Fermentasaurus cold crashing

[BrewRunning]

I’ll be cold crashing for the first time soon in a fermentasaurus. Since it’s plastic I assume the negative pressure will cave the sides in.

I have the pressure kit on it. Will hooking up CO2 and keeping it under pressure alleviate this? If so, how much pressure needs to be applied?

Thanks!

 

[day_trippr]

All it takes is slightly positive CO2 pressure to keep the vessel from collapsing. All you're doing is backfilling the head space. I use 0.4 psi on my fermentors...

Cheers!

 

[BrewRunning]

Thanks!

 

[cswant88]

The CO2 gauge on my regulator goes to 60psi, so its hard to get and accurate read on lower pressures, I turn mine up until my eyes detect movement on the needle, probably between 1-2 psi.

 

[burtom]

If you pressurize the fermenter to 5 PSI and it holds pressure you can crash to 32 degrees without any issues.

 

[day_trippr]

Again, there's no need for more than the slightest positive pressure to prevent collapse. Certainly no need for 5 psi...

Cheers!

 

[Unicorn_Platypus]

Again, there's no need for more than the slightest positive pressure to prevent collapse. Certainly no need for 5 psi...

Cheers!

I don't have a secondary tank to hook up while cold crashing. Will simply having the fermentor @ 30 PSI in the headspace prior to crashing be enough positive pressure to account for the temperature drop from 70 to 35 degrees F?

 

[day_trippr]

Probably depends on ratio of head space to total volume, but in general I would think that would work.
But it's really a @doug293cz question - right in his wheelhouse, I'd think.
He gets summoned a lot for gas questions

Cheers!

 

[Unicorn_Platypus]

In

Probably depends on ratio of head space to total volume, but in general I would think that would work.
But it's really a @doug293cz question - right in his wheelhouse, I'd think.
He gets summoned a lot for gas questions

Cheers!

There would be a lot of headspace in this case as its an 8g fermentor and I'll have at most 6 gallons in there.

I also plan to set spunding valve @ 30 PSI for about a week or so before crashing to let it naturally carbonate a bit. But this will be my first experience with spunding so definitely a noob

Guess I'm going to have to pressure test the new fermentor anyway. I'll try it with 5g of water and see how much the pressure drops

 

[DVCNick]

On my gauge, mine drops about 2-3 PSI going from ferment temp to ~34F. 30psi is WAAAY more than enough to worry about any negative pressure issues.

 

[BrewChef]

In


There would be a lot of headspace in this case as its an 8g fermentor and I'll have at most 6 gallons in there.

I also plan to set spunding valve @ 30 PSI for about a week or so before crashing to let it naturally carbonate a bit. But this will be my first experience with spunding so definitely a noob

Guess I'm going to have to pressure test the new fermentor anyway. I'll try it with 5g of water and see how much the pressure drops

Hi,
I just did this last week with fermentasaurus. This was my experience,
I fermented at 82 degrees (hot head yeast), 7.1 gallon fermenter, 6 gallons beer inside
fermented under pressure for 2 weeks at 15 psi (spunding valve and pressure kit)
cold crashed to 39 degrees with spunding valve still at 15 psi, in 2 days I lost 8 pounds of pressure (only could do outside, no fridge big enough to hold it yet)
I then re-pressurized to 15 psi for 1 day and it was ready to keg / drink

anyone have any experience with the temp twister for the fermentasaurus? I was thinking to use that for cold crashing instead of a huge fridge

 

[Unicorn_Platypus]

Hi,
I just did this last week with fermentasaurus. This was my experience,
I fermented at 82 degrees (hot head yeast), 7.1 gallon fermenter, 6 gallons beer inside
fermented under pressure for 2 weeks at 15 psi (spunding valve and pressure kit)
cold crashed to 39 degrees with spunding valve still at 15 psi, in 2 days I lost 8 pounds of pressure (only could do outside, no fridge big enough to hold it yet)
I then re-pressurized to 15 psi for 1 day and it was ready to keg / drink

anyone have any experience with the temp twister for the fermentasaurus? I was thinking to use that for cold crashing instead of a huge fridge

Thanks for reporting back! I won't be brewing again until after the quarantine in NYC, but looking forward to testing this out on my next brew day.

Planning to brew a post corona virus mexican lager under pressure called "Schwag Ultra"


I just purchased on of these. It fits in a chest fridge. Hold pressure like a fermentasaurus/fermzila, but doesn't have the conical features. I don't harvest yeast, so it suits my needs.

https://www.morebeer.com/products/fermzilla-rounder-fermenter-79-gal-30.html

 

[Robeert]

Hi, I was looking for answer to same question as OP.
Back to first principles using ideal gas law as near enough for this. PV = nRT
Assuming sealed vessel (no add or loss), assuming constant volume (ignoring CO2 dissolving in beer) then
nR/V (which is assumed to be a constant) = Pressure at the start / Temperature at the start
= Pressure at the end / Temperature at the end

so Pressure at the end = (Pressure at the start / Temperature at the start) * Temperature at the end

need to use Kelvin as temperature measure and pressures need to be absolute (add 1 atmosphere to gauge value, i.e. 14.9psi at sea level)

As long as Pressure at end is > atmospheric, the plastic fermenter won't collapse.
e.g ferment at 15psig (29.7psi absolute) and 80deg F (300 Kelvin), cool to 35 deg F (275 Kelvin)

pressure at end = (29.7 psi / 300) * 275
= 27.2 psi absolute = 12.5 psi gauge.

so roughly 2.5psi drop under the example. In theory can just disconnet the spunding valve at the quick connect (sealed vessel) and chuck it in the fridge. As stated I haven't considered CO2 'loss' to being dissolved in the beer, but this could be catered for (roughly) based on volume of CO2 charts. I doubt it would upset the numbers much especially at higher starting pressures as per example.

 

[VikeMan]

All it takes is slightly positive CO2 pressure to keep the vessel from collapsing. All you're doing is backfilling the head space. I use 0.4 psi on my fermentors...

I realize I'm piling on to the revived Zombie thread, but... what kind of pressure gauge do you have that can accurately measure 0.4 PSI?

 

[Deric]

I realize I'm piling on to the revived Zombie thread, but... what kind of pressure gauge do you have that can accurately measure 0.4 PSI?

I'm pretty sure @day_trippr is using a propane regulator. I believe I saw the info he posted here about it which inspired me to use one with my Fermonster. Works great.

 

[day_trippr]

^Exactly^...

They're best used as secondary regulators...

Cheers!

 

[VikeMan]

^cool