You can get a pretty good estimate of the fill level if you measure the weight of the liquid.

 

[eric19312]

i'd have to say now that digital scales are cheap. weight is the 'weigh". for cooking, brewing, and a lot of other stuff. it's just the best way!


never really thought about putting a keg on a scale though. i open air transfer, and just keep my eye on it till it's about at the lid.

edit: there's even some that stay on 24/7 if plugged in, mines been for a year now. except for that brown out. (and being that when i swapped my tank, it's only driffted -0.6oz's in that time.

Mine would stay on 24/7 if I could only find the right AC adapter that I misplaced.

 

[norrismj]

As I fill I watch the condensation on the outside of the keg and stop when it hits the upper rubber. Make sure you let it rest as the condensation is a little slower. There is a lag time.

 

[day_trippr]

fwiw, I note the keg tare weight, add the weight of 5 gallons of beer at whatever FG (math already shown above) then let the transfer rip until the fermenter is empty or the calculated gross keg weight is reached. I have a gas-side keg blow-off submerged in a half-filled bucket of water in case I somehow screw up the math

Cheers!

 

[jddevinn]

I just fill until the beer starts coming out of the CO2 in port that is venting through sanitizer. There are also check valves that stop flow once you reach this point.
https://kegfactory.com/products/duo...MInp-84s-S7QIVEGyGCh2n3Q3dEAQYAiABEgIUXfD_BwE

 

[Ogilthorpe2]

fwiw, I note the keg tare weight, add the weight of 5 gallons of beer at whatever FG (math already shown above) then let the transfer rip until the fermenter is empty or the calculated gross keg weight is reached. I have a gas-side keg blow-off submerged in a half-filled bucket of water in case I somehow screw up the math


View attachment 707263

Cheers!

I do the same, except my blow off, blows back into the fermenter. That way the beer leaving the fermenter is replaced by CO2 being forced from the previously purged keg by the incoming beer. Closed loop Gravity Transfer.

 

[Vale71]

I do closed transfers with a spunding valve attached to the gas post of the keg to release pressure at a constant rate.
I thought about going the scale route to determine when a keg is full but I preferred to keep it simpler. When I hear the spunding valve start spluttering beer I just remove it and then quickly detach the beer line as well. This means that the gas post is picking up beer but I solve this simply by serving the first pint from a new keg without attaching the gas line. The pressure in the headspace is more than enough (this is fully carbed, spunded beer) to push a pint of the beer out and after the first pint the beer level has definitely dropped way lower than the gas tube so that the gas line can be safely attached without risking backflow.

 

[stiray]

I use a small piece of 2x4 to prop up the side of the keg below the liquid post, so it's tilted ~20-30 degrees towards the gas post. Then I attach a gas connector+ small piece of hose to the gas post (run it into small jar or bucket) rather than using the pressure relief valve.

I then fill the keg until I start to see a sputter or two of beer coming out the gas hose and turn off the flow. Once you remove the 2x4 prop you should have a nice full keg, up to about 1/2" below the gas tube.

Great idea! Best solutions are always simple Running to mitre saw...

 

[sibelman]

This is simple and brilliant. Only down side: beer gets in the gas post, which then requires cleaning once the keg is emptied.

I often skip cleaning the gas post & its poppet when cleaning kegs because, usually, they stay clean.

Alternatively, a scale can show the weight of the keg growing during transfer as indicated above.

Cheers!

 

[stiray]

This is simple and brilliant. Only down side: beer gets in the gas post, which then requires cleaning once the keg is emptied.

I often skip cleaning the gas post & its poppet when cleaning kegs because, usually, they stay clean.

Alternatively, a scale can show the weight of the keg growing during transfer as indicated above.

Cheers!

Today I cleaned 3 old kegs full of beer stone (second hand buy, but they were dirty cheap - 90 euros for all 3) and currently cleaning the gas post seem unimportantly small task Finally have everything in place so I can try my first kegging (in closed loop so I imagine the flow will stop when gas post gets closed by beer).

 

[sibelman]

the flow will stop when gas post gets closed by beer

Maybe not. My intuition says the flow will continue until the levels equalize. Gravity!

Congrats on reconditioning those kegs. I imagine you've pressure tested them and replaced o-rings.

I wish you the best of luck with your move into the world of kegging!

 

[redrocker652002]

The weight idea sound like a good one. I must have been lucky, as I just set my fermenting bucket on the dryer, keg on the floor, open the PRV, valve on the bucket and let it go. Have not had any spillage yet, but I think I am in the 4.5 gallon range on most after trub and yeast settlement on the bottom of the bucket. I have not opened the lid on the keg to see where I am at in risk of O2 exposure. But now you all have me curious as to how much I am filling the keg.

 

[sibelman]

curious as to how much I am filling the keg

The main thing is to avoid over-filling. I've usually fallen a bit short of my target fermenter volume, so for me this only became an issue as my "aim" got better.

When surprised by beer starting to flow out the gas in side (because I was too lazy to use the scale) , I can push the "surplus" out with CO2, and then carb.

Of course, surplus is a misnomer. To paraphrase comedian Margaret Cho, "Dahling, there is no such thing as surplus beer." (She wasn't talking about beer, of course.)

 

[Yesfan]

I fill by weight. I have a piece of tape on my kegs with the empty weight and full weight amounts. When I do a transfer, I just watch the scale and when I get close, shut her off. I have the 9.5mm EVA Barrier line for my transfers. I put a Duotight shut off valve on one end, so I can close off the flow when transferring to a second keg.

 

[day_trippr]

I also use a digital scale when filling kegs because I'm wicked OC about getting a full five gallons in each of two kegs for every batch I brew to maximize the payback for the effort - and get cranky if I'm short a quart. But I'm a creature of habit so I've tuned every recipe to assure some drama on kegging day - they almost always end up within a few ounces of 5 gallons now.

Also, there is a "Keg Volume Calculator" spreadsheet that an HBT forum member created that helps calculate expected weight for a full fill based on FG, carbonation, altitude and temperature with the keg tare weight, so you can stop the racking before over-filling a keg. Very helpful, I use it all the time...

Cheers!

 

[sibelman]

Nice photo, @day_trippr . Is the shirt decorative or to mitigate photo-skunking? Or is that a glass carboy?

 

[day_trippr]

It's primarily for anti-skunking. It is a glass carboy, and the shirt is also commemorative as it was my dad's brother's company that had the "Cable Busters" shirts done a long time ago...

Cheers!

 

[JohnDBrewer]

I use weight, too. Just did 42lbs of kolsch, which worked out to be 4.97gal at a SG of 1.013. Beesmith has a "weight to volume" calculator under the "tools" section.

 

[TLaffey]

I use a small piece of 2x4 to prop up the side of the keg below the liquid post, so it's tilted ~20-30 degrees towards the gas post. Then I attach a gas connector+ small piece of hose to the gas post (run it into small jar or bucket) rather than using the pressure relief valve.

I then fill the keg until I start to see a sputter or two of beer coming out the gas hose and turn off the flow. Once you remove the 2x4 prop you should have a nice full keg, up to about 1/2" below the gas tube.

Add a spunding valve if your beer is already carbonated. With a fermenter at 15psi, holding the keg around 10psi allows it to fill without too much loss of CO2. I started "tipping" the destination keg before I had a scale and it's so simple I've stuck with it.