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Fermentation Vessels

What is a Fermentation Tank?

A Fermentation tank is the vessel used to house wort and yeast in the production of beer. Fermentation tanks aka fermentation vessels come in many different shapes and materials. Features vary widely based upon application and budget, but generally speaking there are three non-negotiable considerations when looking for a fermenter; The fermenter must have the ability to be repeatably sterilized, it must have some form of temperature control, and it must be able to seal it’s contents from any exposure to oxygen. The simplest fermenter commonly used is that of a glass carboy. This is almost exclusively used by homebrewers, but it does check all three boxes. Being glass, the carboy can be sanatized though the use of a sanitizing agent (commonly iodophor). An airlock or blowoff tube is used to expel the CO2 developed during fermentation while not allowing air back into the vessel. Finally some of the more technical homebrewers will place carboys in elaborate refrigerators allowing them to control temperatures. There is nothing stopping a homebrewer with this fermentation setup from making a world class beer one time. The difficulties arise in scaling from a hobby to a commercial application. 5 gallons of infected beer hurts to pour down the drain, but 50,000 gallons poured can cost a brewery tens of thousands. This is why MARKS DMW produces commercial fermentation with a variety of features reducing the risk of failure, while increasing repeatability.

What is the difference between a fermenter and a Unitank?

The main difference between a fermenter and a Unitank is that a Unitank has the ability to artificially carbonate your beer within the same tank in which fermentation occurred, while also allowing for the removal of yeast. This is somewhat of an oversimplification as we assume that a fermenter is a CCV (cylindrical conical vessel). Technically speaking, a fermenter can be any storage vessel in which fermentation occurs. Before WWI, fermentation primarily occurred in open top vessels, then a Swiss inventor named Dr. Leopold Nathan revolutionized beer production with his patent on an enclosed cylindrical fermentation tank with a conical base. Most modern fermentation tanks still utilize this design, therefore our assumption is that a fermenter is a Nathan Fermenter or CCV, whereas a Unitank is this same general design, but with an extra port to accept a carbonation stone. All Marks CCV’s are considered Unitanks.

Can I half batch in my Unitank?

All MARKS Unitanks tanks are designed to accommodate half batching. This is the practice of filling the fermenter to only 50% of it’s designed working capacity. All necessary ports such as the thermowell, sample valve, and carbonation stone are below the 50% level within the tank. That being said, MARKS does recommend a two-step crash, when cold crashing the fermenter at 50% volume. As an example, one can lower the temperature from 70F to 50F, then additionally drop the temperature to 34F. This will greatly reduce any potential for ice buildup on the sidewall of your fermenter, which can affect the specific gravity, and become a potential hazard when it breaks from the sidewall.

All MARKS Fermentation tanks are built with a 60 degree cone terminating in a 1.5” or 2” ultimate drain. The purpose of this cone is to collect the yeast after flocculation, while also ensuring the tank can be drained of every last drop of cleaning agents. During active fermentation ale yeasts are in suspension. They are happy and healthy converting sugars to alcohol and producing Co2 as a byproduct. A commercial brewery does not wish to purchase a new yeast pitch for each and every brew, therefore they need a way to collect this yeast for another use.

To do so the brewer will “crash” the tank, dropping the temperature from fermentation temps (typically 66-74F) down to 35F. The yeast will flocculate, or group together and drop to the bottom of the tank. Having a fermentation tank with a conical bottom acts as a funnel, easily allowing the brewer to capture and reuse.

A side manway offers greater tank access than it’s top mount counterpart. While MARKS does not suggest entering your tank, visual inspections on small to medium sized tanks are far easier to accomplish with a side mount manway compared to a top mount.

All MARKS tanks come with built in CIP Functionality. Utilizing a dedicated CIP arm and rotating sprayball, brewers can easily clean the interior of their fermenter with no need to enter the tank itself.  While it may sound like a small consideration, the “cleanability” of your tank design should be a major factor in qualifying a tank. Rotational sprayballs help ensure all surfaces receive adequate chemical coverage.

Fermentation can be a messy business. Krausen, a foamy head of yeast that forms on the top of wort during fermentation has the potential to clog sprayballs. When clogging occurs, catastrophic failures are often not far behind.

