Sciencemadness Discussion Board

Storing chemicals and ordinary refridgerators and freezers

Mateo_swe - 1-7-2021 at 09:39

I have a bunch of chemicals that i know should be stored better.
When reading about storing chemicals many calls for lower temps and a lab refrigerator or lab freezer is recommended.
I as a hobbyist cannot get such a lab refrigerator or lab freezer, they cost a fortune, what should i do.
We are about to get new refrigerator and freezer for our kitchen and the old combo unit i might take into my lab area.
But do i dare store chemicals in this combo unit?
I read if not a lab freezer or lab refrigerator it should not be used, it can be dangerous.
Can a ordinary combo unit for food be made safe somehow?
Or is it better to store chemicals without the lower temps if a lab unit cant be found?

Jenks - 1-7-2021 at 11:01

I store some things in a regular refrigerator/freezer. Maybe the safety problem is with the possibility for explosion, if you were to store butane in your freezer for example. So don't do that, just store non-volatile stuff. Of course, co-mingling food with your chemicals is an additional level of hazard.

Some chemicals are stored at lower temperature to slow their reaction with atmospheric oxygen, moisture or carbon dioxide. Please let me suggest and strongly recommend that for such chemicals (such as aldehydes) that for long term storage you seal them in mylar bags with oxygen absorbers and/or desiccants as appropriate. All you have to do is buy empty bags and a bag sealer, which is basically a specialized iron that applies heat to the opening of the bag. Mylar plastic contains a film of metal that prevents small molecules from passing through. You will probably also find this useful for storing foods that degrade on exposure to air, and you will come to recognize and appreciate, as I do, the frequency with which such foods (such as chips) come packaged this way already.

RedDwarf - 1-7-2021 at 11:29

Most of us have some chemicals that could be stored better, temperature control, bunding, better separation etc etc. But like amateur fume hoods, it's a mistake to let best (professional) practice get in the way of better practice. One of the key reasons for people suggesting not using domestic appliances is because of mixing of food and chemicals, but there is also risk of incompatible materials (solvent or acid damage to a fridge or freezer that was only designed to hold milk and cucumbers) or as Jenks says, explosion risk with motors and switches that weren't designed for solvents. Unfortunately a lot of HSE regulations and best practice are designed so that people don't need to think about what they are doing. If you're only using the fridge/freezer for chemicals then you won't have that food contamination risk. as for corrosion or explosion you need to look at whether the risk of either will be increased compared with where you currently store the chemicals (your fridge motor won't be spark proofed, but I suspect that you already have similar spark risk in other areas of your lab such as light switches etc, so are you running a greater risk or not?). I would go with the repurposed domestic appliance (and I have a second hand fridge in my lab for what it's worth).

Fyndium - 1-7-2021 at 11:36

Where does this explosion risk arise, as chemicals are (supposed to be) stored in airtight containers that have leak rates of molecular level? I have 10 years old diethyl ether bottle that has lost negligible weight. If you wanna overproof it, get a big ziploc and put it in one.

macckone - 1-7-2021 at 21:27

Fire code says you can't store certain things in an ordinary refrigerator.
Some do with no consequences.
Occassionally, a lid isn't screwed on tight enough or a seal degrades, and there is an interesting news story.

Most modern refrigerator compressors are sealed, it is the thermostat and relay that could be a problem.
The other possible problem is the switch for the light, that can be easily remedied by simply disabling it as it isn't necessary. The next place for issues is if there is a fan that moves air between the freezer and refrigerator portion.
That is a major source of potential issues if it isn't a brushless motor, which most modern ones are.
The final possible issue is the ice maker if it has one. Best to just remove that or buy a fridge without one.

Modern refrigerators do away with mechanical relays and thermostats and use solid state.
The cheaper ones still use bimetallic strips.

SWIM - 1-7-2021 at 21:39

I thought lab freezers were ventilated in a limited way to avoid the buildup of explosive vapors.

If this is accurate, then it shouldn't be too hard to add some limited ventilation to a freezer unit. Like a small diaphragm pump on a timer.

If this isn't accurate it should still be easy to do, but maybe pointless.

Magpie had trouble with storing ether in his freezer (leakage ruined meat stored in there much to his wife's chagrin).

I forget the details, but since it was Magpie I assume he was using some pretty damn good containers.

Magpie was a serious and methodical fellow for the most part.

[Edited on 2-7-2021 by SWIM]

woelen - 1-7-2021 at 23:00

I would not store flammable volatile solvents in the refridgerator, but other stuff can perfectly be stored in a normal refridgerator. Most notable: H2O2, I2, Br2, SOCl2. Put I2, Br2 and SOCl2 in a secondary container with a little NaOH or Na2CO3 in it to absorb any fumes. Certain organics, which are not really stable, also benefit from storing in the cold.

