A refrigerator or any other ignition sources such as power points and light switches must not be stored or installed in the chemical store if flammable or combustible liquids and solids are stored there. (AS 1940.2004; section 4.9.7)
Safety Data Sheets (SDSs) should always be referred to for safety precautions for handling and storing chemicals. Bromine water and iodine are both corrosive, toxic and belong to the same Australian Dangerous Goods (ADG) Code Class 8 and should be kept away from incompatible substances. Bromine water and iodine should be stored in their own tightly sealed containers within a secondary container, either in a corrosives cabinet or in the corrosives section of the chemical store, and segregated from any incompatible chemicals. Corrosive chemicals such as bromine water and iodine should not be stored in a refrigerator due to the lack of ventilation, and the ability of the vapours/fumes to corrode the metal components of the fridge. It is also important to check the lids periodically for cracks. Dilute iodine solution (iodine/potassium iodide) goes off very quickly, so it is best practice to prepare dilute iodine solutions as required.
Ammonia, amines, ethanal, alcohols (e.g. methanol, ethanol), butadiene, hydrocarbons, turpentine, acetone, hydrogen, combustible materials, sulfur, metals (e.g. aluminium, zinc, sodium, magnesium, lithium)
Ammonia (aqueous or anhydrous), hydrogen, aluminium, zinc, magnesium alkali metals (sodium, lithium), alkali oxides
Science ASSIST recommends the following.
- Flammable liquids should not be stored in domestic refrigerators and the refrigerator should be labeled with a prominent warning sign such as: “Not suitable for flammable chemicals”.
- Refrigerators should be located in the science preparation area away from the chemical store and flammable cabinet. Do not store chemicals and food together.
- Highly corrosive chemicals that produce vapours/fumes should not be stored in refrigerators due to the lack of ventilation and their ability to corrode metal.
- Chemicals stored in refrigerators should be in sealed containers and properly labeled with the contents, owner, date of acquisition or preparation and nature of any potential hazard. The labels used should be water resistant.
- Plastic trays can be used as secondary containment for all containers to capture spills and leaks.
- The condition of the refrigerator contents should be checked regularly for cracked caps and blurred labels.
- Both bromine water and iodine should be stored in their own tightly sealed containers within a secondary container either in a corrosives cabinet or in the corrosives section of the chemical store segregated from any incompatible chemicals. Quantities should be kept to a minimum.
- A bottle of dilute sodium thiosulfate (0.2M) should be kept nearby when handling bromine water or iodine. Spills of either halogen can be reduced to the halide (bromide, iodide) by addition of thiosulfate solution and disposed of down the sink with dilution.
- It is important that engineering controls, such as a fume cupboard, is used and that relevant PPE, such as gloves, safety glasses, lab coat and closed in shoes are worn when handling both bromine water and iodine.
Science ASSIST will be developing more specific guidelines for chemical storage in the coming months for chemicals included in our List of recommended chemicals for science in Australian schools.
Domestic refrigerators are commonly used in school science laboratories. These refrigerators provide an ignition source as they are not spark proof. Ignition sources must be excluded from identified hazardous areas such as the chemical store that may contain flammable and combustible liquids and solids. Domestic refrigerators are therefore not suitable for storage of flammable chemicals, or to be located in chemicals stores that contain flammable and combustible liquids and solids.
Domestic refrigerators have ignition sources within their electrical components such as:
- switches associated with the internal light and thermostat/temperature control;
- heating elements in frost-free fridges;
- an internal light;
- compressor motors and electric fan motors for air circulation; and
- power points.
Australian Standard 2243.2:2006 – Safety in Laboratories Part 2 Chemical Aspectsiii Section 4.4.3 part (c) states that,
A refrigerator may be used to store flammable chemicals provided it has been designed and manufactured to eliminate ignition sources. It may be possible for a domestic refrigerator to be modified by a competent person to eliminate ignition sources.
