Must you use a spunding valve when Keg purging with CO2 from active fermentation?

[ChiknNutz]

Looking at getting a spunding valve for this purpose and maybe to try forced carbonation and/or pressure fermentation, but just wondering if you need it for the primary question. I think the answer is yes, to avoid over pressurizing or having to babysit it all the time, but just checking since I've not tried it yet.

 

[day_trippr]

Using a blow-off valve at the keg implies putting that pressure on the fermentor. No need for that.
Just feed the keg through the beer post and run an exhaust line from the gas post into a small open vessel of water...

Cheers!

 

[ChiknNutz]

Say you want to capitalize on the free CO2 so you can slightly pressurize both vessels at the tail end of fermentation to allow for pressure transfer?

 

[day_trippr]

I see - you want to build up pressure in the end-to-end system, then relieve the keg and allowing that pressure to move some beer from the fermentor.
How well that would work would depend on the fermentor head space volume and how high you took the pressure therein before starting a transfer.

That kinda math is above my pay grade. Ask for @doug293cz...

Cheers!