UV LAMP

A comprehensive list of UV industry related terms and their definitions;

Air deposition The occurrence of airborne pollution (eg. mercury) falling to the ground in precipitation, dust, due to gravity. Also known as “atmospheric deposition”.

Conformal Coating A protective non-conductive dielectric layer that is applied onto the printed circuit board assembly to protect the electronic assembly from damage due to contamination, salt spray, moisture, fungus, dust and corrosion caused by harsh or extreme environments.

Devitrification Crystallisation of a formerly non-crystalline (amorphous) glass such that its ability to transmit a range of electromagnetic radiation (e.g. UV) is greatly reduced.

Dichroic Describes materials with the property to selectively reflect or transmit a particular wavelength range. Dichroic UV reflectors that reflect less long wavelength radiation such as IR are called “cold mirrors” while those that reflect more are called “hot mirrors”.

Dielectric An electrical insulator that can be polarised by an applied electric field.

Dielectric Strength The maximum electric field a material can withstand intrinsically before it breaks down and becomes a conductor of electricity.

Discharge Tube / UV Lamp Is a lamp envelope containing electrodes, a starting gas that is ionised by an electric field and other additives. The additive atoms / ions are excited to high energies and emit a UV photon as they return to their ground state.

Doped Lamp Also known in the industry as a metal halide lamp, contains an additive, such as gallium or iron, to alter the spectral output in order to cure different types of inks / coatings / adhesives.

Electric Arc An electric current involving an ionised gas, such as argon, leading to the formation of a plasma arc.

Electric field In simple cases, the electric field between two points is the voltage between those points divided by the distance between them.

Electrical Ballast / Choke / Transformer A device to prevent excess current into a lamp and can also assist in lamp ignition.

Electromagnetic Spectrum / Radiation The entire range of all possible electromagnetic radiation. This includes gamma rays, X-rays, ultraviolet, visible light, infra-red, microwaves and radio waves.

Elemental (Metallic) Mercury Is one of the three chemical forms of mercury, which usually causing health effects when inhaled in vapour form. Exposures can occur when elemental mercury is spilled or products that contain elemental mercury break and expose mercury to the air, particularly in warm or poorly-ventilated indoor spaces.

Ground State The lowest energy state of an electron.

Halogen Chemical elements in Group XVII of the periodic table, including fluorine, chlorine, bromine, iodine and astatine.

Infra-Red (IR)The band of the electromagnetic spectrum ranging between 750nm to 1mm.

Isopropyl (Isopropanol) Alcohol A colourless and relatively non-toxic alcohol. It evaporates quickly and can dissolve various oils, so is useful for cleaning quartz cooling tubes, UV reflectors and UV lamp bodies.

Metal Halide A chemical compound involving a metal and a halogen.

Methylmercury An organic mercury compound formed through microbial activity when mercury is introduced to a water supply. This is harmful to aquatic wildlife and animals (including humans) that ingest them.

Molybdenum A silvery metal with the chemical symbol Mo and atomic number 42. It has the sixth-highest melting point of any element. It is frequently used for making steel alloys as well as in the seal for UV lamps due to its relatively low thermal expansion and high electrical conductivity.

Nanometre (nm) A term used in industry to measure specific wavelengths of the electromagnetic radiation spectrum – One billionth of a metre, 1 millimetre = 1000th of a metre, 1 micrometre = 1000th of a millimetre, 1 nanometre = 1000th of a micrometre One billionth of a metre, 1 millimetre = 1000th of a metre, 1 micrometre = 1000th of a millimetre, 1 nanometre = 1000th of a micrometre

Noble Gases Chemical elements in Group XVIII of the periodic table with similar properties such as being odourless, colourless and of low reactivity. This includes helium, neon, argon, krypton, xenon and radon.

Photo-Initiator A compound that undergoes chemical reaction(s) when subjected to electromagnetic radiation.

Photopolymerisation Is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks.

Phototherapy the use of UV light in the treatment of physical or mental illness.

Photochemotherapy Also known as PUVA is the use of UV light in the treatment of cancer.

PUVA stands for psoralen (P) and ultraviolet A (UVA) therapy. This is a UV Light therapy used to treat skin contritions such as eczema and vitiligo.

Quartz A glass-like material made of silicon dioxide (SiOâ‚‚) with various different forms. It has low thermal expansion and a very high melting point of around 1665 °C. The 'fused quartz' form transmits UV very effectively.

Spectral Enhancement Moving the electromagnetic radiation output of the UV lamp, by doping with certain additives. This may include increasing the intensity of the radiation, or shifting the range of wavelengths (nm) of the radiation.

