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Subject: Gaskets and alcohol

Gaskets and alcohol

From: Louis Sorkin <sorkin<-at->
Date: Friday, November 20, 2009
Does anyone have any information on gaskets and alcohol storage (for
specimens)?  Below are three that I know of in use or suggested for
use (info from a manufacturer's website).  We have clamp-type mason
jars and the gaskets normally supplied with those are for food
storage use and the rubber or neoprene or whatever material is
normally used will leach out phthalates over time.  The gasket can
become gooey, hardened, discolored and the alcohol also discolors
and becomes "greasy" or cloudy.  The typical green, white, black,
red or pink stoppers sold for alcohol specimen storage also end up
like the gasket although I've not seen green gaskets.  The newer
green stoppers often swell many times their original shape.

    Nitrile
    (NBR/Buna-N Butadiene Acrylo-Nitrile)

        General Temperature Ranges: 0/+240 deg. F

        Generally resistant to: Most Hydrocarbons. Fats, oils,
        greases, hydraulic fluids, chemicals, and solvents.

        Generally affected or attacked by: Ketones, esters,
        aldehydes, nitro, and chlorinated hydrocarbons. Ozone, polar
        solvents, and MEK.

        Nitrile is best known for its uses where oils are present.
        It can also be produced in white with FDA ingredients.

    Silicone Rubber
    (SI/Siloxane)

        General Temperature Range: -60/+460 deg. F

        Generally resistant to: Moderate or oxidizing chemicals.
        Ozone and concentrated sodium hydroxide.

        Generally affected or attacked by: Many solvents, oils,
        concentrated acids and sulfurs.

        Silicone can be used for its excellence in outdoor
        applications and provides higher temperature resistance, has
        natural flexibility, and excellent sealing performance. Also
        available with FDA ingredients.

    Viton
    (Fluorocarbon/Fluorinated Hydrocarbon)

        General Temperature Range +10/+450 deg. F

        Generally resistant to: All aromatic, aliphatic, and
        halogenated hydrocarbons. Also many acids, animal and
        vegetable oils.

        Generally affected or attacked by: Ketones, esters, and
        nitro containing compounds.

        Viton is known for its higher temperature resistance along
        with the ability to withstand many solvents, acids, fuels,
        and oils.

Louis N. Sorkin, B.C.E.
Entomology Section
Division of Invertebrate Zoology
American Museum of Natural History
Central Park West at 79th Street
New York, NY 10024-5192
212-769-5613
Fax: 212-769-5277


                                  ***
                  Conservation DistList Instance 23:19
                 Distributed: Sunday, November 29, 2009
                       Message Id: cdl-23-19-018
                                  ***
Received on Friday, 20 November, 2009

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