In brief
Acids and bases are different chemicals, but at work they produce the same result: a chemical burn that starts within seconds and deepens unless it is washed with water for a long time. Most accidents happen during dilution, transfer from one container to another and clean-up of spills. The measures come in three parts: the right method (acid is added to water), an accessible eyewash and emergency shower, and eye, hand and body protection chosen according to the information in the SDS.
Working with corrosive chemicals: why do acids and bases carry the same risk?
Adding sulphuric acid to a plating bath, preparing caustic soda solution in a dye house, filling a clean-in-place (CIP) line in a food plant or adjusting pH in water treatment all involve the same hazard: a chemical burn to the skin, eyes and airways. In textile finishing, metal plating, chemical and food plants in Bursa and the surrounding provinces, working with corrosive chemicals is part of the daily routine; and because it is routine, the risk is underestimated.
On the label and safety data sheet (SDS), these substances are recognised by the same warnings: the corrosion pictogram (GHS05) and the statements "causes severe skin burns and eye damage" (H314), "causes serious eye damage" (H318) or "may be corrosive to metals" (H290). For how to read a label, see our article on chemical labels and hazard pictograms; for the sections of the SDS, see how to read an SDS.
There is an important difference between acid and alkali burns: acids coagulate tissue where they make contact, which to some extent limits their own progress; bases (alkalis), on the other hand, penetrate deeper by dissolving tissue. That is why a caustic soda splash in the eye, even if it hurts less at first, is generally more dangerous in terms of permanent loss of sight. In both cases the first and most important step of treatment is the same: wash with plenty of water for a long time, without any delay.
Caustic soda hazards and the different faces of acids
Belonging to the same class does not mean they behave the same way. The specific hazards of the corrosives most often used at work are as follows:
| Chemical | Typical use | Notable additional hazard |
|---|---|---|
| Sulphuric acid | Plating, batteries, pH adjustment | Releases a lot of heat when mixed with water; the concentrated form burns by drawing water out of tissue |
| Hydrochloric acid (muriatic acid) | Metal cleaning, pickling | Vapour irritates the eyes and airways; corrodes metal shelving and containers |
| Nitric acid | Passivation, etching | A strong oxidiser; can start a fire with organic material such as swarf, rags and wood |
| Hydrofluoric acid | Etching glass and stainless steel, some wheel cleaners | Pain may be delayed; penetrates deep into tissue and binds calcium in the body; keep the specific first aid given in the SDS (usually calcium gluconate gel) ready |
| Sodium hydroxide (caustic soda) | Dye house, CIP cleaning, degreasing | Heats up and spatters as it dissolves in water; spilt solution makes floors slippery; permanent eye damage |
| Sodium hypochlorite (bleach) | Disinfection | Releases chlorine gas when mixed with acid |
These differences directly affect storage, transfer and emergency response decisions. List all the corrosives on your site in a chemical inventory and transfer sections 7 (handling and storage) and 8 (exposure controls and PPE) of the SDS for each one into the work instruction.
The acid dilution rule and safe transfer
The acid dilution rule is a single sentence: add acid to water, never water to acid. When water is poured onto concentrated acid, the first drops heat up suddenly at the surface and boil, spraying acid around. When acid is added slowly to water, the heat released is spread through the large volume of water. The same logic applies to solid caustic soda: flakes or granules are added to cold water in small portions while stirring; they are not dissolved in hot water or by pouring water on top of them.
The written instruction for dilution and preparing solutions should include these steps:
- The work is done under local extraction or in a well-ventilated area; for fuming acids, local exhaust ventilation must be running.
- The container is made of heat- and chemical-resistant material, and the required amount of water is put in first.
- The acid or solid base is added slowly while stirring; the rate of addition is adjusted to how hot the container gets.
- It is checked in advance that the route to the eyewash and emergency shower is clear and that they work.
- The container of the prepared solution is labelled immediately with its contents and concentration.
The most common dangerous habits during transfer are: tipping a drum to pour into a bucket, siphoning with a hose by sucking by mouth, decanting small amounts into unlabelled plastic bottles, and trying to empty a drum with compressed air. Instead, use a drum pump suitable for the chemical, a drip tray under the IBC valve, and labelled, compatible secondary containers.
Storage and acid spills
Art. 7 of the Regulation on Health and Safety Measures in Work with Chemical Agents requires that, in the processing, storage and transport of chemicals, contact between chemical agents that may react with each other is prevented. For corrosives, this means in practice:
- Acids and bases are kept in separate cabinets or separate spill bunds.
- Oxidising acids such as nitric acid are kept apart from organic substances, solvents and other acids.
