Sector·4 min read
Printing Press Fire Suppression Systems
Printing presses carry a high fire load due to the drying oven (dryer) in heatset web offset, flammable solvent-based inks in rotogravure and flexo, and fast-moving paper web. The most critical scenario is a web (paper band) break that lets paper pile up inside the hot dryer and ignite. Because printing presses usually sit in large-volume factory halls, CO2 local application (object protection) is more sensible than flooding the whole space; foam's disadvantages on the machine's sensitive electronic/control equipment are weighed project-based to select the right agent. This article covers CO2 for the dryer, local-application object protection, foam's effect on electronics and the project-based solution, solvent-vapor (LEL) monitoring, foam for storage, interlocks and static/ATEX measures.
A-Pro Engineering
Printing presses carry a high fire load due to the drying oven (dryer) in heatset web offset, flammable solvent-based inks in rotogravure and flexo, and the fast-moving paper web. This article covers printing-press fire safety along the axis of print type, with the logic of object protection in a large factory volume.
Risk profile: varies by print type
- Heatset web offset — after printing, paper passes through a hot dryer to cure ink; solvent vapor is released. A web (paper band) break is the most critical scenario: moving paper piles up in the hot dryer and ignites.
- Rotogravure / solvent flexo — inks contain Class I flammable solvent; vapor can form an explosive mixture.
- Common risks — ink/solvent storage, static electricity, paper dust.
We covered industrial facility fire safety in general in a separate article.
Why local application (object protection)?
Printing presses usually sit in large, open, high-ceilinged factory halls. Protecting such a volume by total flooding (filling it with gas):
- Requires an enormous quantity of CO2,
- Cannot hold the suppression concentration because of leakage through doors/openings,
- Creates an asphyxiation risk for personnel.
So on a printing press, local application (object/surface protection) is more sensible: CO2 is directed by nozzles not at the whole hall but straight at the hazard point — the dryer, the print unit, the ink pan and similar equipment. This provides suppression over and around the protected object even in an open area. Sizing follows the NFPA 12 (CO2) area/volume method; we covered the details in our CO2 local application article.
Web offset dryer protection
The traditional and most common solution for a heatset dryer is CO2 gaseous suppression: it acts fast, is a clean agent and causes no water/foam damage to the machine. Because the dryer is a closed volume, its interior can be protected by total flooding; the open parts of the machine are targeted by local application. Detectors sense flame/temperature rise inside the dryer and gas discharges.
The critical point is the interlock:
- On detection, web/machine stops,
- Dryer burner/heating is cut,
- Exhaust and feed are managed appropriately.
Oven/dryer safety is designed to NFPA 86 (Ovens and Furnaces) principles.
Foam’s disadvantages and project-based evaluation
Foam is a very effective agent on flammable-liquid fires; but in an electronics-dense environment like a printing press its disadvantages must be weighed properly. Printing presses contain drives, servo motors, PLCs, registration/color control systems, sensors and heavy wiring. Because foam is a wet, conductive, residue-leaving agent, when it gets onto/into this equipment it carries a secondary-damage risk:
- Corrosion and short circuits,
- Damage to control boards,
- Long cleanup and downtime.
This does not mean foam “cannot be used.” The correct approach is to evaluate by the equipment at the protected point and by the project:
- In the ink/solvent store and recovery area, where flammable liquid accumulates or flows, foam is in the right place.
- On the machine, where sensitive electronics dominate, clean and residue-free CO2 (local application) is a more suitable option in most projects.
The final decision is made project-based, weighing hazard class, liquid load and equipment type together.
Solvent printing: LEL monitoring and ATEX
In rotogravure and solvent flexo, the ink solvents are NFPA 30 Class I flammable liquids. Management is multilayered:
- Continuous LEL (lower explosive limit) monitoring at the print unit and solvent-recovery line,
- Hazardous-area classification (ATEX/Class I) for electrical equipment,
- Static control — grounding and ionization.
We covered area classification and detector selection in our fire detection and ATEX article.
Ink and solvent store
Inks, solvents and cleaners form a significant flammable-liquid load and are kept in a separate area. These areas are arranged to NFPA 30 principles: compartmentation, ventilation, spill containment and grounding. Foam is preferred for suppression (water alone is inadequate on flammable liquid) — this area, holding no sensitive electronics, is the right place for foam; we covered foam in a separate article.
Right agent, right zone
No single suppression agent fits everywhere in a printing plant; the choice follows risk and equipment:
- Printing machine / dryer → mostly CO2 local application (clean, fast, no harm to electronics or the machine),
- Solvent/ink store → foam (blankets the liquid surface; no sensitive electronics),
- Building in general, paper store, Class A load → water/sprinkler.
Because water can carry a flammable-liquid fire and foam carries a secondary-damage risk on sensitive electronics, these disadvantages are weighed project-based for the machine.
Summary
Printing-press fire safety is built on protecting the machine in a large factory volume with CO2 local application (object protection), and the heatset dryer with CO2 + web-burner interlock; foam’s disadvantages on sensitive electronics are weighed project-based — foam mostly finds its place in the ink/solvent store, while CO2 is generally preferred on the machine. Solvent printing adds LEL monitoring + ATEX + static control, and the building in general water/sprinkler. We also covered which building needs which system in our general article. At A-Pro Engineering we design integrated CO2 local-application object protection, dryer gaseous suppression, solvent/foam protection, LEL monitoring and interlocks for printing plants; contact us for your project.
