DCHAS-L Archives, Dec 19 2018 - Re: [DCHAS-L] [New post] A note on chemical storage cabinets

If you search for the word "Teflon" in the article you get:

"However, the most effective measure involved wrapping 2 layers of Teflon tape between the threads of each glass chemical storage bottle and the cap [emphasis mine]. With this measure, the maximum vapor level was below the LOD (<3 ppm). Given these results, we tested the efficacy of the Teflon tape countermeasure on the contents of LS316. As shown in Table 3, when the bottles were sealed with Teflon tape the maximum concentration of vapors dropped to below the LOD. Thus, of all control measures investigated, wrapping with Teflon tape proved most impactful."

This follows the standard application of Teflon tape (two wraps, clockwise around the threads, as you look from the top, i.e. the same direction as the cap screws on). Note that you would need to replace the tape every time you removed the cap. I also don't think this would be appropriate if the cap had a liner gasket that was designed to seal at the lip, or if the cap is tapered; in those cases, tape would potentially interfere with the seal.

Jeff

On Wed, Dec 19, 2018 at 4:53 PM Stuart, Ralph <Ralph.Stuart**At_Symbol_Here**keene.edu> wrote:

> One of the conclusions was that resealing solvent bottles with Teflon tape brought VOCs to non-detectable concentrations. Does anyone know if they sealed under the cap (similar to how a plumber uses Teflon tape) or over the outside of the cap (similar to how chemists use parafilm)?

Good question. Fortunately, the authors also contributed an article to the Journal of Chemical Health and Safety on this work (see
https://doi.org/10.1016/j.jchas.2018.01.001 ). In this article, they describe this approach as "wrapping the threads of each solvent bottle with two layers of Teflon tape" as an alternative to "wrapping each solvent bottle neck and cap with Parafilm". They also tried putting the solvent containers in a plastic bag. As you noted, the teflon tape method did best.

So it sounds to me like they used the plumber-style approach to this.

Thanks for asking.

- Ralph

Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859

ralph.stuart**At_Symbol_Here**keene.edu

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