Bottling from Unitank

[Geoffrey006]

Hello,

I have recently purchased a unitank and have an isobarometric bottling machine.
I know that the pressure inside the bottling machine should be just a little less than the pressure in my unitank, but my question is how much pressure should be in my unitank during the bottling operation ? Right now I just finished carbing and I'm around 18/19 PSI. Please note that my tank is 3.5BBL and right now it's only 1/4 full, so I have a lot of co2 above the carbed liquid.

Another question : I would like to recirculate before bottling so that it's homogenous inside the tank, so that every bottle is the same. Is that ok to recirculate a carbed product under pressure ? I just connect hoses to my pump from dump port and racking arm and recirculate ? No foam will be created ? Should I vent or is it ok to leave my tank at 18/19 PSI during this recirculation ?

Thank you !

 

[Advance]

Your headspace in the unitank needs to remain at the pressure your reached during the carbonation process. If you allow the pressure to drop, CO2 will begin to come out of solution until saturation equalibrium is reached again. This will cause CO2 bubbles to form on your settled trub and lift it out of the cone and into your bright beer. Right before bottling, increase the headspace pressure 1-2 psi over the carbonation pressure through a port on top of the fermenter. Do not use the carbonation stone or a inlet/port that is submerged as this will agitate your beer throughout the bottling process. The reason why you want to add a little headspace pressure right before bottling is because your regulator will not be able to keep a constant pressure in the headspace while the beer is being transferred to bottles. Remember any dip below the carbonation pressure will cause CO2 to come out of solution, so it is best to give yourself a buffer. Very little if any additional carbonation will take place during the bottling process from this increase. Make sure your unitank is designed to operate at the pressures you are working with, a 3.5 BBL vessel at 20psi has quite of bit of stored energy potential.

I would not recommend recirculating your carbonated beer. You risk causing a great deal of damage for a possibly imperceptible improvement. Carbonating through the stone causes a bit of a mixing action to occur, if you bottle a couple days after reaching your carbonation level the beer should be mixed. Make sure you are following proper procedure for the carbonating process. If you are not, the level of carbonation you obtain as indicated by your head pressure might be false. This would result in bottling under carbonated beer if you proceed to package it shortly after reaching your head pressure goal.

This post might be of use if you are unsure of the proper process:
https://www.homebrewtalk.com/threads/carbonation-help.680106/post-8885395