Dear Mr. Wizard,
How many times can you reasonably use flexible silicone hose, the kind most homebrewers use for siphoning? I tend to start with a new hose, use it to rack cooled wort or green beer five to ten times, then convert the hose to fermentation blow-off tubes. After one use as a blow-off tube, the sucker is pretty well stained and I throw it away. Am I overusing my hoses? If not, how can I squeeze more use from them? Would high temperatures (from hot wort) running through the hose impart any off-flavors? Also, what effects does alcohol have on stainless steel? I always wipe down my equipment before and after I brew to ensure sterility. I was wondering if this practice is potentially harmful to my equipment. Thanks for the help.
Mr. Wizard replies:
The hoses used in homebrewing are similar to the hoses used in beverage and food-processing plants, except the industrial-grade hoses are reinforced to increase their pressure rating and usually covered by a durable protective outer covering to increase ruggedness in a plant environment. At first glance, a commercial-quality brewery hose looks like a completely different beast than the typical homebrew hose. But if you strip all the covering off of many commercial hoses, you will find an inside liner that is made of silicone just like your homebrew hose. Silicone is a wide array of polymers based on the structural unit R2SiO, where R is an organic group, Si is the element silicon and O is oxygen. Silicones are used in adhesives and lubricants as well as homebrew hoses. Silicone is used in all sorts of products because it holds up over a wide temperature range, is resistant to all sorts of nasty chemicals and light and is inert. The addition of different chemical groups to the basic polymeric structure of silicone elastomers can add special functions. As a result, there is a wide array of silicone polymers designed for special, severe-duty use.
The homebrewery is not a severe-duty environment and standard silicone hose more than covers the temperature range used in homebrewing (32–220° F). Silicone hose is resistant to all the standard brewing cleaners (including sodium hydroxide, phosphoric acid and bleach) and is inert (meaning it will not leach flavors into your beer). Some special silicones can have aromas; I know that some redcolored silicones have been ascribed with a fishy aroma that prompted some breweries that had these gaskets to switch to white silicone, which is aroma neutral. One way to test materials for aroma leaching is to soak a chunk of the material in beer and then smell and taste the beer.
So on to the question! I have no trouble recommending that you use a section of hose for as many times as you can, as long as the hose is kept clean and the inside surface is not cracked. Hose cleaning is one of those things that can be overlooked. If you cleaned your blow-off tube after using it with a hot bleach solution, I bet it would look like new! One half cup unscented bleach per gallon of hot tap water is a good cleaning solution.
Hoses should be cleaned by either recirculating cleaning solution through the hose (this requires a pump) or by soaking the hose in a cleaning solution. This is best done soon after the hose is used so that the soil has little time to harden inside of the hose. Many hoses have some type of barbed fitting connected to the end. It is a good idea to routinely remove the fitting and clean the area around the connection or, better yet, cut a small portion off of the hose and reattach the fitting to a smooth hose section. This helps to keep the intersection between the fitting and hose clean and the crevices in this region to a minimum. When I have a long piece of hose and am unsure if it is in good condition, I cut a piece off the hose, split the sample in half and inspect the inside of the hose. If there are small cracks, or if the hose has a build-up of beer stone (calcium oxalate deposits that appear like brown-tinted glass), I will toss it. Otherwise, there is no reason to waste good hose.
One thing to be careful about at home is pressure. Hoses that are not reinforced with braids should not be pressurized, especially with hot liquids. When silicone hose is heated, it gets soft and is easy to rupture if pressurized, for example by a pump. If you pump wort or beer, or move wort or beer using compressed gas, you need to buy braided hose. As long as the braided hose has an interior made of silicone, you can treat it like you do your non-braided hose. I have been using the same sections of commercial- grade hose continuously for the last 4.5 years without any problem.
As far as alcohol — be it ethyl alcohol (drinking alcohol) or isopropyl alcohol (rubbing alcohol) — and stainless steel are concerned, you have absolutely no problems. Do you remember the last time you were harpooned with a surgical needle? If you do, you probably remember alcohol swabs and so forth in the physician’s room. Alcohol has no deleterious effect on stainless steel regardless of contact time. The one commonly used household chemical that can really damage stainless steel is bleach. Bleach (sodium hypochlorite) is corrosive to stainless steel when the pH is less than about 12 and causes the steel surface to develop small pits. Eventually, the pits can turn into holes, transforming a pot into a strainer. Pits are also hard to clean and can be a place for bacterial contaminants to hide.
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