How do Hop Cannons Work?
I was speaking with Chris and workshopping ideas for an article and we came up with an interesting topic on, How Do Hop Cannons Work? The fact, I ordered a hop cannon this month, it seemed appropriate to write about them.
I’ve worked with a few different designs of hop cannon over the years, and even used a Braukon hop cannon. This is the original which all other cannons are based off. Hop cannons are used for dry hopping beer.
Brewers dry hop beer to add aroma to beer. Adding hops on the cold side (after the wort has been chilled) prevents hops from volatizing and the essential oils from evaporating out. The net result of dry hopping is added aroma without any additional bitterness.
Although there are brewers who believe, including Scott Janish if the IBU of the beer is below 30 IBU’s, dry hopping can increase bitterness. However, I digress let’s start with traditional dry hopping methods.
Traditional Dry Hopping Method
The traditional dry hoping method is to open a port or manway of the fermentation vessel and literally dump the hops in to the wort. Brewers have different processes and thoughts about when to add the hops, but the actions are still the same.
This method is the simplest way to dry hop, but it presents two major issues which are oxygenation and safety. Dumping the hops in like this, can cause the dreaded “hop volcano”.
Dry Hop Volcano!
A hop volcano happens because CO2 produced during the fermentation breaks out of suspension due to nuclearization, by the addition of hop matter. It’s like adding mentos to Coca-Cola.
When you dump hops into the beer it’s often a race to close the fermenter port/manway before beer rises and sprays everywhere.
Now, there are ways to counteract a hop volcano like adding a few pellets first, then closing up the FV and then adding the rest of the hops later. However, as you can see from the video it dangerous, especially if when using a ladder.
Oxygen Pick Up
The other issue is oxygen pick-up. If you’re adding hops after the end of primary fermentation, opening the FV up can allow oxygen pick up.
Oxygen pick-up is deadly to beer. If you’ve had a beer which tastes like cardboard, then you’ve had oxidized beer. Also, opening the FV increases the risk of particulates entering the brew too.
One way to counteract oxygen pick up is to add the hops just prior to end of fermentation.
This helps in the following ways:
- There’s still some primary fermentation to go, so more CO2 to be produced, this can help avoid oxygen pick up after opening the FV.
- As there is still movement in the beer due to active fermentation, it can help mix the hops allowing for better aroma pick up.
- There’s a belief dry hopping before terminal gravity guards against hop creep too.
Now, of course there are downsides to adding hops before the end of fermentation, it can increase the chance of a hop volcano. Plus, if the fermentation temperature is too hot, some brewers believe it leads to undesirable aromas.
The hops are usually left in the FV for 4 days, if you leave them for longer, undesirable grassy aromas can form.
The hops are usually dumped from the bottom of the FV outlet to the drain. In some countries though, you need to collect the spent hops for proper disposal.
Due to the above issues with traditional methods of dry hopping, brewers were seeking alternative methods, leading to the invention of the hop cannon.
How do Hop Cannons Work? What Is a Hop Cannon?
Before we look into how hop cannons work, I think a little explainer of what they are is advisable. A hop cannon is a piece of brewing equipment to effectively dry hop your beer in a closed-circuit environment.
The hops are placed inside the cannon, they are on the outside of a stainless-steel candle which act as a filter. So, when the beer is introduced and recirculated it then flows back to the FV, with the hop matter is contained in the cannon.
You run the cannon recirculating the wort, for a minimum of four hours, testing the beer throughout for sensory analysis. When you have the desired aroma, you can stop the recirculation of the beer through the hops and push all the beer back to the FV with CO2.
It means the desired hop aroma is added in one day rather than 4 days with traditional methods. Plus, as this process takes place in a closed CO2 circuit, there’s much less oxygen pick up than with traditional dry hopping methods.
You can push the beer back to tank with CO2 added to the top of the cannon
Now we know what a hop cannon is, let’s answer some common questions, I get asked about hop cannons. So, we can understand them better.
Hop Cannon Q&A
Do you use it for dry hopping?
Yes, I know we’ve already gone over this question, but it’s a good lead in question. Hop cannons are used for dry hopping. Furthermore, I’ve trailed adding finings at the same time. I used SB3 in my trials.
I liked the idea of killing two birds with one stone. I added the finings in the last hour of the run, this allows me to mix the finings thoroughly with the beer.
The addition of SB3 for me didn’t affect the aroma of the beer. I’ve trialed this several times and been happy with the results.
What is The Maximum Number of Hops You Can Add and the Maximum Volume of the Cannon?
You can get hop cannons of different sizes, it’s down to what beers you brew and the maximum hop load they require. Also, many brewers use 25% less hops when using a cannon than if dry hopping with traditional methods.
Please note the price of hop cannons isn’t logarithmic, as 600-litre cannon isn’t twice the price of a 300-litre cannon. The work to fabricate one is similar so, you’re paying for extra materials.
So, if you’re looking to expand to bigger tanks in the near future, it’s worth investing in a bigger cannon. The caveat being the minimum number of hops used when running a cannon is 30% of total maximum hop load for good results.
