I just bought a Spike Flex+ which basically drained my available brewing funds. I want to brew a WCIPA with Dry Hopping. Can't afford to buy the equipment needed right now for oxygen free dry hopping. So, what if I pop the cap off the top of the fermenter, throw the dry hops in, immediately seal it back up, and then immediately start purging the oxygen from the fermenter with CO2. I could pressurize it up to a max of 15 psi, burp it with the PRV, repeat maybe as many as 10 times? How much oxygen would really get absorbed doing it this way?
Ju FWIW that is how I dry hop my beers and this 'method' works for me. It will be interesting to see if anybody can quantify the amount of air (oxygen) introduced via opening the fermenter and adding the dry hops. The actual amount will be a function of a number of variables (e.g., length of time the fermenter is opened, etc.). And how this exposure to additional oxygen and oxidation effects will be impacted by how well the live yeast in the beer 'processes' it. Cheers!
I use either a Fermonster or Speidel depending on what is available at brew day. For dry hopping, I pull off the bung, dump the hops in and reseal it. The bung is off a maximum of 5 seconds. Never had an issue. When I use to use buckets, I would crack the lid partially, dump the hops in, and close the lid. Same thing. Always worked, no issues.
I would recommend adding your hops while there is still some active fermentation happening. Not because the yeast will use the oxygen...they will already be past the point where they need it to build sterols in preparation for budding... but because the pressure difference between the fermenter and the atmosphere will carry some of the O2 out with CO2 blowing off. Of course, this will also cause more hop aroma to be carried off. Brewing is full of tradeoffs.
You can get more creative, perhaps, if you are so determined with easy supplies. It can be done in 7 steps. This is just an idea. Take all sanitization precautions as normal. The Delivery Unit 1) Take a large bore syringe (ie 60ml if needed), pull out the plunger and then smoothly cut off the end. Refine it. 2) Place the hops inside, then cover both sides with a single layer of kitchen plastic wrap and secure it so it's airtight over the openings. Poke several small holes in the layers so that they resembles the lid of a seasoning jar. **You should have what is a cylinder with hops inside ~~~~Have a Homebrew~~~~ The Delivery Method 3) Use durable non-permeable plastic wrap over the top of the fermenter, covering it like a cloak, leaving enough slack to lift the lid of the fermenter with it on. Seal the plastic cloak around the side so it's airtight. Test it! 4) Cut the right-sized hole and, onto it, seal the cut end of the entire Delivery Unit. Make the edge at the cut end of the syringe airtight against the cloak. To choose where to put the hole, refer to step 7. 5) In the plastic wrap, create an input for pressurized CO2 somewhere functional. The output will be the Delivery Unit with the plunger out. Proceed to purge and complete it. 6) Remove the cover on the Delivery Unit, align the syringe plunger and very slowly insert it into the syringe. Don't introduce room air. When it's in, and the cloak begins to inflate or is nicely inflated, stop the CO2 pressure. Make the Plunge 7) Open the lid just enough to align the end of the Delivery Unit to the fermenter opening and plunge the hops into the beer! Close the lid. Done! The plastic cover will break open and will not go into the beer. In fact, it can be cut in such a way that provides a more predictable rip. I would always suggest operating slowly so you can see that only hops enter the fermenter.
How fast does oxygenation happen? There are methods to compute this, but the people with those skills don't hang around this forum. IMO, it's closer to zero than any number that will do some harm. You have nothing to worry about if you pop an opening for a few seconds and toss in hops. To be cautious use the 1.5" port vs. 4" opening. If paranoid you can cut on your gas at 2 psi (through another port) and have it pushing the headspace gas out (slightly) while the port is open for all of what ... five seconds? The non-paranoid can skip this step. I see no need to do any burping. I'm guessing you were using buckets previously. How much oxygen infected your beer when you took gravity samples? Adding hops is much less likely to cause a problem than dipping a wine thief.
Completely agree with just pushing in a low amount of CO2 in one port while opening another port to drop the hops in during the tail end of fermentation. Once the hops are added, close up all ports and set a spunding valve to your necessary pressure for proper carbonation level. You’ll save some money on your CO2 Tank needs and retain a lot of your aromatic hop quality.
