Fire in Paint and Varnish Manufacturing Plants

Paint factory safety: the risk changes throughout the process

In a plant producing paint, varnish and thinner, fire risk is not concentrated at a single point. Large volumes of flammable liquids in the raw material store, dust in the weighing area, vapour and heat during mixing and dispersion, static electricity during filling, and solvent-soaked rags during cleaning all stand out. Paint factory safety therefore starts with a process map. This article focuses on the manufacturing plant; we cover the spray booths where paint is applied separately in our article on spray booths and painter risks.

Stage	Fire and explosion risk	Exposure risk	Key measure
Raw material receipt and storage	Leaks and vapour from solvent tanks, drums and IBCs	Vapour during transfer	Earthing, spill bund, ventilation
Weighing and bag emptying	Pigment and filler dust cloud	Respirable dust	Bag emptying station with dust extraction
Premixing and dispersion	Vapour at the tank opening, frictional heat	Solvent vapour	Lidded tank, local exhaust, temperature monitoring
Let-down and tinting	Vapour from open containers	Solvents and additives	Closed transfer, small-container discipline
Filtration and filling	Static electricity, spills	Vapour, skin contact	Equipotential bonding, dip pipe, low initial flow rate
Tank and equipment washing	Dirty solvent, confined space	Heavy vapour	Work permit, ventilation, recovery
Waste and dirty rags	Self-heating	—	Lidded metal waste bin

Two regulations provide the legal framework for this table. Art. 5 of the Regulation on the Protection of Workers from the Hazards of Explosive Atmospheres requires measures in this order: first prevent an explosive atmosphere from forming, if that is not possible prevent ignition, and if that too is not possible reduce the harmful effects of an explosion. Art. 7 of the Regulation on Health and Safety Measures in Work with Chemical Agents repeats the same priority for fire and explosion measures and requires equipment of a suitable category to be used in explosive atmospheres.

Solvent vapour in the mixing tank

The mixing tank is where solvent vapour is most concentrated. In an open tank with the mixer turning, the liquid surface is constantly renewed and evaporation speeds up. Points to watch:

Vapour collects low down. The vapour of most solvents used in paint manufacturing is heavier than air; it collects at floor level, in channels, pits and under tanks. Place extraction points not only at the ceiling but also at the low points where vapour collects.
Compare the flash point with the process temperature. The flash point in section 9 of the safety data sheet shows the temperature at which the liquid starts to form a flammable vapour. If the process temperature approaches this value, the atmosphere inside the tank and around its opening should be treated as flammable.
Dispersion generates heat. High-speed dispersers and mills heat the product through friction. Check that the cooling jacket is working and that product temperature is monitored; if the temperature rises, evaporation also increases.
Lid and extraction. Keep the tank opening as closed as possible during mixing; at points that must stay open, use local exhaust close to the opening. In some plants, the atmosphere inside the tank is protected with an inert gas such as nitrogen; this decision requires an engineering assessment.

The inside of the tank and the area around its opening are usually classified in the explosion protection document as the highest-risk zones. We explain zone classification and the equipment categories that can be used in each zone in our article on ATEX and the explosion protection document. Equipment such as mixer motors, lighting, torches and radios must be suitable for the zone.

Pigment dust and bag emptying

Pigment dust creates two separate problems. Organic pigments and some fillers are combustible dusts; the dust cloud formed when emptying bags can explode with a suitable ignition source. The same dust is an exposure risk when inhaled; some inorganic pigments may contain heavy metal compounds. Sections 2, 3 and 8 of the product's safety data sheet show which of these applies.

The most critical moment is when powder is emptied into a solvent tank. At that point, a combustible dust cloud and solvent vapour are present at the same time; static charge generated by a plastic bag sliding or rubbing can ignite this mixture. Measures:

Empty bags at a station with dust extraction or with local exhaust close to the tank opening.
Earth the tank, platform and emptying hopper; give the operator antistatic footwear and workwear.
Empty the bag slowly and in a controlled way; do not shake out the empty bag over the tank.
Review the order of the recipe from the point of view of this risk; aim to have as little free vapour as possible at the tank opening at the stage when powder is added, and do not heat the tank at that time.
Clean up spills with a suitable industrial vacuum, not compressed air.