It is the flammable volatiles, which are scary. In a normal cupboard, there always is ventilation, albeit only by diffusion. Even a small lab has 10 or more cubic meters of air and there also is at least some ventilation. Your seals must be really bad, before you build up dangerous concentrations of flammable fumes. Inside a small fridge of 0.2 cubic meter volume, there can be a much stronger buildup of fumes.

unionised - 2-7-2021 at 00:02

Lab fridges and freezers are modified by moving the switching part of the thermostat outside the chamber in which you store stuff. This separates the spark from any flammable vapours.

I know of a lab where the fridge used to store the urine samples exploded- the door of the fridge took a chunk out of the wall opposite.
If anyone had been in the way they would probably have been killed.

That fridge wasn't spark proof because it was only used for urine samples.
But one day someone got a bunch of samples in a well-plate, extracted them with ether, covered the well plate with essentially clingfilm, and then returned it to the fridge.

It's only luck that nobody was hurt.

Our lab now has a policy that we only buy spark proof fridges.

In principle, there's nothing to stop someone making the same modification to a domestic fridge- moving the electrical contacts outside the enclosed , cold bit.

Mateo_swe - 2-7-2021 at 06:20

I would not trust the old refridgerator/freezer combo i will get to use to be spark free.
Even many new items use old non-brushless motors because its cheap.
The sealed mylar bags are a good idea, very good actually, i try that.
Storing some solvents in ziplock bags seems to do nothing, the smell goes right through and that means the vapours do too.
I think i will use the old refridgerator/freezer for all things except flamable stuff, solvents and strong acids.
But i think there are some UV-light inside i need to disconnect.

It seems the chemicals that really could use good storage is the hardest to store properly, like ether, flamable solvents and corrosive acids.
I have a 2.5L diethyl ether flask that currently is stored in a plastic pail on the floor in a cold but dry part of the house.
The pail maybe sounds like a bad idea as heavy fumes can build up but i think its good as i can put my nose in and sniff for fumes that have leaked.
And as long as i cant smell any strong fumes i guess its alright.
Its unopened and i cant smell any ether smell from it, not any stong smell atleast.
I have other stuff stored that do smell a little so its hard to differentiate what smell is what.

I think i will store most volatile solvents just on shelves and put a small sparkfree fan connected to a pipe that goes to the floor and the other end outside.
Then i can use a timer to run it 15-30 minutes a few times per day to fan out any smells and vapours.
Small fans for boat engine rooms are spark free and avaliable.

Fyndium - 2-7-2021 at 22:08

I must ask, what type of containers you keep your stuff? As I have never had issues with escaping, evaporating or smelling reagents when I have used actual reagent bottles? The canisters my ether from Sigma are from, are made out of aluminum and the cap is very thick and sturdy. Only instance I've gotten toluene evaporated were storing it for years in the original commercial packaging which had a flip-up spout made from thin LDPE, which the toluene diffused through like nothing. Most of the 1L can were gone when I found it from the bottom of a shelf.

Ziploc bags block pretty much zero odors or volatile vapors, but they allow for easier observation of possible leaks. They also offer secondary protection against leaking or broken contents.

Mateo_swe - 4-7-2021 at 04:19

The things that smell are,
Some solvent mix "cellulose thinner" in a original metal container with a plastic outlet on top, this one smell and i have them in a ziplock bags that doesnt seem to stop any smell.
A plastic box where i got 2pcs 5L pails of DCM and some 4pcs of 500ml plastic bottles of 38% Formaldehyde, this smell much, probably the Formaldehyde.
The Formaldehyde plastic bottles seem not good quality bottles, i must put it in decent reagent bottles, i have such empty glass bottles with blue lids.
I have a HCL bottle that might smell a little and i think it makes stuff rust nearby.

I seem to remember my glacial acetic acid in a original i think HDPE plasic bottle, did smell but when checking on it now i cant smell anything.
2,5L dietyl ether in a unopened glass reagent bottle seem not smell anything either.
Some other chemicals that are in original glass bottles dont smell (pyridine, Acyl chloride, Toulene, Propionic acid and others).
Also i have HDPE (i think) bottles of acetic anhydride, THF, acetonitrile, some acids but that doesnt seem to smell either.

If i put everything in reagent bottles (the type with blue lids) it shouldn't smell, right?
I will try find mylar bags and a sealer, this can be useful to have for other things too.

MidLifeChemist - 4-7-2021 at 13:26

I store my iodine and H2O2 in our 2nd refrigerator that is in the garage. If I make bromine, I'll probably store that there too, or in the freezer. I like the idea of storing iodine and bromine inside a 2nd container with some base in it, thanks for that idea Woelen.

