Science Buddies: "Ask an Expert"

I had to replace some black rubber washers on the sink, to which is connected my oral irrigator . . . http://www.oralbreeze.com/Oral-Breeze-Inc-RB-RediBreeze/dp/B000ODVGOM

I think it's a good idea to check the washers on all the taps once per year, because I find that sometimes the black rubber breaks down, and on your fingers, it can look like you've been handling the tip of a black magic marker. I don't want to drink that. I've been told that it's non-toxic, though.

Question: What's in tap water that breaks down a washer like that? Chlorine?

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At the local hardware store, in the faucet repair section, I see that they have white "rubber" washers.

The guy said that they're made of Neoprene or BunaN, and that the color can designate size.

Online, I see these washers in many different materials and colors (please see below).

I read that the word "washer" is a colloquial term, they're actually called gaskets.

Question:

1.) Is any "rubber" safe for a tap, out of which you might be drinking the water? How do you know? . . . For example, if I could find the green ones in the size I need, would that be ok? Maybe they're made of vinyl or silicone, which wouldn't break down.

2.) Is there any source that standardizes this (I don't see it), like: this color is this size, or made for this use

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Buna-N (Nitrile) NBR O-Rings . . . http://www.marcorubber.com/buna.htm

Nitrile - Buna N . . . Nitrile rubber is the most commonly used elastomer for O-rings and other sealing devices. Also known as Buna N, nitrile (see Figure 42) is a copolymer of butadiene and acrylonitrile (ACN). The name Buna N is derived from butadiene and natrium (the Latin name for sodium, the catalyst used in polymerizing butadiene). The “N” stands for acrylonitrile. . . . http://www.rlhudson.com/O-Ring%20Book/selecting-material12.html

White EPDM gasket / White neoprene gasket / EPDM flat gasket . . . http://beyondseals.en.alibaba.com/product/622594716-218388805/white_epdm_gasket_white_neoprene_gasket_EPDM_flat_gasket.html

Characteristic Properties of Silicone Rubber Compounds . . . www.silicone.jp/e/catalog/pdf/rubber_e.pdf

Green General HNBR O Sealing Ring Nitrile Rubber Washer Set . . . green . . . amzn.com/B00NM5U5KU

Nitrile rubber - Wikipedia . . . used in gloves . . . http://en.wikipedia.org/wiki/Nitrile_rubber

Gilmour 01CWBAG 10-Count Vinyl Hose Washers - Patio, Lawn & Garden . . . green . . . amzn.com/B0034E9XU2

Gilmour 01RW Rubber Hose Washers - Garden Hose Parts, Patio, Lawn & Garden . . . red . . . amzn.com/B000NCWP44

Silicone Flat Washers - red . . . We manufacture silicone washer in a wide variety of sizes and styles, and many colors for choice, red, blue, pink, white, transparent, etc. and we have many silicone grades for different applications, such as grade of 100% non-toxic FDA and NSF approved, grade of oil resistance, grade of unique heat resistance up to 300 C, grade of medical, etc, and hardness from shore A30 to A80. . . . http://www.ermrubber.com/Rubber-gaskets-washers/Silicone-washer-lighting-heater-pump.html

1,3-Butadiene - Wikipedia . . . 1,3-Butadiene is listed as a known carcinogen by the Agency for Toxic Substances Disease Registry and the US EPA. . . . http://en.wikipedia.org/wiki/1,3-Butadiene#Environmental_health_and_safety

Styrene - Wikipedia . . . Styrene is regarded as a "hazardous chemical", especially in case of eye contact, but also in case of skin contact, of ingestion and of inhalation, according to several sources . . . http://en.wikipedia.org/wiki/Styrene#Health_effects

Styrene-butadiene - Wikipedia . . . synthetic rubber . . . http://en.wikipedia.org/wiki/Styrene-butadiene

Dixon TRW7 White Rubber Tuff-Lite Plastic Fitting, GHT Washer . . . Styrene-Butadiene rubber . . . amzn.com/B007D5M09O

White Viton rubber washer . . . http://taishun.en.hisupplier.com/product-919693-White-Viton-rubber-washer.html

Hi sludge7051,

You've raised some interesting questions about gasket materials. I have no expertise in this area but I did a little background research that I can pass along to you.

Degradation of elastomer gaskets in contact with tap water may be caused by chlorine or chloramine (compounds of ammonia and chlorine) used to disinfect water. Carbon black is used as a pigment in some gaskets and this may be (at least part of) the “black stuff” you see when the gasket degrades.

I found a couple of articles on elastomer degradation due to contact with chloramine. Both are somewhat “dense” but interesting if you wade through them.

Loss of carbon black:

http://digital.library.louisville.edu/u ... me/732.pdf

Extensive report on elastomer degradation:

http://www.waterrf.org/PublicReportLibrary/91197.pdf

The second article listed above contains short descriptions of the various gasket materials you mentioned in your post. With regard to gasket material safety, I suggest choosing a material approved and sold for use in household plumbing fixtures.

I hope this helps. Please post again if you have additional questions.

A. Norman

Hi. Thanks! I'll take a look.

In one of the links above, they mentioned the FDA and NSF. This got me to thinking:

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I read that the FDA doesn't "certify" anything. From this page, I see that "FDA approved" is given in various contexts.