For example, if the maximum hop load of your cannon is 50Kg of hop pellets then you’d need to use a 15Kg of pellets at a minimum for good results.
Please note: See the table below for more information on hop loads…
What’s the Max grams per litre (g/l) of pounds per barrel (lbs per bbl) you can do with a hop cannon?
Again, it down to your needs and recipe. All hop cannons have a maximum load, for instance the one pictured below, which I’ve used is from Bespoke Brewing Solutions (BBS).
These are the guys (John and Justin) who appeared on the recent Brewery Layout Video (insert link to brewery layout video).
In fact, BBS have a special offer for the Build Me A Brewery readership of this post. Get 8% off a hop cannon from them by quoting “BMAB8”, click here to contact them directly
The cannon below is a 180L cannon and is rated for a maximum hop load of 25Kg, although some brewers have pushed this to 30Kg. So, depending on the volume of the beer in your tank it gives you your maximum grams per litre.
See the table below for the 180 litre Bespoke Cannon, as you can see with a 25Kg pellet maximum with a 1,000-litre vessel gives you 25 grams per litre (g/l) and 10 g/l with a 2,500-litre vessel.
Furthermore, with a minimum load of 6.25Kg (30% of max load), the minimum g/l for a 1,000-liter tank is 6.26.
However, as always in brewing, there are a few caveats:
As we said many brewers use 25% less hops when using a cannon, as they believe this method is more efficient. Also, the longer you run a cannon, you can get more aroma.
How Many Hops to Use?
In traditional hopping methods the guide is 10 g/l for IPA’s and 15 g/l for DIPA’s (double IPA’s) using T-90 pellets. With a cannon using T-90 pellets it could be 7.5 g/l for IPA’s and 11.7 g/l for DIPA’s.
The longest I’ve run a cannon is 8 hours, I was basing it off sensory analysis. Typically, you run a cannon for 4 to 5 hours. So, it’s a full-day with preparation and clean down.
How do Hop Cannons Work? – How Long Do Your Circulate For?
Yes, we’ve briefly answered this question, but to add some meat to the bones, I use Braukon’s recommendations. They say you needs to recirculate until you’ve done 5 times your total volume tank volume.
So, in a way it depends on the power of your pump. You need to know the maximum speed of you pump. For example, if the pump works at 2,000 liters per hour and you have a 1,750 liters tank then you need run the hop cannons for 4.4 hours
1,750 * 5 = 8,750 à 8,750 / 2,000 = 4.4 hours
However, this is just a guide as the pump might not work to maximum speed, that’s why you usually go by sensory. So, run the hop cannon until you’re happy with the aroma profile.
What Temperature is the Beer at When Using the Cannon?
This is truly personal preference; all brewers have their own beliefs and methods. I usually run a cannon at 17°C (62.6°F). I also set the temperature of the FV (temp set for glycol to kick on) to the same temperature so the beer doesn’t heat up during the run.
Generally, the warmer the beer the more aroma will be picked up. Most brewers tend to dry-hop in the 17 to 21°C (62.6 to 69.8°F) range. Although, some brewers I know dry hop at 10°C (50°F). I like 17°C as it leads to less chance of polyphenol extraction, astringency or hop bite.
How do Hop Cannons Work? What Speed a Pumps Run At?
I always run the cannon at the fastest speed the pump will go at. The recirculation runs under pressure and I want to create good vortex to get the maximum aroma from the pellets.
Furthermore, this is the advice of Braukon, they say higher turbulence prevents the candle from blocking.
Extra Tip: Never spund a beer you intend to use with the cannon. It can lead to larger CO2 break out and excessive, dangerous pressure when the cannon is running.
Can You Give Us Some Insights into Pressure When Using the Cannon? How do Hop Cannons Work?
Again, this is only from my experience. I followed Braukon’s advice when first using their cannon, and it didn’t work for me. The pressure in the cannon itself always got too high and the pressure relief valve (PRV) would open spraying beer everywhere!
As mentioned before over time the candle gets a little clogged with pressure starting to rise in the cannon. So, I’ve found the best workaround it to start with 4 PSI (0.27 Bar) or even lower in the FV/unitank where the beer is being held.
This is much lower than recommended by Braukon, however over multiple runs and with different hops cannons this has worked for me. I’ve not had beer spray everywhere.
Furthermore, I’ve not had more oxygen pick-up as a result. Using this method, the maximum pressure I’ve had in the hop cannon is 25 PSI (1.7 Bar). Which is high but still within safe parameters, which is anything under 30 PSI (2.0 Bar)
Please note: Check with your manufacturer the safe working pressure of you hop cannon. If you get too close to this pressure then stop the cannon. One work around is to push the beer backwards with CO2 (a little bit) to unclog the candle and try again.
As I said before dump out as much trub, sediment and yeast from the beer before you run the cannon to help prevent pressure build up.
Also, if pressure does start to build in the cannon and the FV. You can reduce the pressure in the FV, which will lower the pressure in the cannon too.
Have You Ever Noted Undesirable Aroma When Using the Cannon?