Mateo_swe - 12-7-2021 at 14:51

How long can one store H2O2 before the % starts to go down?
I have heard people say "my H2O2 is old, probably only water by now" and i also heard that the % doesnt go down with storage-time/age as quickly as many thinks.
Also how much better is it to store H2O2 in a refrigerator vs dry roomtemp, big difference?

Herr Haber - 15-7-2021 at 08:50

Quote: Originally posted by Mateo_swe  
How long can one store H2O2 before the % starts to go down?
I have heard people say "my H2O2 is old, probably only water by now" and i also heard that the % doesnt go down with storage-time/age as quickly as many thinks.
Also how much better is it to store H2O2 in a refrigerator vs dry roomtemp, big difference?

UN HDPE bottle stored under the sink swelled quite a bit
Glass bottle in veggies compartment doesnt seem to outgas anything.

Correction to that last statement: just checked on the bottle after 1.5 years and there was indeed pressure.

Mush - 5-8-2021 at 15:17

Quote: Originally posted by Mateo_swe  
How long can one store H2O2 before the % starts to go down?
I have heard people say "my H2O2 is old, probably only water by now" and i also heard that the % doesnt go down with storage-time/age as quickly as many thinks.
Also how much better is it to store H2O2 in a refrigerator vs dry roomtemp, big difference?

Hydrogen Peroxide Shelf Life

"A 3% hydrogen peroxide solution stored at room temperature under normal conditions can be expected to decay at a rate of 0.5% per year.(1)"

Factory sealed, in original bottle (preferably black), kept away from heat
and uv source perfectly fine for years. Stored in a proper way, cc h2o2 (30%) will be fine for 5+ years or even much much longer.

"Research indicates a sealed bottle of 4% hydrogen peroxide decomposes from 4.2% to 3.87% within three years, while a 7.5% solution degrades from 7.57% to 7.23% in three years."

[Edited on 5-8-2021 by Mush]

HydrogenSulphate - 5-8-2021 at 16:08

I have my ethylenediamine, supposedly of 99% conc, stored in a second hand repurposed chest freezer. I transferred the reagent to a tightly-stoppered PTFE-lined Simax reagent/media bottle, after I noticed that the cap of its original bottle had signs of deformation. I've encapsulated the Simax bottle in several layers of clingfilm, to cushion the brittle glass against knocks and shocks. Literature value of its MP is 8-10 degrees C. Strangely, it is remaining as a liquid at the subzero temperatures of the freezer. My ethylenediamine hardly fumes in humid air, either.

[Edited on 6-8-2021 by HydrogenSulphate]

karlosĀ³ - 5-8-2021 at 16:12

I had a friend who lately also had a fridge-related incident which burned half his lab down.
Luckily it was appropriately insured :o

But it was not spark-related as far I know(there was a fire investigator and all), I just know that the cooling fluid somehow was at fault, butane I think(isn't this common nowadays?).
I don't know what truly caused it.

Just tell this because it illustrates that a fridge doesn't neccessarily makes storage safer by itself.
I don't think it was a special fridge for chemicals, but I guess, the insurance company wouldn't have paid otherwise, no?
Or if it even was used to store chemicals, and not just to cool reaction mixtures down etc.

macckone - 5-8-2021 at 21:15

Yes there are butane refrigerators.
If they leak they are a fire hazard.

Regardless of rather the refrigerator was rated for flammables, if it was a coolant leak then it was not a storage issue.

Insurance can generally only refuse to cover a loss if the fire was a result of something the policy holder did.
ie. storing gasoline next to a water heater
And must cover damage due to rated appliances.
ie. water heater blows up

This is a good example of that type of difference.
Explosion due to refrigerant leak not what was stored in the refrigerator.

On a side note all hydrocarbon refrigerators are required to be explosion resistant.

karlosĀ³ - 6-8-2021 at 09:28

I'll get some more details, its all quite fuzzy from what he told me, and then I'll see if it is useful for this thread.

Explosion proof, hmmm, I in that case the stored insides could have gotten off well, but I don't remember this either.

I mean, fridges don't cause a fire regularly, thats rather rare, and I would think the fact that it was in a labspace must coincide with this somehow.
But I could be wrong, as said I try to find out more and will not comment more from my fuzzy memories of that occurence until then.

macckone - 6-8-2021 at 13:46

R600A is isobutane.
Those models only have less than 3 ounces but the UL requirements are non-sparking switches and motors.
So any model with R600A has to be explosion resistant to some extent.

There were a lot of problems with the whirlpool models due to a defect in soldering the system.
Lots of explosions and fires.

I am sure some other brands have had problems as well but probably not as consistent.