- Hypochlorite is stored away from acids.
- Containers stand below eye level, so they cannot tip over, on spill trays.
- Shelving is made of corrosion-resistant material; metal shelving rusted by acid vapour is inspected regularly.
For a detailed incompatibility table, see our article on compatible chemical storage.
In an acid spill or base spill, the first thing to do is clear the area and stop the spilt chemical from reaching drains and other chemicals. Clean-up is done only by a trained person wearing suitable PPE, using an absorbent suitable for the chemical. Neutralisation is applied only if the SDS recommends it, taking into account that heat will be released; randomly pouring a base onto acid causes a second splash. The steps of spill response are in our article on responding to chemical spills.
The eyewash and emergency shower requirement
Turkish legislation sets no numerical criteria for eyewashes and emergency showers. However, Art. 7 of the Chemical Agents Regulation requires suitable and adequate facilities for workers' personal hygiene, and Art. 8 requires preparedness for emergencies arising from hazardous chemicals. Where corrosive chemicals are handled, the practical form of this preparedness is an eyewash and an emergency shower. The source most widely referred to for how to install them is the US standard ANSI/ISEA Z358.1; in Europe, the EN 15154 series covers the same subject.
| Criterion | Approach in ANSI/ISEA Z358.1 | Check on site |
|---|---|---|
| Travel time | Reachable from the hazard within 10 seconds at most | Is the route on the same floor, unobstructed and free of doors? |
| Flushing time | At least 15 minutes of continuous flow | Is it plumbed in, or if self-contained, is the capacity sufficient? |
| Water temperature | Tepid: 16–38 °C | Is there a risk of freezing in winter or heating in the sun in summer? |
| Testing | Weekly activation for plumbed units | Is a weekly activation record kept? |
The right PPE for acid handling safety
PPE comes after engineering controls, but it is indispensable when working with corrosives. It is chosen according to section 8 of the SDS and the type of work:
- Eyes and face: closed goggles marked "3" (liquid droplets and splashes) under TS EN 166. For tasks with a high splash risk, such as pouring, diluting and opening drums, a face shield is worn over the goggles. For details, see safety goggles and face shields.
- Hands: chemical gloves conforming to TS EN ISO 374-1. The material (nitrile, neoprene, butyl, PVC) is chosen according to the chemical and its concentration, based on the manufacturer's breakthrough time table. See choosing work gloves.
- Body: a chemical-resistant apron for small splashes; for tasks with a risk of heavy splashing or spraying, liquid-tight (Type 3) or spray-tight (Type 4) protective clothing; boots, with trouser legs worn over the boots.
- Respiratory: where there is hydrochloric or nitric acid vapour or acid mist, a mask with a suitable gas filter if ventilation is not sufficient. For filter types, see our article on gas mask filters.
Taking PPE off is at least as important as putting it on. Touching the face, a phone or a door handle with contaminated gloves carries the chemical to unprotected areas. At the end of work, the gloves are first rinsed with water while still being worn, then the apron and face shield are removed, the gloves last, and hands are washed. Workwear splashed with chemicals is taken off immediately and not taken home; it is replaced with clothing that the employer has cleaned.
The order in which measures are chosen is the subject of a chemical risk assessment; for the method, see our article on how to carry out a chemical risk assessment, and for sector-specific risks, see our chemicals and plastics sector page. We address work with corrosive chemicals at your site under our risk assessment service, planning points that require measurement with authorised laboratories.
Frequently Asked Questions
Why is water not added to acid when diluting?
The first drops of water added to concentrated acid boil from the sudden heat and spray the acid. When acid is added slowly, while stirring, to water already in the container, the heat is spread through the large volume of water. Solid caustic soda is likewise added to cold water a little at a time.
What should I do first if caustic soda splashes into my eye?
Go to the eyewash immediately and rinse for at least 15 minutes, holding your eyelids open; meanwhile someone else should call 112. Because bases penetrate deep into tissue, do not stop rinsing even if the pain eases, and do not return to work until your eye has been examined.
Is an eyewash mandatory in every workplace?
There is no numerical eyewash provision in the legislation; the need is determined by the risk assessment. At points where corrosive chemicals are handled, diluted and transferred, an eyewash and, where necessary, an emergency shower are a basic part of preparedness for chemical emergencies.
Can we neutralise an acid spill by pouring a base on it?
Only if the SDS recommends it and a trained person does it wearing suitable PPE. Random neutralisation releases heat and causes splashing. First clear the area, stop the spread and use an absorbent suitable for the chemical.
A risk assessment that identifies and scores hazards on site, links each measure to an owner and a date, and has a clear renewal schedule.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.