Issues with Carbonation

[Spursman]

As always, sound advice from the Guru's here.

Carbing can be an issue, it certainly has been with me. After much trial, and a few errors, I've settled on 8 grams of table sugar per large PET bottle. I like a good fizz and found this about right. Previously I  was using 7 grams but since I started cold crashing it wasn't enough.

A good tip at botting time is to squeeze the bottle so the beer is just below the top then screw on the cap. This reduces any oxidation and also reduces the "balloon" effect. If you have a leakage the squashed bottle will revert to normal much more quickly than the others.

Hope this helps.

[DavidM]

5 hours ago, Spursman said:

A good tip at botting time is to squeeze the bottle so the beer is just below the top then screw on the cap.

I thought you were supposed to leave a small amount of Air space in the bottle, two inches.

Aid's Carbonation.

[Classic Brewing Co]

33 minutes ago, DavidM said:

I thought you were supposed to leave a small amount of Air space in the bottle, two inches.

Aid's Carbonation.

It certainly does need space at the top otherwise you risk 

[Spursman]

1 hour ago, Classic Brewing Co said:

It certainly does need space at the top otherwise you risk 

Not in PET bottles Phil. I've been doing this for months now with great results.

BTW Black Rock Brewing in NZ recommends this procedure. 

[Spursman]

1 minute ago, Classic Brewing Co said:

OK but I have been doing it for decades, but I did use quite a few fermentables & I always left about 1/2 to 2" but we are all free to do what we want & do whatever works for us.

I haven't used them for years & don't intend to as I keg as only use glass for the few I bottle.

Meanwhile;

https://beercreation.com/headspace-for-bottling-beer/

Of course we all do things differently, obviously you can't squeeze glass bottles. The article is referring to glass bottles. The views clearly don't apply to flexible PET bottles. 

[Malter White]

25 minutes ago, Spursman said:

Not in PET bottles Phil. I've been doing this for months now with great results.

BTW Black Rock Brewing in NZ recommends this procedure. 

As does Gash Slug on The HB Network. I did it for a short while but didn't really find any benefit to it,

[iBooz2]

3 hours ago, Classic Brewing Co said:

It certainly does need space at the top otherwise you risk 

This is just a very silly statement.  A squeezed PET bottle will always have a negative static air pressure inside,  possibly several negative psi, maybe as much as -1 bar, and it will be no doubt concaved in somewhat as a result of the squeezing and due to the subsequent difference in ambient outside air pressure to that of the negative pressure inside the PET bottle.  Think about it.

The resident yeast and sugars have to overcome this negative pressure before pressurizing the bottle and its contents by first pushing the squeezed bottle back into its normal atmospheric pressure shape (i.e. 1.013 mpa inside the PET bottle and 1.013 mpa outside the PET bottle) before it can apply further pressure to the bottles contents and carb it up.  All this is a long way away from causing a bottle bomb in a PET bottle, unless you have supplied the resident yeast with way too much sugar.

In fact, and with my long past experience (circa 1970) I would say you have FA chance of causing a bottle bomb by squeezing a PET bottle before capping it.

Yeast are amazing things.  They are probably the only living organism known to man in the discovered universe (so far) that can survive and grow in both an aerobic and and anaerobic atmosphere so hence no need for air inside your PET bottles for yeast to carb them up.

When I brew ginger beer and bottle in PET I always squeeze the air out of all the PETS before capping because the recipe is so rich in sugars and always produces a very nicely carbed up ginger beer and only ever had bottle bombs when I did this recipe in glass beer bottles of old (meaning very thick glass bottles).

Edited April 19, 2023 by iBooz2

[Spursman]

9 hours ago, iBooz2 said:

This is just a very silly statement.  A squeezed PET bottle will always have a negative static air pressure inside,  possibly several negative psi, maybe as much as -1 bar, and it will be no doubt concaved in somewhat as a result of the squeezing and due to the subsequent difference in ambient outside air pressure to that of the negative pressure inside the PET bottle.  Think about it.

The resident yeast and sugars have to overcome this negative pressure before pressurizing the bottle and its contents by first pushing the squeezed bottle back into its normal atmospheric pressure shape (i.e. 1.013 mpa inside the PET bottle and 1.013 mpa outside the PET bottle) before it can apply further pressure to the bottles contents and carb it up.  All this is a long way away from causing a bottle bomb in a PET bottle, unless you have supplied the resident yeast with way too much sugar.

In fact, and with my long past experience (circa 1970) I would say you have FA chance of causing a bottle bomb by squeezing a PET bottle before capping it.

Yeast are amazing things.  They are probably the only living organism known to man in the discovered universe (so far) that can survive and grow in both an aerobic and and anaerobic atmosphere so hence no need for air inside your PET bottles for yeast to carb them up.