This content is for information only. Binding design must be done project-specifically based on the print type, ink/solvent used and dryer conditions, and the editions in force of NFPA 12, NFPA 30, NFPA 86, ATEX and BYKHY.
© 2027 A-Pro Mühendislik. This is original technical content produced by A-Pro Engineering; all rights reserved. Copying, reproducing or republishing it in whole or in part without attribution and permission is prohibited.
Frequently asked questions
What is the biggest fire risk on printing presses?+
The most critical risk concentrates in the drying oven (dryer) of heatset web offset printing. After printing, the paper passes through a hot dryer to cure the solvent (mineral-oil) based ink, releasing solvent vapor. If the web (paper band) breaks, the moving paper piles up inside the hot dryer within seconds and readily ignites in the hot, solvent-laden environment. In rotogravure and some flexo printing, flammable solvent-based inks pose a direct Class I flammable-liquid risk. Add ink/solvent storage, static electricity and paper dust. Design therefore prioritizes the dryer and the solvent chain first.
Why is local application (object protection) CO2 preferred on a printing press rather than total flooding?+
Total flooding requires discharging the gas into a closed, tight volume and holding the suppression concentration there. But printing presses usually sit in large, open, high-ceilinged factory halls; flooding such a volume would need an enormous quantity of CO2, would be unreliable due to leakage through doors/openings, and would create an asphyxiation risk for personnel. So on a printing press, local application (object/surface protection) is more sensible: CO2 is directed by nozzles not at the whole hall but straight at the hazard point — the dryer, the print unit, the ink pan and similar equipment. This provides suppression over and around the protected object even in an open area. Local application is sized to NFPA 12 (CO2) by the area/volume method. The dryer, being a closed volume, can be protected by total flooding; the open parts of the machine are protected by local application.
What are the disadvantages of foam suppression on a printing press?+
Foam is a very effective agent on flammable-liquid fires; but in an electronics-dense environment like a printing press its disadvantages must be weighed properly. Printing presses contain drives, servo motors, PLCs, registration/color control systems, sensors and heavy wiring. Because foam is a wet, conductive, residue-leaving agent, when it gets onto and into this equipment it carries a secondary-damage risk of corrosion, short circuits and cleanup/downtime cost. This does not mean foam 'cannot be used'; the correct approach is to evaluate by the equipment at the protected point and by the project. In the ink/solvent store and recovery area, where flammable liquid accumulates or flows, foam is in the right place; on the machine, where sensitive electronics dominate, clean and residue-free CO2 (local application) is a more suitable option in most projects. The final decision is made project-based, weighing hazard class, liquid load and equipment type together.
How is a web offset dryer protected?+
The traditional and most common solution for heatset dryer protection is CO2 gaseous suppression; it acts fast, is a clean agent and causes no water/foam damage to the press. Because the dryer is a closed volume, its interior can be protected by total flooding; the open parts of the machine are targeted by local application. The system is triggered by detectors sensing flame/temperature rise inside the dryer, and gas discharges. The critical point is interlocking: when fire is detected the web speed/machine must stop, the dryer burner/heating must be cut, and exhaust and feed managed appropriately. Oven/dryer safety is designed to NFPA 86 (Standard for Ovens and Furnaces), and suppression to NFPA 12 (CO2) principles.
How is solvent risk managed in rotogravure and flexo printing?+
In rotogravure and solvent-based flexo printing, inks contain toluene-like flammable solvents; these are Class I flammable liquids under NFPA 30 and their vapors can form an explosive mixture. Management is multilayered: LEL (lower explosive limit) is continuously monitored at the print unit and solvent-recovery line, keeping the environment safely below that limit; electrical equipment is selected to hazardous-area classification (ATEX/Class I); static electricity is controlled with grounding and ionization. On the suppression side, CO2 local application (object protection) for the print unit and foam plus adequate ventilation for solvent storage and recovery are configured together.
How is the ink and solvent store protected?+
In printing plants, inks, solvents and cleaners form a significant flammable-liquid load and are usually kept in a separate store/area. These areas are arranged to NFPA 30 (Flammable and Combustible Liquids Code) principles: appropriate compartmentation, ventilation, spill containment and grounding. Foam-based systems are preferred for suppression (water alone is inadequate on flammable-liquid fires); this store, which holds no sensitive electronics, is the right place for foam. We covered foam selection and expansion ratio in a separate article. For small daily-use quantities, listed flammable-storage cabinets and limited-quantity rules apply.
Which standards and measures protect a printing plant?+
Rather than a single 'printing standard,' several standards are used together by risk area: NFPA 30 for flammable-liquid storage and use, NFPA 86 (Ovens and Furnaces) for drying-oven/dryer safety, NFPA 12 for CO2 suppression (total flooding and local application), NFPA 70 and ATEX for electrical classification in solvent-vapor areas, and foam standards for the solvent store. These are accompanied by static control, LEL monitoring, a hot-work permit system and regular cleaning (paper dust/solvent residue). In Türkiye, design is based on these standards together with BYKHY and OHS/ATEX legislation.
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