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Subject: Re: [DCHAS-L] plumbing H2 from remote location
Date: Thursday, October 1, 2015 11:43:38 AM
Author: Harry Elston <helston**At_Symbol_Here**MIDWESTCHEMSAFETY.COM> 		Next by Date:
Subject: Re: [DCHAS-L] plumbing H2 from remote location
Date: Thu, 1 Oct 2015 16:18:35 +0000
Author: Luis A Samaniego

From: Margaret Rakas <mrakas**At_Symbol_Here**SMITH.EDU>
Subject: Re: [DCHAS-L] Heating tape for DMSO column
Date: Thu, 1 Oct 2015 12:14:46 -0400
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: CAAszpkybeW9h7CB3cEyyUBMRS_scKL6c8DRh_ZmXrDFpyckFmQ**At_Symbol_Here**mail.gmail.com
In-Reply-To


Hi Debbie,

Please understand I am relating only my own experience, and I do not know if the grade/mfg of heating tape is the same/similar, so...your mileage may vary, this is just my personal opinion, insert usual disclaimer here...

We had a thankfully minor lab fire where heating tape was used and caught fire itself. The instructions warned (and explained why) it shouldn't be wrapped around itself; they also stated you should not leave any of the tape hanging free (remember, most of these uses are for piping), but didn't explain why. (Our students had left about 6 inches laying on a metal tray.)

When I called the mfg of the heating tape and asked why it was so important not to leave any tape free, I was told that if the tape is left free, it acts as a heat sink--the controller thinks more power is needed, the free section gets more and more power, and a fire could start. (I didn't tell him what had happened--I figured doing so would not get me any helpful answers).

So we had a sit-down with the students and explained what happened and the importance of not just avoiding overwrapping, but also why leaving a length of tape free was a fire hazard.

I also used heating tape as a grad student, and can tell you when I accidentally overwrapped, it melted the plastic coating.

I was certainly surprised at the number of hits I got when googling 'heating tape' and 'fire'.

That said, it might be the best of several not-so-great choices for your researcher. Then again, I like what others are saying about using a water jacket of some sort--what about wrapping the column with tygon tubing and running warm water through it (using a circulating bath would certainly be the most eco-conscious choice--probably in CA you wouldn't just run the tap)? If you google "Band heaters flammable solvents" (OK, DMSO is combustible, but...) you will also get some hits. I have no idea what the costs are for these-- I used one in grad school as well, and it was custom made and not that expensive (but that was, ahem, 25 years ago when I was, you know, 10).

So good luck with this project--
Margaret




On Wed, Sep 30, 2015 at 4:00 PM, Debbie M. Decker <dmdecker**At_Symbol_Here**ucdavis.edu> wrote:

Hi:

My newest researcher will be using a column purification system to purify his suite of solvents for organic synthesis. One of those is DMSO. It freezes at about room temperature. He wishes to use a heating tape to keep it gooey enough to go through the column. Here's what he's proposing to use: http://bit.ly/1WyMYFX

I'm inclined to say go ahead, so long as he installs this column at the end of the rack and in proximity to the least flammable of the other solvents. I'm also wondering if he should just have it on at low temperature all the time or wait until they have a problem and then thaw it using a heat gun. I don't like the heat gun idea, particularly, but there are also risks associated with having something heating all the time.

What do ya'll think?

Thanks,

Debbie

Debbie M. Decker, CCHO, ACS Fellow

Chair, Division of Chemical Health and Safety

University of California, Davis

(530)754-7964

(530)304-6728

dmdecker**At_Symbol_Here**ucdavis.edu

Birkett's hypothesis: "Any chemical reaction

that proceeds smoothly under normal conditions,

can proceed violently in the presence of an idiot."




--
Margaret A. Rakas, Ph.D.
Manager, Inventory & Regulatory Affairs
Clark Science Center
413-585-3877 (p)

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