Yeast stalled from pressure?

[DuncB]

Assuming from the above that you have a butterfly valve and then a 3 inch sight glass that you are using for the hop dropping?

 

[refect]

Yes, the main top port of my FV has a 3 inch butterfly valve mounted to it. I attach a 3 inch site glass with a 3 inch cap on top that has a ball lock gas post and standard pull pin prv mounted on it, so I can easily purge with co2 before dropping hops.

Lately I haven't really been using the site glass as much unless it's a large amount of hops going in at once. I can easily fit about 2 oz of hop pellets into the space of my 3 inch butterfly valve, and put the gas ball lock/prv combo cap on top of that to purge with co2. I may have to do it several times if it's a 4-6oz addition, but it's one less thing to clean/sanitize before and after. I now save the site glass for the bigger hop additions.

 

[DuncB]

I don't have a hop dropping system on my PET fermenter, so I just suspend the hops in bags using sous vide magnet inside and a hard drive magnet on the outside.
I suppose you could put the hops in the top of the butterfly valve and PRV on top but have the valve cracked open enough so the hops purge with ferment CO2 and then drop in. Or do the same on the occasions that you use your big sight glass.

 

[refect]

I don't have a hop dropping system on my PET fermenter, so I just suspend the hops in bags using sous vide magnet inside and a hard drive magnet on the outside.
I suppose you could put the hops in the top of the butterfly valve and PRV on top but have the valve cracked open enough so the hops purge with ferment CO2 and then drop in. Or do the same on the occasions that you use your big sight glass.

This could certainly work as well. I used to do the sou vide magnet and bag method whenever I use my anvil bucket fermenter. It worked really good! However, I recently converted it to use a bigger cooling coil for better coiling than the small one it came with. The top hole that the cooling coil goes in was available, so I decided to attach a weldless 1.5 inch tri clamp port to the hole on top to drop hops and other adjuncts in like I do on my unitank.

 

[bloombrews]

I brewed up a west coast style IPA last week and decided to test out my new spunding valve with this batch (First time ever spunding a batch). I didn't want to start with pressure right off the bat because I'm not spunding to lower ester producton. I just wanted to capture co2 and preserve hop aromas.

About 48 hours into fermentation I was having some pretty good activity, so I decided to close the valve on my blow off arm and wait for pressure to build naturally. I was trying to achieve 15 psi, but it seems the yeast could only get it to about 13ish psi before it seemed to stop building pressure. After a few hours of waiting to see if pressure was going any higher (it didn't), I called it good an started to open my spunding valve until it started bubbling. I then dialed it back a bit so that I was holding a steady 13 psi on the pressure guage.

@refect
You must put an accurate pressure gauge on the fermentor along with the spund valve. If any of your gaskets or tri-clamps are not holding higher pressures, the gas will leak out to the point of below your spunding valve set point. Don't always trust the one gauge that you may have on it. Could be off a few pounds and that is all it takes to get below your set point, and no more visual gas release, due to the high pressure leak.
I periodically test my Unitanks with compressd air over 24 hours to see if any drop. If I see a noticable drop, I soap test all the fittings (especially above the beer/wort level).