It is important that lab work is carefully prepared, with regard to both safety and the end result. A continuously updated lab logbook is an invaluable and indispensable tool in this respect.
An evaluation of the risk and safety precautions is an important part of the preparation for your work. For example, it can be necessary seek information on the properties of a substance: State, reaction with water, combustibility (kindling temperature, explosion limit), caustic and corrosive properties, odour, toxic properties and especially long-term effects, penetration of rubber and plastic (gloves) its possible hygienic threshold.
For many known chemical reactions and products, much of this information is unavailable. Only typical physical and chemical properties are registered. However, various types of literature have articles describing substances that are hazardous to health and the environment.
When preparing for lab work (whether experimental or routine) each person must consider the risk involved.
- As a result of the physical, chemical and toxic properties of the chemicals, substances and compounds that are to be used or that can be formed.
- As a result of special characteristics (e.g. heat production) for the reaction or procedure that is being followed.
- As a result of the apparatus construction to be used.
- Search the literature for any missing information.
- Note down any relevant information in the laboratory logbook with regard to risks and precautions.
- Whenever alternative procedures are possible, then the least risky must be used.
- When a huge risk cannot be eliminated, consider dropping the experiment. If this is not possible, the project leader should carry it out or should watch over the procedure.
- The scientific staff member who starts up a project (project leader) must be acquainted with the health and environmental risks involved. Furthermore, the project leader is responsible for informing all persons (staff and students) involved of these risks so that they can take the necessary precautions before the project is started.
- Be prepared to give first aid to yourself and to others in the event of an accident or incident.
All work with substances and reactions that give rise to hazardous or malodorous gases or vapours must be carried out in a fume hood. As a general rule, the fume hood should be used for all forms of chemical work whenever possible.
The degree of safety provided by the fume hood depends partly on its technical and construction conditions and partly on personal and actual conditions, namely:
- The type and amount of the substance being used.
- How the user handles the substance and how the fume hood is being used.
- The set-up of apparatus or other kinds of hindrances to the flow of air inside the fume hood.
The temperature inside the fume hood.
The following rules apply to the use of fume hood:
- After opening the fume hood check that air is being extracted and that the alarm works. Be wary of a possible failure.
- Always have the least possible opening. It is not always possible to keep the fume hood completely closed when working in it.
- Respect the alarm. When it sounds, make sure to find out what is wrong.
- Keep your face (respiratory zone) over the lower edge of the fume hood window.
- Apparatus should be placed at the back of the fume hood and as far as possible from the side walls. Large apparatus that can interfere with the flow of air should be raised ca. 5 cm.
- Avoid rapid movements when working and when opening the fume hood. Make sure to button your lab coat. Do not have windows open and avoid moving quickly past these as this increases the risk of contamination.
- Keep to the general safety rules for working with inflammable material when working in the fume hood. An open flame must not be used.
- Keep the fume hood clean and tidy. Clear up and wipe the floor of the fume hood. It must not be used for storage of for example chemicals.
- In the event of any failure that is likely to be a safety risk, all work must be stopped immediately. Inform the management, the Occupational Health and Safety representative/supervisor or the departmental safety organisation about the incident.
- Equipment with heating must always be placed on a lift table so that heating can be turned off safely.
- Every three months, and own-check must be conducted of each fume hood and entered into the logbook or on form kept by the fume hood. The own-check includes control of the suction of the fume hood by putting a piece of paper on the edge of the fume hood, control of alarm with light and sound and clean-up.
Fume hood alarm:
The Danish Working Environment Authority (”Arbejdstilsynet”) demands that fume cupboards be fitted alarms that are activated when the airflow is inadequate.
Each fume cupboard has its own alarm, which sounds and shows a red light when the airflow falls below a certain level.
When a fume cupboard is closed there is still a slight suction. When the window is opened, the airflow is increased, but when the height of ca. 40 cm is reached, the alarm is activated. Even before this height is reached, air movement around the opening can reduce the effectiveness of the air flow, especially if more than one fume cupboard in a laboratory is open at the same time, as there is a limit to the total capacity for suction.