Spunding valve CO2 capture pressure build time

[Off Balance Brewing]

I'm looking to try my first CO2 capture for continuous purging the serving keg. Looks like a couple threads detailing the set up for ferm kegs is to hook the ferm gas in to the serving beer outlet then hooking the spunding valve to the serving keg gas in. That set up really increases the head space. I'm wondering if it takes longer to build pressure and can cause the krausen to raise up and blow into the serving keg. I don't think I have to be worried about the extra oxygen headspace starting from the serving keg when fermentation starts, but does the large head space cause a long delay in pressure build? I ferment in kegs and put the wort up to the weld line to maximize the batch. Usually krausen blowout isn't an issue at 15 psi, but it ramps pretty fast with a small head space.

 

[ChiknNutz]

For me, I usually see pressure within 12-24 hours, but I haven't really watched to see exactly when. I use a 7.6G kegmenter which has plenty of headspace for the beers I've made so far, never had krausen enter the line to the keg.

 

[Off Balance Brewing]

Yeah if I was fermenting in something larger than a keg I think it would be fine. But 5 gallons of head space makes me worry the krausen won't stay down.