How Seals Affect Your Brew

In the mid-1990s, as craft beers began to take over an increasing proportion of the US beer market, a giant Colorado brewer developed a novel advertising campaign. Developed in 1989 by the Adolph Coors Company as a light lager, the Keystone Light ad campaign attacked “bitter beers” and promoted Keystone Light as capable of getting rid of “bitter beer face” resulting from drinking such bad-tasting beers. The campaign seems to have been successful, as Keystone Light still finds itself among the top 20 most popular beers in the United States.

beer tapAs any true beer connoisseur knows, however, many beers have a distinctive bitter taste for which they’re known, so the basis of the television commercials was more geared towards the American preference at the time for light lagers. Yet though the bitter beer face ad campaign played to the American palate, the makers of Keystone Light were indeed on to something.

The process by which beer is brewed can negatively affect a beer’s taste. One particularly important factor affecting taste emanates from the materials used for seals within a brewer’s processing system, as certain substances react with the ingredients to affect the taste negatively. Understanding which type of materials to use for O-ring seals and O-ring sealants, along with which types of beer most affect a seal, is thus a very important factor for any brewer, regardless of their size.

O-Ring Seals in the Food & Beverage Industry

O-rings are particularly important in the food and beverage industry, and they can significantly impact product quality. This includes breweries, as when an O-ring seal’s rubber begins to break down, it can change the taste and texture of the brewed beverage. Oftentimes, a poor-tasting batch of beer may be due to a rubber O-ring seal that requires replacement rather than poor-quality ingredients. Taste can even be affected by the type of O-ring sealant used.

For this reason, many breweries have sought out the best type of O-ring, sealant, and seal to use in the beer-making process. The makeup of a seal’s materials can significantly affect the taste of any brewed product. A key aspect of this involves how the O-ring’s material swells, which can affect its ability to seal. Brewers have tried a variety of materials over the years, with fluorocarbons, liquid silicone rubber, and nitrile all commonly used in the food and beverage industry.

How O-ring Seals Affect a Beer’s Taste

Beverage applications generally utilize rubber O-rings for seals. However, when certain materials age and bleed out, they can chemically alter the product. In the brewing process, this has a negative effect on the taste of a beer. For that reason, it’s important to use rubber compounds for an O-ring seal with the lowest volume swell, affecting how well the O-ring seals.

Commonly used materials that meet FDA standards for such applications include:

  • Ethylene propylene diene monomer (EPDM)
  • Fluorocarbons
  • Heat-cured rubber silicone (HCRS)
  • Liquid silicone rubber (LSR)
  • Nitrile

In order to adequately test how well a material performs during the brewing process, it’s important not just to view the end product but also to smell and taste it. When material from a seal bleeds into a brew, often the smell will provide evidence that an O-ring seal failed. Additionally, different ingredients in beer and other brewed drinks can affect how various elastomers react; this includes ciders and sour beers, which have a higher acid content.

How Volume Swell Affects O-Ring Sealing

When testing different elastomers for an O-ring, sealing capabilities are largely defined by the volume swell of the material. When it comes to a rubber O-ring, sealing occurs best when volume swell is minimal, as those materials that expand or contract the least create the best seals. The swell seen also indicates how resistant the material is to a liquid, with less swell indicating greater resistance. Higher swell means liquids have soaked into the material, destroying the elastomer’s integrity and weakening the seal. On the flip side, negative swell indicates fluid is extracting chemicals from the rubber, which can affect the taste and shrink the size of the O-ring. Seals could then lose compression, creating leaks as the material shrinks.

Common Pump Problems from O-Ring Seals

Another aspect related to O-rings involves the pumps used in the brewing process. Known as wort pumps, having the wrong seal can cause significant issues. Often, brewers are unaware of the root problem, which involves the O-ring’s seal.

Some costly issues resulting from the use of an incorrect seal include:  

  • Leaking: This is usually the result of a problem with a pump’s seal failure. It occurs when sugars produced in the hot wort crystalize on the mechanical shaft seal’s faces, forcing the components apart and causing the pump to leak. This creates a messy situation and can lead to greater risk of corrosion.
  • Damage: When a wort pump requires repair, which will eventually happen when the wrong seal is used, it will often result in significant downtime, while also potentially wasting product.
  • Extra maintenance: While a preventive maintenance plan can help keep a wort pump running well, utilizing an incorrect seal will often result in the need for unplanned maintenance. When leaks occur, it corrodes the pump’s seals, while additionally causing damage to other pump components.

What is the Best O-Ring Seal for Breweries? 

Brewers have been testing materials for years, seeking the best O-ring sealants and O-ring seals for their applications. Generally, tests found that nitrile and EPDM changed the flavor of brewed beverages considerably while also giving off a strong smell. Nitrile did the worst with high-acid brews like sour beers and ciders, while O-ring seals made from fluorocarbons did worst with stout beers. The silicone materials, on the other hand, react least to the ingredients in brewed beverages. In the end, however, the best O-ring seal materials are those that can withstand high temperatures well while also keeping sugars from sticking to surfaces.

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