Note: This info was in multiple posts in Forced to use 1/4" (not 3/16") for 15' beer line? thread but it's lost in there so I'm reposting here for easy reference as the subject seems to come up a lot.
4 taps with 12-15 feet of beer line on each to a freezer set to 40F. 5-6 feet of line is outside the freezer. Shanks and beer line are chilled to 40F using a cooper loop circulating a coolant fluid. More info & pictures here
Poly vinyl chloride (PVC), or 'vinyl hose' - Flexible, easy to work with, wall is usually very thick when using for beer:
Polyethylene, or 'poly tubing' - Hard and unflexible, wall is usually much thinner than vinyl:
All vinyl line seems to cause some 'plastic' taint if the beer sits in it long enough. In my setup when vinyl line is used the first 2-3 oz has a plastic taste if I go more than 3-4 hours between pours. Happens with light lagers to heavy IPA's. All lines and taps have been cleaned, sanitized, etc.
Makes no difference if the line is 'food grade' or not. Food grade does not mean that it won't impart a flavour to the substance passing through it, it just means that it meets certain FDA standards. None of the NSF standards guarantee either that a taint won't occur. The two that are the most brought up in reference to beverage use are:
NSF 61: Certification applies to materials for use in the conditioning, filtration and transport of drinking water.
NSF 51: Certification applies to materials used in the production or delivery of food and beverage products.
More information: www.NSF.org
Speaking to the engineers who manufacture industrial beverage line at Kuritec/Kuriyama and Arrowhose, it seems that the only way to get rid of this taint is to use what's called 'barrier tubing'. Barrier tubing is poly tubing with a glass-like barrier in it made out of PET (Polyethylene terephthalate) material, the same stuff that plastic pop bottles are made from. Barrier tubing is usually used for setups where the lines aren't 100% dedicated to a certain beverage. You can actually go from pop -> milk -> cranberry juice without any cross-taints as long as you flush the lines properly in-between.
I tested multiple types of vinyl hose and poly tubing. Testing was done by leaving water in each hose/tubing (not connected to anything) for 24-48 hours. The water was then tasted and compared to regular tap water.
(1) Defective morebeer.com 3/16" generic clear vinyl hose:
This line was the reason I started on this quest. As it turns out, I had received a defective batch of their 3/16" vinyl hose that wasn't made to spec and caused more of a plastic taste than usual. Horrible plastic taste, even after beer or water has sat in it for only 2 hours. There's no way anyone would find this acceptable. The hose in unmarked so I do not know who's hose they use (morebeer.com would not make it themselves of course). Instead of getting it replaced they simply refunded me so I could not compare it to non-defective hose.
(2) Arrowhose.com 3/16" type 14 clear vinyl hose:
Some taint. Less than (1) which is expected as (1) is defective. (2) is probably what most people use or are used to. This hose type is used and sold at many places. NSF-51 and FDA (food grade) compliant. A local draft installer in town has done 700 installs with this stuff.
(3) Arrowhose.com 3/16" type 14 clear vinyl hose:
Second sample of the same hose as (2), bought at a different location, different batch. Still some taint just like (2) above. I wanted to try a second piece just to be sure.
(4) Generic clear vinyl hose from Home Depot
: Worse than (2).
(5) Simgo.com generic 3/16" clear vinyl hose:
Same taint as (2).
(6)Kuritek Bevlex Series 200 Clear vinyl hose:
Same taint as (2) more or less. May be just slightly less. This is the best vinyl hose according to the Kuritek engineer I talked to. He uses it in his own own home bar.
(7) Arrowhose.com 1/4" type 58 poly tubing with "flo-guard" barrier:
Very subtle plastic taint. Much less than all above. This tubing uses a PET inner lining. NSF-51, NSF-61, FDA food grade. Not available in 3/16" size. Here's an online brochure
about their "flo-guard" type tubing.