Is It Really FDA Approved? . . . http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm047470.htm

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I thought that NSF meant: National Science Foundation . . . www.nsf.gov

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health . . . http://www.nsf.gov/about/glance.jsp

. . . but it appears to really mean National Sanitary Foundation . . . www.nsf.org

Both pages bring up the same articles if I type in faucet washer, or rubber washer, rubber gasket - confusing

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I found these pages . . . I see that nsf.org is the organization that tests and categorizes everything:

NSF International Now Offers Dual Certification of Gasket and Sealing Products to Material Requirements of ASSE 1061 and ASTM F2854 for Use With Push-Fit Fittings - NSF International . . . NSF led the development of the American national standards for all materials and products that treat or come in contact with drinking water. In 1990, the U.S. EPA replaced its own drinking water product advisory program with these NSF standards. Today, all major plumbing codes require certification to NSF standards for pipes and plumbing components in commercial and residential buildings. . . . http://www.nsf.org/newsroom/nsf-now-offers-dual-certification-of-gasket-and-sealing-produts

Faucets and Other Plumbing Products - NSF International . . . http://www.nsf.org/consumer-resources/what-is-nsf-certification/faucets-plumbing-certification

Understanding Plumbing Product Marks - NSF International . . . http://www.nsf.org/consumer-resources/health-and-safety-tips/water-quality-treatment-tips/plumbing-product-markings

Listing Category Search Page | NSF International . . . http://info.nsf.org/Certified/plumbing/

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Ok, I think I have enough information on this now :-)

sludge7051-x wrote:I had to replace some black rubber washers on the sink, to which is connected my oral irrigator . . . http://www.oralbreeze.com/Oral-Breeze-I ... B000ODVGOM

I think it's a good idea to check the washers on all the taps once per year, because I find that sometimes the black rubber breaks down, and on your fingers, it can look like you've been handling the tip of a black magic marker. I don't want to drink that. I've been told that it's non-toxic, though.

Question: What's in tap water that breaks down a washer like that? Chlorine?

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

At the local hardware store, in the faucet repair section, I see that they have white "rubber" washers.

The guy said that they're made of Neoprene or BunaN, and that the color can designate size.

Online, I see these washers in many different materials and colors (please see below).

I read that the word "washer" is a colloquial term, they're actually called gaskets.

Question:

1.) Is any "rubber" safe for a tap, out of which you might be drinking the water? How do you know? . . . For example, if I could find the green ones in the size I need, would that be ok? Maybe they're made of vinyl or silicone, which wouldn't break down.

2.) Is there any source that standardizes this (I don't see it), like: this color is this size, or made for this use

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Buna-N (Nitrile) NBR O-Rings . . . http://www.marcorubber.com/buna.htm

Nitrile - Buna N . . . Nitrile rubber is the most commonly used elastomer for O-rings and other sealing devices. Also known as Buna N, nitrile (see Figure 42) is a copolymer of butadiene and acrylonitrile (ACN). The name Buna N is derived from butadiene and natrium (the Latin name for sodium, the catalyst used in polymerizing butadiene). The “N” stands for acrylonitrile. . . . http://www.rlhudson.com/O-Ring%20Book/s ... ial12.html

White EPDM gasket / White neoprene gasket / EPDM flat gasket . . . http://beyondseals.en.alibaba.com/produ ... asket.html

Characteristic Properties of Silicone Rubber Compounds . . . http://www.silicone.jp/e/catalog/pdf/rubber_e.pdf

Green General HNBR O Sealing Ring Nitrile Rubber Washer Set . . . green . . . amzn.com/B00NM5U5KU

Nitrile rubber - Wikipedia . . . used in gloves . . . http://en.wikipedia.org/wiki/Nitrile_rubber

Gilmour 01CWBAG 10-Count Vinyl Hose Washers - Patio, Lawn & Garden . . . green . . . amzn.com/B0034E9XU2

Gilmour 01RW Rubber Hose wide Pedestal Sink - Garden Hose Parts, Patio, Lawn & Garden . . . red . . . amzn.com/B000NCWP44

Silicone Flat Washers - red . . . We manufacture silicone washer in a wide variety of sizes and styles, and many colors for choice, red, blue, pink, white, transparent, etc. and we have many silicone grades for different applications, such as grade of 100% non-toxic FDA and NSF approved, grade of oil resistance, grade of unique heat resistance up to 300 C, grade of medical, etc, and hardness from shore A30 to A80. . . . http://www.ermrubber.com/Rubber-gaskets ... -pump.html

1,3-Butadiene - Wikipedia . . . 1,3-Butadiene is listed as a known carcinogen by the Agency for Toxic Substances Disease Registry and the US EPA. . . . http://en.wikipedia.org/wiki/1,3-Butadi ... and_safety

Styrene - Wikipedia . . . Styrene is regarded as a "hazardous chemical", especially in case of eye contact, but also in case of skin contact, of ingestion and of inhalation, according to several sources . . . http://en.wikipedia.org/wiki/Styrene#Health_effects

Styrene-butadiene - Wikipedia . . . synthetic rubber . . . http://en.wikipedia.org/wiki/Styrene-butadiene

Dixon TRW7 White Rubber Tuff-Lite Plastic Fitting, GHT Washer . . . Styrene-Butadiene rubber . . . amzn.com/B007D5M09O

White Viton rubber washer . . . http://taishun.en.hisupplier.com/produc ... asher.html

Thanks for the information.