Pressure Relief Valve on Plastic Primary?

[ThunderPanda]

I was thinking of better ways to carbonate the other day... And I thought about my small apple juice container that fermented on its own and carbonated itself in its plastic container. I am planning to do this on a larger scale as well, in a one gallon container. The problem is, obviously, that if I don't open the cap often enough, it could explode.

So here is my thought... get a pressure relief valve, find a way to connect it to the lid of a plastic container through drilling a hole and sealing, and then just attach it and start your fermentation. You wouldn't have to worry about it exploding AND you could carbonate in your primary.

The advantages:
-You can taste what your drink is like WITH carbonation before you bottle, so you know what to expect
-No bottle bombs
-You could add sulfite/sorbate while it is still sweet and stabilize your drink. No need to worry about pasteurizing or using fake sweeteners
-Don't even need jugs or carboys!
-Simple

I saw this pressure release valve for a keg, which you may or may not get to work: http://stores.kegconnection.com/Detail.bok?no=239

I just haven't heard a lot about doing something like this without a keg, and I am not totally sure why. I think I should try it

 

[Swib]

I just haven't heard a lot about doing something like this without a keg, and I am not totally sure why. I think I should try it

My first thought is that a chain is only as strong as it's weakest link. So if the pressure relief valve handles more psi than the sidewall of the container, or the seal of the lid, then your container will still burst. Kegs, being steel can handle a great deal of pressure (most are rated around 130psi), but the relief valves are set to release below that level on purpose.

 

[ThunderPanda]

My first thought is that a chain is only as strong as it's weakest link. So if the pressure relief valve handles more psi than the sidewall of the container, or the seal of the lid, then your container will still burst. Kegs, being steel can handle a great deal of pressure (most are rated around 130psi), but the relief valves are set to release below that level on purpose.

I do agree with you, though from experience and research it seems like plastic containers could handle it. Mostly cuz they can expand, but also because they are strong. I remember the mythbusters where they blew up a 2liter... I am fairly certain it got over 200 psi... Pop cans and bottles can all withstand well over 80 but I think typically over 100 psi. So what about an apple juice container not specifically designed for a carbonated beverage? not 100% sure. But the little one I had was far more carbonated than necessary and it had no trouble. I figure I can pressurize to like... 20psi or something pretty easily. And hey if one bursts no big deal..

Nothing ventured nothing gained!

 

[itsme6582]

Why not just put the cap on loose?

 

[ThunderPanda]

Why not just put the cap on loose?

Because then it won't carbonate, plus air could come IN which would be bad. It would have no advantage over an airlock

 

[Swib]

And hey if one bursts no big deal..

Nothing ventured nothing gained!

Agreed, just wanted to make sure you took into account the burst pressure of the container to make sure a relief valve would let go first.

 

[ThunderPanda]

Agreed, just wanted to make sure you took into account the burst pressure of the container to make sure a relief valve would let go first.

Ya I will start out with probably a pretty low pressure for the release valve... Maybe 15-20psi when cooler. That may be all the cider would need anyway

 

[oldmate]

If you keep the juice acidic from the dissolved CO2, it might ferment with some off flavours. For small batches, I usually leave the cap slightly loose to allow CO2 to push out. Once it reaches the ABV I want, I bottle and pasteurise. Too easy.

 

[gregbathurst]

Ya I will start out with probably a pretty low pressure for the release valve... Maybe 15-20psi when cooler. That may be all the cider would need anyway

This sounds interesting. I havent heard of these valves before. How do they attach to a pet bottle, and how easily available are they? I guess if you backsweeten, then put it in the fridge with a valve it would be good for a couple of weeks.

 

[ThunderPanda]

This sounds interesting. I havent heard of these valves before. How do they attach to a pet bottle, and how easily available are they? I guess if you backsweeten, then put it in the fridge with a valve it would be good for a couple of weeks.

They are very easily available, they are used for kegs a lot as well as numerous other uses. I found them for around $5-8. To my knowledge, they don't make them specifically for a PET type bottle, but I think I could probably make a hole in the middle of the cap, slide the valve or a pipe through and seal it up well, and it might work pretty well. I don't know though, I will have to try it and find out!

 

[ThunderPanda]

Why not just put the cap on loose?

In a hilarious twist of fate, that actually works really really well somehow... Thats what I ended up doing. I didn't think it would carbonate at all but it does, a LOT actually, even though it doesn't seem like there is any significant pressure when I press on the side of the plastic jug. It is real bubbly, and this mott's apple juice is tasting delicious.

I did run into a problem though... You can't take a gravity reading while carbonated. I took a sample and am waiting for that sample to go flat, but until then I just gotta wait. But this is seeming like a pretty legitimate way to go I think... Plus I can get motts year round at Target so I am pretty stoked if this turns out well