(8) Arrowhose "type 5C" grey poly tubing:
Very subtle taint. Less than (7), much less than any of the vinyl hose. This is an odd tubing, one that I basically purchased by accident: One supplier told me that he could get 3/16" Arrow type 58 but I was sent this stuff instead. It's a custom order type tubing made once in 2001 without any barrier at all. I only include it here for reference purposes.
(9) Generic Home Depot 3/16" white poly tubing:
Very suble taint. Less than (7), much less than any of the vinyl hose. Very similar to (8). This is similar to what most people would use to do a water line for a fridge with water in the door and/or a built-in ice maker.
(10) Kuritek.com 1/4" Bev-seal Ultra Series 235 poly tubing with barrier:
NO plastic taint at all! This tubing uses a PET inner lining. Note that Bev-seal Ultra series 235 is not available in 3/16" sizing even though their website indicates it is (I spoke to their engineers and it has never been produced in that size).
Conclusions / Comments
1. Most vinyl line is not that bad, most people will either not care or simply pour off the first 2 oz or so as it likely won't be cold anyway unless your entire system is chilled.
2. Poly tubing is better than vinyl in all cases.
3. Number (10) (Kuritek.com 1/4" Bev-seal Ultra Series 235 poly tubing with barrier
) is by far the best and the only one that didn't leave any taint at all, even after extended periods. It's what I use now. Beer can sit in the line for 2 weeks and the first 4 ounces that sat in the line tastes the same as beer from the keg.
Not everyone can use 1/4" line and still have a balanced system due to the lengths required at the regular pressure of around 12 PSI as 1/4" has considerably less restriction than 3/16" line. To make matters worse, the glass-like PET coating on barrier poly tubing reduces restriction even further. I however like my draft beer served like in the pubs: A bit less carb'ed than bottled beer. I keep my Ales at around 3-6PSI and pump through about 8'-10' of the 1/4" poly tubing, and my lagers and wheat beers at around 5-8PSI and push through 12-15' of 1/4" poly tubing. This works great for me with 1/4" poly line and keeps the whole system balanced. (No need to adjust the regulators, ever).
I bought the Kuritek.com 1/4" Bev-seal Ultra Series 235 poly tubing from Simgo.com in Mississauga Ontario Canada for $0.21/foot CDN (US/CDN exchange rate is more or less on par). No idea if they ship to the US. Simgo.com is reseller distributor but they do also sell to enthusiasts directly if you ask. You have to call, there's no ordering online. In Canada shipping is dirt cheap even for large orders (I've never paid more than $7 for a large box) and it always arrives the next day via courier for me as I'm in the same province. Their prices are typically 1/2 of what you'd pay at resellers of beer equipment. If they won't sell to the US, call up Kuritek and find out who their distributors are and then bug them for places that sell their Bev-Seal tubing.
4. A word of warning when using poly tubing. The stuff's a lot stiffer than vinyl so it's harder to work with and leaks are easy to create. You need to make sure that the barbed ends you work with are good and sharp so that you can get a good fit and USE HOSE CLAMPS! 1/4" poly fits directly on to 1/4" barbed disconnects and shank nipples. Poly doesn't have the same stretch as 3/16" vinyl, but you can make 3/16" poly fit over a 1/4" barb if you hold it in boiling water first for 30 seconds and then push it on very carefully to not crink it.
5. Some people have told me that this 'taint' is all in my head and that they use the same type of vinyl that I've tested and do not notice any off-tastes. It could be that the amount of taint that vinyl line produces is reduced over time. I did not however notice any difference over the 3-4 months that I used the (2) vinyl hose. As for it being in my head, I had a few other people (brewers and non-brewers) taste water samples without telling them which hose they came from, nor did I mention what the off-taste tasted like. I had them rate them and most people rated the order the same as me, and noticed what they called a 'plastic' or 'rubber band' or 'rubber boot' taste. If you don't notice it yourself, good for you! Enough others have posted recent threads on the subject that I don't think I'm alone.