When I brew ginger beer and bottle in PET I always squeeze the air out of all the PETS before capping because the recipe is so rich in sugars and always produces a very nicely carbed up ginger beer and only ever had bottle bombs when I did this recipe in glass beer bottles of old (meaning very thick glass bottles).

Exactly.  Couldnaputitbettermeself!

[DavidM]

On 4/19/2023 at 5:06 PM, DavidM said:

I thought you were supposed to leave a small amount of Air space in the bottle, two inches.

Aid's Carbonation.

I will thank the good folk here for straitening me out, I was mistaken.

No Air space needed in PET's but needed in Glass bottles.

As I only use Glass.. I'll keep doing as I do.

[Pickles Jones]

2 hours ago, DavidM said:

I will thank the good folk here for straitening me out, I was mistaken.

No Air space needed in PET's but needed in Glass bottles.

As I only use Glass.. I'll keep doing as I do.

In summary the Pet Bottle needs no air space as the expansion of the liquid can be absorbed by the flexibility of the plastic.

However, in the case of glass bottles if filled to the top any expansion of the liquid can't be absorbed by the glass and the glass will fracture or lift the crown seal top off the bottle

We are not talking about the CO2 pressure due to further fermentation, just the different temperatures bottles may experience after filling.

[Spursman]

10 hours ago, Pickles Jones said:

We are not talking about the CO2 pressure due to further fermentation, just the different temperatures bottles may experience after filling.

Really? You absolutely sure about that?

Low sugar dose equals low pressure and little fizz. High sugar dose equals high pressure and possible kaboom. Temperature only affects the rate of pressurisation surely.

[Pickles Jones]

1 hour ago, Spursman said:

Really? You absolutely sure about that?

Low sugar dose equals low pressure and little fizz. High sugar dose equals high pressure and possible kaboom. Temperature only affects the rate of pressurisation surely.

I was looking at the expansion of the liquid only due to the changes in ambient temperature. Not the effect of CO2 generation which certainly adds to the gas pressure.

[Classic Brewing Co]

15 hours ago, DavidM said:

I will thank the good folk here for straitening me out, I was mistaken.

No Air space needed in PET's but needed in Glass bottles.

As I only use Glass.. I'll keep doing as I do.

Just for the record I found this, it was mentioned earlier, I have never done it, but it makes sense, I won't be using PET's again anyway.

 

[Oldbloke]

He makes perfect sense. 

Does anyone know what the actual pressure is in a bottle of beer?

 

Hang on. Google told me.

About 36psi.

 

https://beertech.blogspot.com/2009/12/carbonation-test.html?m=1

 

Good things like beer come in glass.  

Edited April 21, 2023 by Oldbloke

[Oldbloke]

I found this on the visy Web site.

What is max carbonation 4?  

 

Good things like beer come in glass.  

[iBooz2]

Just to show you all what I am saying re the PET bottles being pseudo balloons.  Check out this pic and have a guess at what psi is in the bottle of ginger beer on the RHS.

[NBillett09]

4 hours ago, iBooz2 said:

Just to show you all what I am saying re the PET bottles being pseudo balloons.  Check out this pic and have a guess at what psi is in the bottle of ginger beer on the RHS.

At least 1psi.

[iBooz2]

34 minutes ago, NBillett09 said:

At least 1psi.

Ha har, missing a zero or two I would think.

[Oldbloke]

50psi

[iBooz2]

9 hours ago, Oldbloke said:

50psi

NAH !

Remember the smaller the volume the higher the pressure.  A bicycle tyre has a much higher pressure than a car tyre does and then a professional Olympic bicycle has way, way more than a normal street bicycle (plus it's a different gas). 

[Spursman]

11 hours ago, iBooz2 said:

NAH !

Remember the smaller the volume the higher the pressure.  A bicycle tyre has a much higher pressure than a car tyre does and then a professional Olympic bicycle has way, way more than a normal street bicycle (plus it's a different gas). 

Gotta bow to iBooze2.

He completely turns this old favourite on its head - " if you can't dazzle them with science, baffle them with bullshit".

[Pickles Jones]

14 hours ago, iBooz2 said:

NAH !

Remember the smaller the volume the higher the pressure.  A bicycle tyre has a much higher pressure than a car tyre does and then a professional Olympic bicycle has way, way more than a normal street bicycle (plus it's a different gas). 

Yes, you are correct but only if the same volume of gas is initially put in put into each tyre, they will then show a pressure differential because of each tyres volume.                                        Then, if you want higher pressures in each tyre to meet each their requirements, you will need to subsequently top each of them up to achieve it.