Personally, no I haven’t. The rules of brewing still apply you get out what you put in. So, results depend on the hops you use. Furthermore, hop aroma still develops after the initial use of the hop cannon.
The initial aroma after the run is like raw pellets, over the next 3 to 4 days this aroma evolves. I don’t chill my beer until 3 to 4 days after the cannon run. People will say “Neil, the cannon is supposed to make the turn around time quicker”.
Yes, that’s true, but I’m just sharing my experiences and other brewers will have their own methods. I can only go off personal experience of using a few different cannons. Also, once you add CO2 to the beer after the run, I find the aroma tends to “pop” more too.
It’ll come down to your own experiences how you use a cannon. Whatever, the process just factor timings into your brew schedule.
Furthermore, it’s worth noting some hop matter does go through the candle into the beer in tank. It’s a small percentage, but I’ve seen it with all hop cannons I use.
How do Hop Cannons Work? Have You Seen DO (dissolved oxygen) Pick-up?
With the Braukon cannon we saw minimal DO pick-up. We had an Anton Parr CboxQ and we could still get below 30ppb with a pale ale, hopped with the cannon when packaged into 330ml bottles.
With the Chinese versions including the Bespoke Brewing Cannon, we didn’t notice and O2 pick up on sensory when drinking the beer a few months later. I can only offer anecdotal evidence as we didn’t have a DO meter to check the numbers.
With good practices when running the cannon, you can keep DO pick-up down. You CO2 purge the cannon before using it. I also feed into CO2 from the bottom of the cannon when putting the hops in.
What Type of Pump do You Use?
I simply use my CIP pump when using the cannon. If it has VDF control even better, but as I say you run the pump at full speed anyway. Still, it’s nice to have some control of the speed. I’ve never had an issue using a CIP pump with all cannons I’ve run.
Do You Measure Outlet Pressure Through the Run, as it Indicates the Candle is Blocked?
All hop cannons have a pressure gauge to measure the internal pressure. Any beer which has been fermented has some CO2 in it. Running a hop cannon will lead to some CO2 breakout, it’s unavoidable.
When you run the cannon, there’ll be some sediment/yeast build up on the candle. If this happens then you’ll see a pressure increase. So, before using the cannon it’s best of you’ve dumped as much sediment from the bottom of the tank beforehand.
As we said earlier this is why you run the cannon as fast as possible. With pump going full-speed the turbulence helps keep the candle from blocking. Make sure the hop cannon you buy has a pressure release valve (PRV); this is a safety feature. It means if the pressure is too high, the PRV opens automatically.
It’s not ideal as it means beer will spray out of the top but, it’s better than a cannon under too much pressure. If this happens turn off the pump off and wait for the pressure to go down. Your choice then is to try again, or attempt to push the beer backwards to unblock the candle.
How do Hop Cannons Work? Is the Filter Removable for Cleaning/Replacement etc.?
With all the hop cannons I’ve used, all parts can be disassembled, broken down and cleaned. It’s much like a unitank, where you take all the parts off and clean them when doing a CIP.
The candle/filter can be taken out and cleaned. It should be done as it’s the easiest way to clean off the sediment stuck to it.
Once you’ve cleaned and rinsed out the sediment out of the cannon and from the candle, you can put it all together and do a regular CIP. It has its own CIP spray balls in place.
What Beer Losses Do You See with Using the Hop Cannon?
Typical losses when using traditional dry hopping methods is between 5 and 7 litres per kilogram of hop pellets used. It’s less with the cannon, I don’t have exact figures and this is anecdotal evidence from me.
I have managed to package more beer when using the hop cannon compared to using traditional methods, when using the all the other same processes in a brewery. This can be accounted for by:
- Using less hops (25% less)
- The hop matter is left behind when using the cannon and you can push all the beer back to the vessel
- You have to do several dumps of yeast, hops and sediment when using traditional methods so, you’ll lose some beer too.
- Less beer is “soaked up” by the hops in the cannon, compared to sitting for 4 days in the tank with traditional methods
It’s hard to put a figure on the beer loss at the smaller craft beer level, but it’s under the 5 litres a kilogram of traditional methods. According to the rudimentary data tracking I could do using Ekos. The software I was using when I was operating the Braukon.
How do Hop Cannons Work? Conclusions
So, the ultimate question I get asked is…
“Would you recommend a hop cannon?”
Yes, I like them, and as I say I literally ordered one this week from the guys at Bespoke for a brewery I’m working with. Here’s why…
- Can use less hops
- Less hop material in the tank
- I can fine the beer at the same time
- Less change of oxygen ingress in a closed system
- The cannon from bespoke comes with a carbonation stone which could be useful
Oh, and one more thing, it can be used with other additions as well as hops. Many breweries use it for coffee plus, it can also be used with fruit, tea, different spices or herbs.
If you’re a very small brewery, say with tanks less than 1,000 litres then it might not be for you. However, if you’re at 1,500 litres plus then I’d day it starts to become an attractive option.
Just to remind you, Bespoke Brewing Solutions are offering 8% OFF a hop cannon to the BMAB readers of this post. Click here to contact them directly and quote “BMAB8” to take advantage of this offer…thanks BBS!