Thin Layer Chromatography (TLC) A process involving UV light which chemists use to identify the components in a mixture.

Transformer An electrical device used to step-up or step-down the voltage of alternating currents.

Tungsten Is a chemical element with the chemical symbol W and atomic number 74. Tungsten and its alloys are used in numerous applications such as light bulb filaments, and it is used to make UV lamp electrodes owing to having the highest boiling point of any metal.

Tungsten Electrodes A conductor through which electricity enters a UV lamp.

UVA Also known as “Longwave UV”. UVA has a wavelength range of 400 — 315 nm. It is the least harmful of the three UV wavelengths but can still contribute to the ageing of skin, DNA damage and possibly skin cancer. UVA lamps are used for curing of inks, adhesives and coatings and specifically; screen printing and flexo printing.

UVB Also known as “Midwave UV” or “Medium Wave UV”. UVB has a wavelength range of 315 – 280 nm. It is more dangerous than UVA and is responsible for burning the skin among other things. In industry UVB lamps are used for curing of inks, adhesives and coatings and specifically clear coatings and thin ink layers.

UVC Also known as “Shortwave UV”. UVC has a wavelength range of 280 – 100 nm. It is the most harmful and highest energy of the three UV wavelengths. In industry UVC is used for water and air disinfection as it can render micro-organisms harmless.

UV Coating Refers to treatment of a substrate with UV radiation to cure the surface or protect the underlying material from its harmful effects.

UV Curing Is a photochemical reaction (photopolymerisation) when specialised coatings are exposed to UV light they cure, instead of relying on heat and time to evaporate carriers like in solvent-based coatings.

Wavelength A property of electromagnetic radiation – by altering the wavelength (nm) you can cure / disinfect various types of substrates.

WEEE The Waste Electrical and Electronic Equipment Directive (WEEE Directive) is the European Community directive 2002/96/EC on waste electrical and electronic equipment (WEEE).

Photoinitators & Doped Lamps

Different photoinitiators such as inks, adhesives and varnishes respond to different wavelengths (nm) of UV light in order to cure.

Metal Halide (doped) lamps are effectively mercury lamps but with additional additives. These additives modify the spectral output and enhance certain wavelengths nanometres (nm).

Most curing photoinitiators are activated using near UV (200-400nm range)

• UV-A (315-370 nm): curing bulk substrate (e.g. print press, labels and packaging)

• UV-A (370-400 nm): curing heavier inks/substrates (e.g. silk screen, Japanese)

• UV-V (400-450 nm): deep penetration for thick layers like varnishes (e.g. furniture)

• UV-B & UV-C: (100-315) used in conjugation with UV-A to cure the very surface of substrate

Spectral Output = UV Radiant Output Vs. Wavelength

Mercury Vapour Lamp: 254nm – 365nm

• Typical ink, polymer and resin manufacturers in Europe and the Americas are designed to cure around 365 nm wavelengths

The UV Lamp Engineers have prepared some useful tips to help you to increase the life of your lamps;

To ensure that we continue to provide the best possible service to all customers; please read this information, as it will help you to maximise the life length of your Alpha-Cure lamps.

Avoid Excessive Starts

When a lamp is first started, the internal pressure is low. The electrodes during this time are emitting poorly, throwing or spitting off tungsten into the lamp. This causes points of contamination which can result in premature failure of the lamp.

Lamps should typically be started at a high power to reduce the length of time they are in the starting mode. Excessive starts cause premature darkening of the ends, this will result in a drop in output as the darkening eventually migrates into the body of the lamp.

Advice: Whenever possible, gather all of the work to be done, start the lamp and perform all of the work that can be done during this time. Remember to avoid stopping and starting the lamps.

Check Lamp, Reflectors and Cooling System

Curing often fails due to poor lamp and system maintenance. It is rarely due to problems with the lamp itself. Regular ‘preventative maintenance' will reduce the chance of lamp failure and system breakdown. Below are a few simple steps which we recommend should be followed regularly, ideally after every 500 hours of operation, to increase the operating lifetime of your Alpha-Cure lamp and curing system.

Clean the lamp regularly to remove any residue which can cause devitrification. Lamps should always be handled using gloves and cleaned with isopropanol.

Check to see that your reflectors are clean and free of distortion from the lamp's radiated heat. Periodic cleaning and/or replacement of reflectors may be necessary to maintain maximum efficiency of both the lamp and equipment. Accumulated dirt on the blower blades blocks air flow and reduces cooling. Lamps running too hot can sag or expand causing a drop in the running voltage and wattage and a reduction in output.

