Safe working practices

The storage of a working stock in the workplace is permitted, but not in large quantities. Regulations (PGS 15) stipulate a maximum of 25 kg or litres of dangerous substances per room. For flammable liquids under processing or as waste, the limit is set at 1 litre per m2 floor area. If this quantity is exceeded, storage in a ventilated safety cabinet is required. Always use as small a volume as possible for the working stock.

 

No, spraying creates a fine mist and a the alcohol will evaporate rapidly. This can lead to the limit (maximum concentration of a substance in the individual breathing zone of a worker) being exceeded. In that case, there is a risk of harmful health effects or of the lower explosion limit being exceeded. Spreading the alcohol over the worktop with a damp cloth reduces this risk. Also, always be alert to sources of ignition when using alcohol.

Watch the video about spraying alcohol in the Good practices section.

A room once exploded due to spraying alcohol while the gas burner was still on. Spraying other substances may also lead to high concentrations in the ambient air. Spraying is therefore advised against wherever possible.

Yes, but only if you place them in a fire protection cabinet. A fire protection cabinet has a fire retardant effect and is therefore suitable for storing flammable substances.

 

Yes, but after cleaning with one product, you should rinse with plenty of water before cleaning with the other.

You can also do it the other way around: first with chlorine and then with a powerful cleaner. But again, rinse with plenty of water before applying the other product.

No, it is not a good idea to mix cleaning products. Business processes use concentrated and powerful products of which not all components are always known. Mixing different products can lead to highly undesirable reactions.

The material safety data sheet (MSDS) of a product provides information about personal protective equipment. If it is unclear which means of protection you should use, please contact your OHS service. This information can also be found in the local registration system for dangerous substances and the linked NFU dangerous substances database. You are also obliged to wear personal protective equipment if this is prescribed because of the risks.

Yes, acids and lyes must be placed separately in drip trays only for stock storage. It is advisable to place unstable volumetric flasks in a receptacle to prevent them from falling over and leaking.

 

Yes, fume cupboards usually have an indicator light showing whether the fume extractor is working. Therefore, make sure that a broken laboratory fume cupboard light is replaced immediately.

Sometimes cabinets are fitted with an underpressure gauge. A small banner placed at the rear flow partition or a tissue at the window opening can indicate whether the cupboard is still working.

If the cupboard is overfilled (e.g. with waste containers), this can have a significant effect on its operation. You can check whether the cabinet still works properly by means of airflow measurements in the window opening in various places or by means of smoke tests. If serious doubts remain as to the proper functioning of the system, a professional measurement can provide the answer.

Yes, a PME (preventive medical examination) is normally offered to you when you first start working with dangerous substances and if the risk assessment has shown that you will also be exposed to these health damaging substances (such as analysts who work with TB cultures). You can also apply for a PME if you or your colleague have a condition that could be the result of working with dangerous substances.

 

No, in the case of dangerous substances, this is not always the case.

There are some criteria for carrying out a health examination. This means that it is sometimes not useful to have one carried out, for example in the event of:

Specificity
A medical examination that is specific to the risk in question and has a predictive value must be available.

Relevance

The results of the research must be relevant and lead to consequences.

Alternatives

If there are other or better means of achieving the same objective, these should be used.

Proportionality

The material and immaterial costs for the employee and the company must be in reasonable proportion to the intended purpose.

No, in principle is not. In laboratories, the air management is set so that air in the room is changed several times per hour. The pressure in the laboratory is lower than that in the corridor. If the door remains open, the underpressure disappears and vapours and smells spread from the lab to the surrounding corridors.

Short-circuiting of air flows also affects the ventilation of the laboratory space. Doors also form part of the fire resistance of a room and must therefore remain closed. It is forbidden to leave the doors of radionuclide and GMO laboratories open.

Yes, but only in part. The statutory limit and the administrative limit of a solvent indicate which concentration is still permitted or accepted. A substance with a low limit, such as chloroform (5 mg/m3 ), is more hazardous than ethanol (1000 mg/m3).

Whether or not the limit is reached during work depends very much on the degree of evaporation of the solvent. In addition to the type of action, the vapour pressure (P) is a determining factor. Working with ether (with a P of 587 mbar) will cause the limit (308 mg/m3) to be exceeded much more readily than working with xylene with a P of 8 mbar, although this has a lower limit (210 mg/m3).

The P/limit ratio, the relative inhalation risk, is a good parameter for comparing the risks of solvents. It is important to realise that the largest concentrations of solvent are generated in the air, especially when pouring solvents into another receptacle. Please note that the limit does not take fire risk into account.

The abbreviation MAC value is no longer used; the term limit has been introduced for this.

No, residues of chloroform, phenol or alcohol, for example, are often placed in a fume cupboard to evaporate. However, dangerous substances must be disposed of as such.

Discharges or emissions into the environment should be avoided as much as possible. Deliberately evaporating or flushing solvents if there are alternative disposal options is therefore not permitted.

Yes, if you abide by the following rules:

• Do not carry large amounts of liquid nitrogen in a lift with people in it.
  As a general rule, quantities of less than 1 litre are permitted.
• Transport the container in a stable condition.
• Transport a large amount of nitrogen with 2 people: the first person operates the lift externally with a key switch and the second person waits for the lift with the nitrogen container to arrive on the destination floor. People are not allowed in the lift.