If workplace air measurement is required for dust exposure, we plan measurements with authorised laboratories; we enter the results into the risk assessment and set up health surveillance together with the workplace physician.

Static electricity in paint filling

The paint filling static risk comes from the electrical charge generated as liquid is transferred through pipes and falls into a container. Low-conductivity solvents in particular build up this charge easily. Apply the following rules on the filling line:

Equipotential bonding: the tank, pump, pipework, filling nozzle and the metal container being filled are connected to the same earthing system. Make attaching the clamped earthing cable to the container the first step of filling.
Dip pipe: lower the filling pipe close to the bottom of the container; liquid falling freely and splashing produces both charge and vapour.
Initial flow rate: start filling slowly until the end of the pipe is covered by liquid.
Plastic containers: non-conductive containers cannot be earthed; address the use of plastic containers for solvent-based products separately in the risk assessment.
Personnel: Annex 2 of the explosive atmospheres regulation requires workers to be given antistatic personal protective equipment made of suitable material.

Earthing cables and clamps should be visually checked for soundness every day. The internal electrical installation and earthing are inspected once a year as part of the periodic inspection of work equipment.

Tank washing, waste solvent and dirty rags

Washing tanks with solvent at colour changes and during maintenance is one of the riskiest jobs in the plant. If the tank is to be entered, this is confined space work: nobody enters without measurement, ventilation, an attendant and a rescue plan. If welding or cutting is to be done on a tank or line, a hot work permit is obtained, and the tank is cleaned and its atmosphere measured first. Annex 2 of the explosive atmospheres regulation also requires work in hazardous areas to be subject to written instructions and a written work permit issued by an authorised person.

Dirty washing solvent should be collected in lidded, earthed containers and not left standing in the production area.

Fire preparedness: suppression arrangements and training

Fires in paint manufacturing are mostly flammable liquid fires. In this class, a water jet can spread the fire; foam systems and portable extinguishers suitable for flammable liquids come to the fore. We explain which extinguisher types suit which fire in our article on types of fire extinguishers. In your preparedness, check:

A bund or kerb in the raw material store and tank farm to contain spills, and arrangements to stop them reaching drains,
Where firewater and foam suppression water will flow,
Marking of electricity and natural gas shut-off points,
Keeping the chemical list and safety data sheets ready to hand to the fire brigade.

If the plant is in an OIZ (organised industrial zone), the plan needs to be aligned with the OIZ fire brigade; we cover this in our article on emergency coordination with the OIZ fire brigade. Our article on the chemical inventory is a good start for listing the chemicals in storage and production.

Teams need to learn, through hands-on practice, how to make a first response to a flammable liquid fire and when to withdraw. For the theoretical and practical training we provide, see our fire training page; for process-based assessment, see risk assessment; and for sector-specific notes, see our chemicals and plastics page.

Frequently Asked Questions

Is an explosion protection document needed in paint manufacturing?

Yes, if there is a possibility of an explosive atmosphere forming because of flammable solvent vapour or combustible dust. The employer prepares the explosion protection document before work begins; it includes the risk assessment, zone classification, suitability of equipment and the measures taken. The document is updated when significant changes are made.

Why is pigment dust dangerous when emptying it into a solvent tank?

Because at that moment a combustible dust cloud and solvent vapour are present in the same place, and the energy needed for ignition falls. Static charge generated by the bag sliding and rubbing can be an ignition source. Dust extraction, earthing, slow emptying and a suitable recipe order reduce this risk.

Why is the earthing cable attached first during filling?

Static charge forms as soon as liquid starts to flow. If the cable is attached after filling has begun, the accumulated charge can produce a spark as the clamp approaches the container. That is why the container and the filling system are connected first and filling starts afterwards; the cable is removed after filling has finished.

Why are varnish rags collected in a lidded metal bin?

Rags soaked in products containing alkyds and vegetable oils produce heat as they react with air. In rags left in a heap, this heat cannot escape and spontaneous combustion can occur. A lidded metal bin limits contact with air and the spread of fire.