A solid substance can be corrosive

5. Protective measures for activities with irritating and corrosive substances

5.1 Technical protective measures

The measures listed below represent a selection. These are protective measures that experience has shown repeatedly to play a role in practice.

5.1.1 Work and storage rooms

Rooms in which irritating and corrosive gases, vapors or aerosols can occur must be well ventilated. Examples: Storage rooms for sodium hypochlorite, nitric acid and hydrochloric acid.

Floors should be resistant to the substances used and, for better cleaning, be tight, seamless and non-absorbent.

5.1.2 Filling, metering, pumping out

For filling and adding small quantities, e.g. B. from canisters, suitable devices are to be provided to avoid splashing or spilling. Such devices are, for example, hand pumps (Fig. 3) and metering taps.

Fig. 3: Hand pump for removal from canisters

Fig. 4: Dosing via suction lance

There is a lower risk of accidents if barrel pumps or suction lances (Fig. 4) are used for filling or metering. In automatic dosing stations, a chemical can be pumped from the container to the place of use in the desired amount or concentration in a largely closed system (Fig. 4 and 5). There are residual risks for employees when changing the container (e.g. risk of confusion) or when removing the suction lance (residual liquid is sprayed out of the lance).

Fig. 5: Splash protection (curtain) over flanges and pumps

5.1.3 Materials

Containers, pipes, hoses, sealing materials, etc. must be made of suitable materials. Inappropriately selected materials are attacked, a reduction in strength or leaks can result. The formation of an explosive atmosphere (generation of hydrogen when acids or alkalis act on light metals) or poisonous gases (e.g. formation of nitrous gases when nitric acid acts) is to be expected.

5.2 Organizational protective measures

5.2.1 Storage, keeping

Entering systems, work and storage rooms in which irritating and corrosive substances can occur in dangerous concentrations or quantities is only permitted for those employed there. Irritant and corrosive substances may only be present at workplaces in quantities that are necessary for the work to proceed. The containers are to be kept in one place and not scattered around the company.

5.2.2 Transport

Suitable transport aids such as safety containers, buckets with handles or barrel carts must be provided for transport.

Fig. 6: Safety container for manual transport

5.2.3 Dissolving, diluting

When dissolving and diluting many irritating and corrosive substances, e.g. B. from acids and bases, dissolving heat is released, which can lead to overheating and thus to splashing of the solution. By observing the following general rules, the heat released during the dissolving process can largely be dissipated:

  • Submitting the water ("First the water, then the acid, otherwise the monster happens" - the same applies to alkalis)
  • intensive mixing,
  • Quantity-controlled addition of the concentrate (adding solids such as caustic soda and caustic potash in portions),
  • Temperature monitoring.

5.2.4 Marking

Original container from the manufacturer

A not inconsiderable number of accidents with hazardous substances can be traced back to mix-ups. B. Adding concentrated alkali to acid or vice versa. Hazardous substances must therefore always be identifiable and adequately labeled (see Ordinance on Hazardous Substances). In the meantime, all transition periods for the introduction of GHS labeling have expired, so that only original containers with GHS labeling can be delivered. TRGS 201 regulates the classification and labeling of activities with hazardous substances.

In-house labeling of containers, storage tanks and pipelines

Clear and permanent labeling is also necessary for the internal use of irritating and corrosive substances. This is easiest for the company using it if the manufacturer's identification can be adopted, for example if the original container is used in the company.

Include in full labeling

  • Name of the substance or mixture,
  • Hazard pictogram (s) or the pictogram (s) (e.g. "exclamation mark" or "caustic hazard", possibly others),
  • Signal word ("Warning" or "Danger" - depending on the hazardous properties and concentration),
  • Hazard and safety information (H and P phrases),
  • possibly additional information.

In many cases, the risk assessment shows that full labeling is not necessary. A simplified labeling can then be made that contains at least the following information:

  • Name of the substance or mixture,
  • Pictogram (s) (e.g. "caustic hazard", "exclamation mark", ...),
  • further brief information if the information on the description of the hazard (s) is insufficiently meaningful.

Simplified labeling is regularly considered for storage tanks, pipelines and their connections, waste, containers for internal transport, laboratory bottles and suction lances. The marking can be attached to suction lances e.g. B. be attached to flags on the handle. In the case of very small containers such as small analysis vessels, an in-house sample designation is sufficient if identifiability is guaranteed.

A prerequisite for simplified markings is corresponding operating instructions as well as the instruction of the employees about the hazards occurring at the workplaces and the observance of the necessary protective measures.

Jobs

In addition, the safety and health protection signs in accordance with the technical rule for workplaces ASR A1.3 "Safety and health protection signs" must be affixed at workplaces: Safety signs, warning, mandatory, prohibition and information signs (e.g. mandatory signs for personal protective equipment in locations on which irritating and corrosive substances are handled openly).

