top of page

UV Drying in The Printing Industry


This Technical Bulletin provides guidance to Consultants in relation to the fire risks presented by the use of UV dryers in the printing industry. A number of fires have occurred within such equipment in recent years, likely to be attributable to paper being ignited by the high temperature lamps positioned within the body of the dryers.

The Bulletin also provides information on Infrared Drying (IR), and general information on drying processes in other industries.

Consultants are reminded that any specific guidance contained within Client Service Instructions (CSI) for any particular Insurer Client MUST be adhered to.



The use and drying (also commonly referred to as “curing”) of UV curable inks and coatings in the printing industry has risen significantly in the past 20-30 years by providing a means of increasing the speed and quality of the drying process in a wide range of applications.

Conventional inks and coatings (water or solvent based) are dried through an evaporation process which removes approximately 40% of the delivered ink volume. By comparison, UV curing inks and coatings contain a “photoinitiator” which is a special compound sensitive to UV radiation. Exposure to intense UV radiation initiates a rapid catalytic reaction in the ink or coating, transforming it from liquid to solid state. Solvents are not required for this process; the product is cured rather than dried, as a result of which there is no loss of volume.

The heart of the process consists of a UV lamp which, broadly speaking, is constructed of a long sealed quartz tube which is filled with a starting gas and a small amount of mercury and has an electrode at each end. When high voltage is applied between the electrodes, the starting gas ionises and starts to heat up. The hot gas evaporates the mercury which emits radiation, a proportion of which is in the UV range.

Typical UV lamps

The main hazard associated with UV lamps relates to their high operating temperatures (commonly in the region of 850⁰C) and the potential risk of ignition of the printed material (substrate), either by direct contact or by remaining in close proximity to the lamp. Owing to the high operating temperatures, UV lamps will normally be employed in semi-sealed units which are air or water cooled. Like most high temperature lamps, several minutes need to elapse following isolation, before the lamp has cooled to a safe temperature.



This normally takes the form of one or more UV lamps installed within a purpose designed UV dryer positioned at the end and, in some cases, at intermediate locations in the printing press through which the substrate is passed. In virtually all applications, the substrate passes below the UV lamp, the distance between which will vary considerably depending on the application. Sheet-fed and web-fed press applications apply.

A Typical UV Drying System

Element list: (1) UV Lamphead with interchangeable cassette. (2) Control Screen.

(3) 9kW/12kW lamp controls. (4) Cooling Fan. (5) Flexible ducting. (6) Optional rigid ducting.

UV dryer in-situ on web-fed presses


A range of risk control measures in relation to equipment design can be considered, details of which are summarized below:

(As far as can be ascertained, such measures are incorporated as part of the normal design standard for dryers manufactured in the USA or within the EU, but reservations may exist in respect of equipment manufactured elsewhere where design criteria may be less onerous.)

  • Cooling arrangements (whether by air or water) suitably monitored and interlocked with UV dryer controls, providing automatic isolation of all lamps;

  • Drop sheet detection incorporated on sheet fed presses providing automatic alarms and dryer and press power down. This aims to detect via the press controls where a sheet has not fully passed through the system and is likely to be jammed in the dryer;

  • The provision of a rotating cold shutter around the UV lamp which automatically shields the substrate from heat when stopping the press. This is deemed essential for all web-fed press operations and is a best practice recommendation on sheet fed presses;

  • Automatic adjustment of UV power in line with machine speed.

  • Other fire safety management considerations include:

  • Ensuring that all staff are appropriately trained and instructed, including in emergency procedures;

  • The provision of suitable fire extinguishers in the immediate vicinity;

  • That all UV dryers are included in a planned, preventative maintenance programme in accordance with the manufacturers’ instructions, with full inspection and maintenance at least annually;

  • The installation of an appropriate LPCB approved, localized, automatic fire suppression system in and around the UV dryer, designed, installed and maintained by an LPS 1204 accredited contractor, with a certificate of conformity issued on completion. Such protection needs to be considered even where a premises is adequately sprinklered, as a fire within a press may destroy the press and cause a significant business interruption, before being brought under control by roof level sprinklers.. 

In addition to the fire hazards presented by UV dryers, radiation hazards also require consideration and should be assessed based on the information and guidance provided by the lamp/equipment manufacturers.

Similarly, manufacturers’ guidance concerning the safe disposal of used lamps should be observed with particular reference to the Waste Electrical and Electronic Equipment directive. HSE publication P40 Wide-format printing with UV-curable inks provides useful guidance on the range of potential health and safety issues.

Recent years has seen the development of UV LED curing technology, designed to improve the speed, performance and capabilities of a wide variety of curing applications. Owing to the low heat output of UV LED lamps as compared with traditional mercury vapour lamps, they are also much safer. Whilst UV LED technology is currently limited to smaller scale digital and screen-printing applications, future usage will undoubtedly expand in time. Some manufacturers have also developed low energy UV systems which are purported to reduce the risk of heat damage to substrates.


Infrared (IR) drying is a further drying process commonly encountered in the printing industry for use with conventional water or solvent based inks and coatings. Whilst the operating temperatures of infrared lamps are normally below those of UV lamps (in the range of 250-600⁰C), they nevertheless are capable of igniting combustible substrates and therefore require careful risk assessment and similar protection to that prescribed for UV lamps. This may include a recommendation for local fire suppression unless individual circumstances dictate otherwise.

The only significant hazard difference between UV and IR Drying is that IR lamps cool down more quickly and therefore would not normally incorporate cold shutter protection. In some cases, dryers are manufactured in which UV and IR lamps are interchangeable.


Inside an IR dryer


Whilst the main subject of this Technical Bulletin relates to UV dryers in the printing industry, it serves as a reminder of the potential hazards of process drying spanning a wide spectrum of trades and occupancies, and the need for Consultants to be particularly vigilant, the parameters for which should include:

  • The type of drying process employed, whether direct or indirectly heated, continuous or batch and the nature of the materials being dried;

  • The use of purpose designed and manufactured equipment, as compared with “homemade” dryers;

  • The method of heating – gas, electric, oil fired, steam, thermal fluid; temperature controls, appropriate safety interlocks etc.;

  • Dryers operated and maintained in accordance with the manufacturers’ instructions by alert and competent staff;

  • Where appropriate, documented emergency procedures in place;

  • Operating and supervisory control equipment regularly checked and tested, preferably weekly;

  • Unattended running;

  • Where appropriate, internal surfaces of dryers and extract systems routinely inspected and cleaned;

  • The provision of suitable fire extinguishers and local fire suppression systems as required.

Particular care should be taken when dealing with dryers or ovens in which flammable substances are released by evaporation arising from the drying or curing of coating materials, which should be included in the DSEAR risk assessment. In these circumstances, dryers should be designed and operated in accordance with BS EN 1539: 2015 Dryers and ovens in which flammable substances are released- safety requirements, which supersedes the earlier 2000 and 2009 versions of this standard.

Ovens designed prior to BS EN 1539 should incorporate the following minimum safety provisions:

•                 Appropriate shut off valves and combustion controls, including flame failure

•                 Devices and purging cycle, suitably interlocked;

•                 Explosion relief;

•                 Monitoring of local exhaust ventilation to ensure solvent vapours are <25% below

•                 The lower explosion limit (LEL);

•                 Annual check of solvent vapour levels within the dryer.

Note: This Technical Bulletin should be cross-referenced with RiskSTOP Technical Guidance Note 1 ‘The Printing Industry’.

bottom of page