Cleaning the blades improves cooling which can discourage a lamp from sagging. Sometimes lamps sag unnoticeably, so it is always a good idea to rotate them periodically. Clean the power supply and system air filters which may be clogged with dust. Check any flexible ducting for holes or splits which may reduce extraction and cooling. Clean the system (i.e. chassis and shutter).

Advice: Regular maintenance of the lamp and reflectors is highly recommended, clean them as often as possible and replace when necessary. Rotate the lamp when you clean or replace your reflector.

Install Lamps with Care

To lengthen a lamps life, follow the O.E.M.'s installation instructions carefully. For example, avoid finger oil on the lamp body by using a paper towel or gloves. The use of an alcohol wipe is also recommended to assure clean surfaces.

It is important to insure that the electrical connections are tight and not corroded.

In the case with spring loaded sockets (such as Hanovia type), it is imperative that the sockets are in good shape with proper spring tension and clean contact surfaces.

Lamps that are held rigid in their mounts should not be held so tight as to restrict movement as the reflectors expand, contract and warp during operation. More attention may be needed for lamps that do not have leads for their electrical connection.

With lamps in which the electrical connection is made through the mounting clamp, this area should be tight and clean. In this case, most manufacturers accommodate some flexibility with the mount. Obviously, spring clip type mounts must have good tension. Most lamps in this category are small, exposure type, and expansion is not as much of a factor.

Advice: Follow the OEM's installation instructions and ensure that the lamp is fitted correctly. Use gloves to or a paper towel to avoid putting any finger oil on the lamps.

We hope that this information is of use to you, and your customers, and will help you to maximise the use of your Alpha-Cure lamps. Please do contact us, if we can be of any further assistance.

Curing often fails due to poor lamp and system maintenance. It is rarely due to problems with the lamp itself. Regular ‘preventative maintenance' will reduce the chance of lamp failure and system breakdown. Below are a few simple steps which we recommend should be followed regularly, ideally after every 500 hours of operation, to increase the operating lifetime of your Alpha-Cure lamp and curing system.

Clean the lamp regularly to remove any residue which can cause devitrification. Lamps should always be handled using gloves and cleaned with isopropanol.

Check to see that your reflectors are clean and free of distortion from the lamp's radiated heat. Periodic cleaning and/or replacement of reflectors may be necessary to maintain maximum efficiency of both the lamp and equipment. Accumulated dirt on the blower blades blocks air flow and reduces cooling. Lamps running too hot can sag or expand causing a drop in the running voltage and wattage and a reduction in output.

Cleaning the blades improves cooling which can discourage a lamp from sagging. Sometimes lamps sag unnoticeably, so it is always a good idea to rotate them periodically. Clean the power supply and system air filters which may be clogged with dust. Check any flexible ducting for holes or splits which may reduce extraction and cooling. Clean the system (i.e. chassis and shutter).

Advice: Regular maintenance of the lamp and reflectors is highly recommended, clean them as often as possible and replace when necessary. Rotate the lamp when you clean or replace your reflector.

To lengthen a lamps life, follow the O.E.M.'s installation instructions carefully. For example, avoid finger oil on the lamp body by using a paper towel or gloves. The use of an alcohol wipe is also recommended to assure clean surfaces.

It is important to insure that the electrical connections are tight and not corroded.

In the case with spring loaded sockets (such as Hanovia type), it is imperative that the sockets are in good shape with proper spring tension and clean contact surfaces.

Lamps that are held rigid in their mounts should not be held so tight as to restrict movement as the reflectors expand, contract and warp during operation. More attention may be needed for lamps that do not have leads for their electrical connection.

With lamps in which the electrical connection is made through the mounting clamp, this area should be tight and clean. In this case, most manufacturers accommodate some flexibility with the mount. Obviously, spring clip type mounts must have good tension. Most lamps in this category are small, exposure type, and expansion is not as much of a factor.

Advice: Follow the OEM's installation instructions and ensure that the lamp is fitted correctly. Use gloves to or a paper towel to avoid putting any finger oil on the lamps.

We hope that this information is of use to you, and your customers, and will help you to maximise the use of your Alpha-Cure lamps. Please do contact us, if we can be of any further assistance.

When a lamp is first started, the internal pressure is low. The electrodes during this time are emitting poorly, throwing or spitting off tungsten into the lamp. This causes points of contamination which can result in premature failure of the lamp.

Lamps should typically be started at a high power to reduce the length of time they are in the starting mode. Excessive starts cause premature darkening of the ends, this will result in a drop in output as the darkening eventually migrates into the body of the lamp.

Advice: Whenever possible, gather all of the work to be done, start the lamp and perform all of the work that can be done during this time. Remember to avoid stopping and starting the lamps.