5.2.5 Operating instructions

The operating instructions describe the necessary protective measures and rules of conduct that the employee must observe for his own protection and for the protection of other employees at the workplace (e.g. when preparing thinners, see Section 2.2).

The possible dangers associated with activities involving irritating and corrosive substances that have emerged from the risk assessment must be described in operating instructions.

Furthermore, the measures to be taken in the event of danger, operational malfunctions, accidents and emergencies (e.g. unusual pressure or temperature rise, leakage, fire, explosion) as well as in the context of first aid must be specified.

If many hazardous substances are used (e.g. in workshops), it is permissible not to create separate operating instructions for each individual hazardous substance, but rather to create group or collective operating instructions. The prerequisite is that activities involving these substances can result in similar hazards and that comparable protective measures are effective.

Operating instructions should, if possible, contain the pictograms of the original container.

Sample operating instructions can be found here.

5.2.6 Instruction

Using the operating instructions, employees (including external personnel) must be verbally instructed about any hazards that may arise and the corresponding protective measures. The instruction must be carried out on a job-related basis before commencement of employment and afterwards at least annually (every six months for minors). It must be in a form and language that the employees can understand. The content and time of the instruction must be recorded in writing and confirmed by the instructed person with a signature.

The documents for the briefing briefing on "cleaning agents" can be an aid for instruction in handling the often irritating and sometimes corrosive cleaning agents.

5.3 Personal protective measures

Whenever irritating or corrosive substances are handled "openly", personal protective equipment (PPE) must be used. This applies to direct activities such as B. filling (even smaller quantities), as well as staying or working in the danger area.

5.3.1 Eye and face protection

Eye protection is the most important personal protective measure when handling hazardous substances. In accidents with hazardous substances, the eyes are particularly often affected by chemical burns and the injuries that occur are often particularly serious.

Frame glasses with adequate side protection, possibly with corrective lenses for glasses wearers, are generally sufficient, for example. B. for monitoring activities in the factory and laboratory.

Suitable goggles are to be worn for all activities in which a risk to the eyes from splashing, irritating and corrosive liquids is to be expected, e.g. B. when filling liquids and eliminating malfunctions.

If irritating and corrosive gases, vapors or aerosols can occur, it is best to protect the eyes with a full face mask, e.g. B. with ABEK filter (multi-range filter) with protection against both organic and inorganic acids and alkalis.

If there is a greater risk of splashing - for example when adding larger amounts of caustic soda or caustic soda - a face mask (visor) may be necessary. The following applies here: depending on the posture in which you are working and where the chemical is located, it may also be necessary to wear protective goggles. Because it happens again and again that corrosive liquids splash under the visor into the eye area. If face protection is required, a chemical apron, boots and gloves must usually be worn (see following sections).

5.3.2 Hand protection

When working with irritating and corrosive substances, the hands can be protected by protective gloves made of durable plastic. Leather and cloth gloves are completely unsuitable.

No glove can be used universally, e.g. For example, the same glove that is used for activities with acids and alkalis may generally not be used for activities with organic solvents such as ethanol.

Many hazardous substances can penetrate the glove material, possibly at an astonishingly high speed. The protective gloves must therefore be selected in accordance with the manufacturer's resistance information and the intended use. Help on this can be found in the chemical manufacturer's safety data sheets and often on the glove manufacturer's websites. The technical rule for hazardous substances TRGS 401 "Risks due to skin contact - determination - assessment - measures" gives the basic procedure for selecting skin protection.

The following points, which repeatedly play a major role in operational practice, must be particularly observed:

  1. Wearing time: Protective gloves must not be worn longer than necessary, as frequent or prolonged wearing stresses the skin and can lead to skin diseases. Information on penetration times must also be observed.
  2. Latex: Due to the risk of allergies, avoid wearing protein-rich latex gloves (> 30 µg per gram of glove material). Powdered latex disposable gloves are prohibited.
  3. Damage: Protective gloves must be checked for damage before each use. Gloves that are damaged or otherwise unusable must be withdrawn from use immediately, disposed of safely and replaced with intact gloves.
  4. Carryover of hazardous substances: No hazardous substances may be distributed through used gloves (for example by touching light switches, doorknobs, telephone receivers, input keyboards or writing utensils).

5.3.3 Body protection

Depending on the extent of the hazard, aprons and boots must be worn in addition to eye and face protection. Aprons must be long enough so that no fabrics can get into the boots from above.

Before each re-use, body protection must be checked to ensure that it is in perfect condition, especially that it is flawless, in particular for material embrittlement.

5.3.4 Hygiene

The workplace and the work equipment must be kept clean, contamination must be removed immediately using suitable means. Food, luxury goods and pharmaceuticals must be stored in such a way that they do not come into contact with irritating or corrosive substances.

To protect against skin diseases when working with irritating and corrosive substances, protective gloves must be worn (see 5.3.2 Hand protection). In addition, a skin protection plan must be drawn up - in cooperation with the company doctor - that includes the use of skin protection, skin cleansing and skin care products.