Before working with chemicals you have to seek information about the substance's possible dangerous attributes. For instance, information about flammable, toxicity, etching, or long-term effects. Look at the label and the instruction manual. Please refer to the KIROS-database collection of workplace/supplier instruction manuals.
For substances or packaging materials with possible explosive attributes age, storage temperature, light influence and air influence can be final of the stability and it is particularly important that these substance are not purchased and stocked in larger quantities.
The Danish Emergency Management Agency has careful information about both peroxid formation and formic acid. Be careful already by transportation and opening of bottles if suspected of high peroxid content.
Peroxide formation classify in 3 groups (A, B and C). A simple way to inspect of peroxids in for instance ether is by mix a couple of ether mL with a potassiumiodide solution and a couple of drops attenuate hydrochloric acid and shake the mix. If the color turn brown it indicate a certain peroxid content.
The peroxid content can be controlled by peroxid strips (Merck 1.10081.0001, level 1-100 mg/l H2O2) and/or titanium(IV)oxysulfat-reagens (Fluka 34244). These methods often show different results. The recorded values will often be lower when measured with sticks than with titanoxysulphate method and too triacetoneperoxid is the difference high. Test should always makes before heating, concentration, and disposal.
Most peroxide formation chemicals is when delivery added inhibitors and chemical organisations guarantees normal a durability in unopened packaging of 3-5 years from production date. Too chemicals which is not added inhibitors is the durability shorter.
Some peroxide formation can cause explosive peroxide levels without concentration of the solvent and the general guideline to substitution involves for instance specific reasons to use diisopropylether.
If you suspect or find an actual high peroxide content (suggested limit at 100 ppm), contact your work environment leader for further steps. This can as among others be destruction of peroxides with a acidic solution of ferrosulphate.
Packaging with unstable chemicals have to be marked with label. At the label make a note of date of purchase and opening, stability control, placement and other things.
Suggestion to marking of labels of unstable substance:
Purchase / initials
Opening date / initials
Stability control test / initials
Locality / initials / department name
Pressure bottles with compress volatile is often used by all forms of laboratory work and cause more than one risk factor. Damaging of pressure bottles can cause explosions as a consequence of high pressure. A broken valve can cause heavy volatile leakage and the bottles behave as a projectile. The leakage volatile from a damaged bottle or a bad complete experiment can cause explosion and fire or poisoning, cauterisation or strangling after the volatiles nature. A overview over the normal used compress volatiles follows:
The pressure by 20 oC in trade vessels is stated.
150 -200 atm | 10 - 60 atm | 1 - 10 atm |
Hydrogen | Carbon dioxide (56 atm) | Ammoniac (8.5 atm) |
Oxygen | Chlor hydrogen (42 atm) | Chlor (6.5 atm) |
Nitrogen | Acetylen i acetone (20 atm) | Methylenchlorid (8.5 atm) |
Helium | Sulphur hydrogen (18 atm) | Sulphur dioxide (3.2 atm) |
Bortriflourid | Methylbromid (1.9 atm) | |
Ethyl | Fluoride hydrogen (1 atm) |
Work with and storage of floating nitrogen and carbonic acid ice (dry ice) involves risk of frostbite (N2, -196 oC ; CO2, -78 oC) and of nitrogen accidents (1 L floating carbonic acid will by 20 oC and 1 atm volume about ¾ m3). Carbon dioxide also has physiological effect and can in concentration of 10-20 % cause immediate dead. Floating carbon acid is often used in cold traps and can cause condensation of atmospheric oxygen in the trap as well as in the floating nitrogen in the dewar vessel. This oxygen can cause heavy explosions in presence of oxides substance. For instance organic connections. Therefore after use you have to take the coldtrap up from the dewar vessel and close the vacuum. The tap to the coldtrap has to remain open because these substances there for instance are condensed can get out.