Dry hopping is being practiced excessively these days. Quite a few IPAs are double and triple hopped. But for a long time only pale ales and IPAs were treated on cold side with hops, but recently also other beer styles such as Pilsners or wheat beer have joined the ranks. What was originally intended primarily to improve the shelf life of beer for exports from England to the overseas colonies is now a way of adding intense aromas to beers.
But it is not enough to open the fermentation tank, throw in the hops, and close the fermentation tank again because on the other side of the coin is the potential oxygen input. We all know the brownish IPAS with honey-caramel notes right up to the cardboard flavor. In the hobby brewing sector oxidation is a big topic of discussion.
It is not for nothing that there are specially developed systems in the industrial sector for the serial production of dry-hopped beers. System manufacturers have been offering a broad portfolio in this area for several years. Such systems come by the name of the Hopgun, Dry-Hopnik, Hoprocket, X-tractor or similar.
There are many process steps where oxygen can be added to your beer. Above all, you should pay attention to this in the cold side. Due to the small sizes of our batches, even very little oxygen can have a negative effect on your beer. Systems have also been developed in the hobby sector to keep the oxygen input during the dry-hop process as low as possible. I used a normal fermenting bucket for a long time and when I dry hopped I always had the CO2 bottle in place. Nevertheless the beer oxidized on me now and then. One of the first steps I took was to get a unitank from Ss Brewtech and have been very happy with it.
If you have this fermentation tank, or a similar one with a tri-clamp connection on the lid, you can easily use the Hop Dropper. It’s a sort of sluice that allows you to flush your hops with CO2 before it drops into the fermentation tank.
It is important to distinguish whether you use a pressure-rated tank or a non-pressure-rated tank. In the first case you can flush the CO2 from the tank itself when the beer is already carbonated. Otherwise you have to flush the sluice with external CO2.
You can use my construction in both cases. It is kept very simple and consists of the following parts:
- 3-in. butterfly valve
-  3-in. gaskets
-  3-in. clamps
- 3-in. sightglass or 3-in. tri-clamp pipe
- 3-in. tri-clamp cap with pressure relief valve (PRV)
I use the 3-in. tri-clamp cap with safety valve that comes with the unitank. If you have a fermenter with a 1.5-in. tri-clamp top, you will need to swap out a few of the parts. Here are the substitutes parts:
- Reducer 3-in. tri-clamp to 1.5-in. tri-clamp
- 1.5-in. tri-clamp PRV
- 1.5-in. gasket
- 1.5-in. clamp
My approach to beers that I would like to dry hop using the example of the unitank:
- Shortly before reaching final gravity I close the blow off tube. This allows the beer to ferment and carbonate naturally. In the tank the desired pressure builds up.
- When it is time to dryhop, close the butterfly valve under the PRV. Then remove the PRV and replace it with the 3-in. sight glass or 3-in. tri-clamp pipe.
- Fill your Hop Dropper with dry hops and the PRV at the top is installed again. Make sure to fill the Dropper only about ¾ of its capacity to ensure a good CO2 flow. If you want to add more hops, it is better to split it into several batches.
- Open the butterfly valve only so far that CO2 can flow in from the tank but no hops fall in.
- Now slightly open the PRV so that the air in the airlock can escape upwards. Flush for about 1 minute like this.
- The butterfly valve is then opened completely and the hops rinsed with CO2 fall into the fermentation tank.
- Once dry hops are in your beer, you simply put the PRV back on the tank for an optimal bung.
If you are using a non pressure-rated fermenter, you can still use the Hop Dropper. Simply add 0.1–0.2 bar (2–3 psi) for rinsing, e.g. via the blow-off arm into the fermenter. Meanwhile there are some variations of the Hop Dropper. My version is very simple and effective at the same time because the hops are flushed from bottom to top to expel as much O2 as possible.