Many manufacturers choose to utilize the CIP arm as a blowoff arm. This means the brewer will connect their CIP arm to a blowoff bucket filled with sanitized water acting as an airlock of sorts. The assumption here is that the krausen level never reaches the sprayball as the 1/8” slits cut into a radial sprayball have a tendency to clog.

To address this issue, all MARKS Fermenters come with a dedicated 2” vent line we call a “dedicated blowoff arm”. This arm allows the tank to expel any material up to 2” in size, greatly reducing the chances of clogging. With modern craft beers pushing the boundaries of what ingredients /adjuncts are added to the fermenter, a dedicated blowoff arm can greatly reduce your risk of failure and potential injury.

A PVRV is a device which protects against over pressurization or the vacuum collapse of a tank. All sealed tanks should utilize a PVRV for safety purposes, and should be checked regularly. Inferior tank designs mount the PVRV on the head of the tank, where access can be difficult. MARKS dedicated blow off arm allows the PVRV to me mounted directly to this line leading to superior access for maintenance.

MARKS cellar tanks come standard with a #4 brushed polish finish. This is the most popular finish for stainless appliances and the food and beverage industry. This finish is best characterized by short parallel polishing lines and is well known as the easiest stainless steel finish to maintain.

MARKS cellar tanks come standard with stainless steel foot pads. While sizes very (8”, 10” and 12”) all come with up to 4” of travel. Please note that due to seismic requirements some tanks may come with fixed foot pads.

MARKS Fermentation tanks come standard with 2” of insulation on both the cone and sidewall, ensuring stable temperatures within, and increasing the efficiency of your glycol system.

Each fermenter comes with a 4” TC access port. By utilizing the 4” TC cap with integrated hop hook, brewers can add hops directly to the tank with ease.

MARKS 304SS glycol jackets are specifically designed for high turbulence and efficient heat transfer. All Fermenters come standard with a minimum of two glycol zones (cone jacket, and side jacket). Larger tanks, 40bbls and above come with multiple glycol jackets on the sidewall.

MARKS Fermentation Tanks come standard with a 1.5” TC ferrule and sanitary sample valve.

MARKS adjustable racking arm is designed with a Din Interface is built standard as a Din fitting adjustment of racking level for maximum beer recovery.

All MARKS fermentation tanks come standard with one 12” thermowell for a temperature probe. This ensures an accurate temperature reading within the tank, while reducing the potential for infection.

MARKS fermentation tanks are designed for ergonomics and ease of operation. For this reason MARKS fermentation tanks (some small tanks excluded) come with a full sweep drain.

MARKS minimum 25% headspace allows for fermentations without product loss due to foam. The aspect ratio of our tanks are always optimized for high attenuation and efficient fermentation.


Add ladder hooks to your fermenter for secure access to the top of your tank.

ASME Pressure Rating:

MARKS is an ASME U certified shop, able to engineer and manufacture tanks for pressures higher than 1 bar (14.5 psi). Breweries who wish to naturally carbonate their beers may wish to consider a tank rated for 2 or 3 bar. This allows the brewer to ferment under pressure. The Co2 produced during fermentation has no where to escape, and thus produces natural carbonation within your beer.

Rupture Disk:

While a PVRV (pressure relief valve) is included standard on every cellar tank, rupture disks are available as an optional upgrade. Consisting of a precision machined metallic disk, rupture disks are designed to fail (rupture) at very specific pressures. This design is inherently more reliable than a pvrv, but is also one time use. Add piece of mind to your brewery operations, knowing that you have a secondary failsafe for pressure related issues.

6″ Hop Port:

MARKS fermenters come standard with a 4” hop port, upgrade to 6” for greater ease of adding product.

Outdoor Rated Tank:

Standard fermenters are designed with 2” of insulation. These tanks are designed for indoor applications. For breweries looking to place fermenters in an outdoor environment subject to high or low ambient temperatures, MARKS can additionally insulate the tank, including a secondary false head, ensuring proper operation even in extreme conditions.

Colored Stainless:

If you want a showpiece in Copper, Black, or even Rose Gold we can do it! There are 70+ colors to choose from!

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