In today's post, we're going to take a look at an application we've recently helped a few different customers with with counter-pressure beer cans. Increasingly, we recommend that people use Graco's FG Series air-operated double diaphragm pumps for these applications. So what is counter pressure beer filling and why are Graco diaphragm pumps perfect for these applications? Let's take a closer look.
To begin, let's start with an overview of beer filling/canning technologies in the craft brewing space. While craft breweries have historically relied on draft and draft sales, the COVID-19 pandemic has completely changed the game. Suddenly everyone needed to figure out how to get their beer into cans. There are two primary types of filling or canning – gravity and counter-pressure filling.
In a gravity filler, beer is supplied to the filler directly from the brite tank and relies on head pressure and liquid temperature to control filling. Although we use CO2 to purge cans and lower oxygen levels, because the can is open to the atmosphere, foaming can be difficult to control. This is especially true with increasingly carbonated products like seltzers.
With a back pressure filler, we pump from the brite tank to a pressurized bowl in the filler. Fill the heads and lower them into the cans and close them from the outside. The cans are purged and then pressurized with CO 2 , sealing them off from the environment. This is important because the solubility of a gas in the liquid is directly proportional to the pressure of the gas above the liquid. By maintaining constant pressure throughout filling, we can maintain CO 2 in solution and maintain carbonation levels and avoid foam formation.
Historically, craft brewers have used gravity fills due to its lower cost and greater availability. This is starting to change as back pressure filling has declined and more OEMs offer an attractively priced solution for smaller breweries.
So what does this mean for pumps? Well, as mentioned above, this means we need a bomba that can feed a pressurized filling bowl. Although the workhorse of the craft brewery has historically been the centrifugal pump, we typically cannot develop the pressures necessary to feed the filling bowl with one.
So this puts us in a PD type bomb. Looking at our toolbox, we have two main options – a Waukesha rotary lobe or a Graco AODD.
While the Waukesha Universal Pump can get the job done, there are some drawbacks. On the one hand, we have general footprint. Typical Universal 18 or 30 pump sets will be between 36″ and 60″ long and 24″ to 36″ wide. Rotary lobe pumps also feature a mechanical seal, which means an opportunity to capture oxygen. We also have to be careful not to decapitate them. They also require three-phase power, which not all breweries have readily available. Finally, a PD pump assembly is not cheap, typically costing between $10,000 and $12,500 after adding the gearmotor, base, and variable frequency drive.
Graco's FG series of AODD, on the other hand, is extremely compact and easy to use. Just connect your hoses, connect the air and you're done. We also don't have to worry about an AODD blocking. And there is no mechanical seal to allow oxygen in. The push/pull action of an AODD is also low shear and gentle on the beer. Finally, Graco FG series pumps cost about 1/3 the price of a comparably sized rotary lobe assembly.
So whether you're a brewer trying to decide between counter pressure and gravity filling or you're an OEM designing the latest and greatest counter pressure beverage filler, consider a Graco AODD. In addition to being compact, easy to use and economical, Graco AODDs are gentler on beer and eliminate at least one source of oxygen pickup, while still handling the higher pressures required for backpressure beer filling.
Credits: https://triplexblog.com/2022/07/01/graco-aodd-case-study-counter-pressure-beer-filling/
