From: ILPI Support <info**At_Symbol_Here**ILPI.COM>
Subject: Re: [DCHAS-L] Acid and Base (glass wash) Bath Containers
Date: Mon, 2 Dec 2019 17:28:11 -0500
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: 626BE8F6-FEA8-46E3-9FAE-404879EFFFAB**At_Symbol_Here**

My standard base bath practice was a cylindrical 5 gallon Nalgene tank on the bench top next to the sink with a loose-fitting lid.  Looked like this one:   We put netted plastic matting in the sink and sometimes on bench to reduce glassware damage.

Each 5-gallon tank had a standard mop bucket inside it, with numerous holes drilled into it, to act as a parts basket.  This allows one to pull up on the bucket handle to recover even the smallest items from the tank without having to fish around for them (except tiny stirbars, which is why God invented stirbar retrievers).  It also prevents splashing upon insertion - pull the bucket up, put your items in, and it will slowly lower itself into the tank as it slowly floods.  Very gentle and elegant.  Drips during transfer from tank to sink are easily managed by inverting the cover to use as an ersatz drip tray; simply rinse it after use.

While flammability is a concern, you can mitigate that with a higher flashpoint base bath solvent.  Saves money, too, as you are not dealing with constant evaporation versus ethanol, propanol, etc.  I am trying to remember what we settled on, but it was probably something along the lines of tetraglyme, which has a flash point of 136 °C and a bp of 275 °C according to the Aldrich SDS.  That does have a 1B reproductive toxin listing on the SDS, but when you think about route of exposure that would seem pretty remote.  It's water miscible, has low toxicity to aquatic life, and is inherently biodegradable, so for glassware washing with rinse going down the sink it's not a concern there.  You can probably buy it in 55 gallon drums for your stockroom to service multiple groups cost effectively, too.

I've used the square style Nalgene baths for sulfuric acid/Nochromix and it worked fine.  We only used it for fritted funnels so we only needed a few inches of depth there.  Chromic acid, of course, should be banned in labs given the Cr(VI) carcinogen and sewer discharge concerns.  Piranha solution is also a non-starter; I've evangelized against that numerous times here based on firsthand bad outcomes.

Rob Toreki

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On Dec 2, 2019, at 4:39 PM, Anna Sitek <asitek1**At_Symbol_Here**UMN.EDU> wrote:

Hi Kimi,

Our safety committee has had several discussions about this. I suspect our current 5 gallon bath set-ups in a secondary containment trays could be improved, but not sure how.

I like that the 5 gallon buckets can be sealed and sent for waste without an awkward transfer.  

Assuming it's just glassware going into the bath, what gas do you expect to form and build up pressure? I'm not aware of any pressurization issues. Assuming it's used for glass cleaning and not someone dumping waste into it.

Our discussions:
  • There will always be "dripping" coming out of the bath so having secondary containment area around the bath with neutralizer/ pads is recommended.
  • Containers need to be big enough to allow glassware to soak. We frequently encourage groups to use smaller baths, unless their glassware is unique and really needs large container. 
  • If large, soaking horizontally with a cover vs vertically is preferred. Deep containers have higher splash potential.
  • Some groups prefer the containers on the ground, further from their eyes, easier to lift. Others prefer on the bench top, less likely to drop something from a large distance and cause a splash. The bench top group tends to use smaller short depth rectangular containers and immediately empty them after use. The ground groups tend to leave the bath in 5 gallon buckets for re-use. 
One issue we're still wrestling with is the flammability e.g. storage in a flammable storage cabinet and transfers done in the fume hood. A parts washer or rinse tank could provide a flammable safe option but probably won't last long with the corrosion. I haven't tried but wonder if the 5 gallon buckets could fit inside of the flammable safe 10 gallon rags cans? But this still isn't addressing any potential ventilation needs. 
Commenting to see if others have found something that works well.


On Mon, Dec 2, 2019 at 1:53 PM Brown, Kimberly Jean <kimibush**At_Symbol_Here**> wrote:

Hello, and Happy December!


Have any of you issued (or been subject to) specific guidance regarding lab-scale acid and bath baths for glassware cleaning? 


After some recent spills, we evaluated the types of containers being used for acid and base baths in our labs.  Some groups are using 5-gallon buckets with poorly fitting lids, which is what led to the spills.  In updating our recommendations, however, we questioned whether or not the lids should be tight-fitting (liquid/gas tight) due to the potential for pressurization.


Ultimately, we recommended a product such as this: (Which more than a few groups resisted/rejected for a variety of reasons).


A researcher argued that there is no potential for pressurization of a base bath (e.g. KOH and IPA) during glassware soaking, and therefore, a bucket with a screw top lid should still be an acceptable option.


Thoughts?  Is there a potential for pressurization of the base bath?  What requirements, if any, do you have for this?


Thanks for sharing your experiences and opinions!


Kimi Brown

(Kimi Bush) (she, her, hers)

Sr. Lab Safety Specialist

Environmental Health and Radiation Safety

University of Pennsylvania

3160 Chestnut St., Suite 400

Philadelphia, PA 19104-6287

Office: 215-746-6549

Voice/cell/text:  215-651-0557 

fax: 215-898-0140


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Anna Sitek, CSP, CCHO
Research Safety Professional- College of Science & Engineering
Department of Environmental Health and Safety
University of Minnesota- TCEM
Lab Safety Resources
Joint Safety Team
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