1 Refrigerators unsuitable for solvent storage should bear a prominent label inscribed with the words ‘Not suitable for flammable solvents’.
2 For a normal domestic refrigerator, removal of ignition sources entails removal of the wiring for the internal light, removal of the switching part of the thermostat from inside the compartment and possibly modification of any automatic defrosting procedure and internal fans, depending on the results of a competent person’s checks for their potential as ignition sources.
3 Solvents stored in suitable refrigerators should be properly labelled and sealed. A complete check of the condition of the refrigerator contents should be carried out at least monthly.
Spark-free laboratory fridges and freezers are available from scientific suppliers for the storage of flammable chemicals. See the Science ASSIST School science suppliers list.
Storing Bromine Water and Iodine
Improper storage of chemicals in schools can adversely affect the safety of students and staff as well as emergency responders. Any dangerous goods that are incompatible according to their Safety Data Sheet (SDSs) must be segregated from other incompatible substances by distance or containment barriers.
Bromine water is a clear orange liquid with a characteristic pungent odour. It is corrosive, emits toxic fumes when heated, is a powerful oxidiser and can cause severe eye damage and skin irritation. Best practice is to store bromine water in a tightly sealed glass container within a secondary container in a corrosives liquid cabinet, segregated from incompatible chemicals. Bromine water can be effectively stored on shelves in the general chemical store in the place designated for corrosives and segregated from incompatibles by containment barriers and distance. A corrosion resistant tray such as polypropylene can be used as a second containment or spill tray for the bromine water storage bottle.
The tray should then be kept on the lowest shelf possible and should not be above eye level. The cap of the container needs to be regularly checked as bromine vapours can degrade bottle caps over time.
Iodine is a volatile grayish black solid with a pungent odour that readily sublimes to violet vapours. It is corrosive and very toxic to the aquatic environment. It is harmful on contact with the skin and by inhalation. Iodine should be stored in a tightly closed corrosion resistant container within a secondary container on the shelf above the corrosive liquids and properly segregated from incompatibles.
Science ASSIST recommends a risk assessment be conducted prior to the use of any chemicals, and all appropriate control measures be identified and implemented. Science ASSIST has developed a one-page risk assessment template, see Risk Assessment Template.
Standards Australia. 2004. AS/NZS 1940 The Storage and Handling of Flammable and Combustible Liquids. Sydney. Australia
‘Chemical storage’ Question to Science ASSIST website. 17 February 2015 http://assist.asta.edu.au/question/2666/chemical-storage
Standards Australia. 2004. AS/NZS 2243 Safety in Laboratories, Part 10: 2004 Storage of chemicals. Sydney, Australia.
Standards Australia. 2006. AS/NZS 2243 Safety in Laboratories, Part 2: 2006 Chemical aspects. Sydney, Australia.
Baker Research Group. Safe Storage of chemicals Department of Materials Science and Engineering, Cornell University,, https://baker.mse.cornell.edu/ (Accessed October 2015)
i 'Iodine', Safety Data Sheet. September 2015. Chem-supply website, https://www.chemsupply.com.au/documents/IL0051CH37.pdf
ii ‘Bromine water’, Safety Data Sheet. July 2013. Chem-supply website, https://www.chemsupply.com.au/documents/AG0005_AU.pdf
Occupational Health and Safety Unit 2010. Guidelines for the storage of flammable solvents in refrigerators. The University of Queensland website https://ppl.app.uq.edu.au/content/2.70.07-storage-chemicals-fridges-free... (Link updated: 18 June 2018)
National Research Council (US) Committee on Prudent Practices in the Laboratory. 2011 Prudent Practices in the Laboratory; Handling and Management of Chemical Hazards. National Academies Press (US): Washington https://www.ncbi.nlm.nih.gov/books/NBK55868/
iii These extracts from AS/NZS 2243.2:2006 Safety in laboratories Part 2: Chemical Aspects are reproduced with permission from SAI Global Ltd under License 1407-c117.