Sulaiman
International Hazard
Posts: 3734
Registered: 8-2-2015
Location: 3rd rock from the sun
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How to safely open HDPE bottles with cap inserts.?
Most liquids that I receive are in HDPE bottles with this type of cap and insert.
They mostly seal well, but opening them has presented a couple of hazards:
Internal vapour pressure can POP the insert out when the cap is unscrewed.
Not necessarily immediately, sometimes there is a delay,
...A wet insert and little drops of liquid travel in the general direction of my face.
(So I remove the cap with an old cloth covering the cap and top of bottle)
I pull the inserts out using a fingernail, so I often get small quantities of liquid on my finger.
Gloves can be punctured between my fingernail and the bottle/insert gap.
(This is my main concern)
Anyone got a tip/trick/tool that they can suggest. ?
I wear eye protection (almost) always,
unless staining, toxic or hazardous chemicals are in use, I work without gloves
[file]103277[/file]
CAUTION : Hobby Chemist, not Professional or even Amateur
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paulll
Hazard to Others
Posts: 112
Registered: 1-5-2018
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Mood: It's fine. Really.
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Maybe look up, "spudger," on ebay or the like? Sold dirt-cheap as pry tools for electronics, but perfect for the job, as long as whatever you're
opening is compatible with nylon. They're commonly in steel, too, but a bit more hit-and-miss as to whether you're getting a pry-tool, or a
butter-knife...
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Precipitates
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Posts: 137
Registered: 4-12-2023
Location: SE Asia
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Mood: Acid hungry
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An old small knife - but yeah they can be annoying at times
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jackchem2001
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Posts: 51
Registered: 2-6-2024
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This will not help with chemicals you are receiving, but the pressure buildup in storage is because if you add the liquid, cap, and store immediately,
the liquid will not be in equilibrium with its vapour in the container and so will vapourise over time until this equilibrium is reached. To fix this,
I recommend adding the liquid, loosely capping the container, shaking, venting etc (like a separatory funnel) until there is no sign of pressure
buildup (air has now been displaced by the vapour of the liquid). Adding the liquid while hot and doing this process would pull a vacuum which I
assume could be helpful for storing volatile materials. Note that this will not stop pressure buildup for materials that decompose into gases during
storage (e.g. HNO3).
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Sulaiman
International Hazard
Posts: 3734
Registered: 8-2-2015
Location: 3rd rock from the sun
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I have noticed three major sources of internal pressure
1) Decomposition
1.1 some compounds slowly decompose at RT (eg sodium hypochlorite solution)
1.2 higher temperatures, light etc can decompose compounds (eg nitric acid)
1.3 the worst (my opinion) are catalytic decompositions
(eg a tiny speck of something unknown in a bottle of hydrogen peroxide)
2) vapour pressure
All liquids and most solids have a vapour pressure, that increases with temperature.
Liquids boil when their vapour pressure exceeds local atmospheric pressure
So liquids become increasingly difficult to contain as their BP nears RT
Some liquids that boil below RT are prevented from boiling by pressure in the storage vessel
(eg liquid butane)
3) squeezing the plastic bottle too firmly
................................
I've still not found a way to open a cap insert without any possibility of a drop of liquid being expelled due to internal pressure,
Other than putting a cloth over when I open the cap and insert.
I'm not bothered by tiny droplets, or even a few drips/drops with most liquids,
but some liquids I don't want even one drop in/on/near me.
Does no one else have this problem ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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bnull
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Posts: 484
Registered: 15-1-2024
Location: South of the border, wherever the border is.
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Mood: Happy New Year!
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A simple way that will not work with everything is to stick a syringe needle, syringe attached, into the insert and let the vapor fill the syringe.
Then you remove the needle and open the insert. It must be one of those short needles, for insulin or penicillin, and a big syringe (50 mL).
If there was a way to make a tiny valve and glue it to the insert...
[Edited on 16-12-2024 by bnull]
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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