AS 2243.2:2021 – Safety in laboratories Part 2: Chemical aspects and storage.
Section 4 Safe use of chemical substances
4.1 General
Laboratories are unique in that they have a diverse range of chemicals. often in smaller quantities than in industrial environments. The methods and systems used within the laboratory can be complex. Hazardous situations can arise in day-to-day operations if personnel are not appropriately trained and aware of the hazards.
This sectwn provides guidance on the range of common chemical hazards that can be encountered in laboratory operations and the precautions to be adopted to address the hazards.
NOTE Appendix K lists the ADG categories versus the GHS categories.
4.2 Chemical hazards
Chemicals can be hazardous due to their physical properties, chemical nature or interaction with living organisms.
The storage conditions of the chemical substance can also present a hazard if the storage containers used are incompatible with the substance (e.g. storage of peroxides in metal containers) or if the substance is stored under poor environmental conditions (e.g. hot conditions, or those which can lead to the deterioration of the storage container).
Consideration should be given to substituting a less hazardous material for use, where possible.
Chemical safety is subject to national, state and territory legislation. Some specific chemicals, due to their public health impact, are legislated under drugs, poisons and controlled substances legislation and related legislation for agricultural and veterinary chemicals.
NOTE I For an explanation of dangerous goods classes, consult the AVG Code.
NOTE 2 In New Zealand, consult NZS 5433 and hazardous substances regulations.
4.3 Gases
4.3.1 General
All compressed and liquefied gases should be regarded as hazardous. Hazards arise from one or more of the following factors:
(a) compressed state — Rapid expansion takes place suddenly and with considerable force on release of the gases from their container, e.g. compressed nitrogen.
(b) Low temperature — Many gases, when released rapidly, become cold as a result of adiabatic expansion. Also, gases stored as cryogenic fluids are at exceptionally low temperatures upon release (refer to AS 1894 for further information).
(c) Reactivity — Gases (e.g. chlorine, oxygen, nitrous oxide) that are normally highly reactive with certain substances tend to be even more so when released from a compressed state by virtue of their high concentration.
(d) Flammability — Many compressed gases are flammable and should be treated as such. A high concentration combined with pressure increases the risk of a potential hazard.
(e) Toxicity — The toxic properties of gases, such as ammonia and chlorine, increase with higher concentrations.
(f) Oxygen depletion — Gas released may displace air, which can cause asphyxiation even though the gas may not be very toxic. Examples of these gases include carbon dioxide, helium and nitrogen.
(g) Density effects — Gases that are heavier than air, such as LP Gas and carbon dioxide, can travel large distances without dilution (or dissipation).
Depending on their nature, gases used in laboratories are usually contained in one of three ways, each presenting its own specific hazards, as follows:
(i) High pressure cylinders at approximately 13.7 MPa or at 30.0 MPa. Examples are oxygen, nitrogen, hydrogen, and methane.
(ii) Liquefied or dissolved gases in cylinders under pressure. Examples are LP Gas, propane, ethylene, acetylene, chlorine, ammonia, and sulfur dioxide.
(iii) Refrigerated liquid gases in vacuum jacketed containers at pressures between 100 kPa (approximately one atmosphere) and 20 MPa. Examples are refrigerated argon, helium, liquid air, carbon dioxide, oxygen, nitrogen, hydrogen, and neon.
Cyhndcrs shall be handled and stored in accordance with AS 4332 and AS/NZS 2243.6.
4.3.2 Handling of gases, compressed or liquefied (other than cryogenic liquids)
In addition to the mechanical aspects covered in AS 4332 and AS/NZS 2243.6, the following chemical precautions shall be taken when handling compressed or liquefied gases other than cryogenic liquids:
(a) Materials that a gas comes in contact with prior to its use shall be chemically compatible with that gas.
(b) Cylinders or gas lines used for flammable gas shall be earthed.
(c) When leak-testing or cleaning an oxygen system only solutions that are compatible with oxygen shall be used.
(d) If the gas is corrosive or toxic, adequate precautions shall be taken before it is used, and emergency equipment shall be readily available, e.g. respirator, breathing apparatus, resuscitator and antidote.
e) The venting of gases or lines shall bc carried out. For Class 2.1 flammable gases In cylinders, the cylinder shall be held vertically in a well-ventilated area. LP Gas shall not be released where a potential ignition hazard exists or where a hydrocarbon cloud can he formed in low- lying areas (refer to AS/NZS 1596). Where flammable gases that are lighter than air are used or stored in cylinders, high level ventilation shall be provided to prevent accumulation of a flammable concentration of gas.