UV Lamp Technologies — Overview
A reference to the lamp technologies that appear in the simulator as
recommendedLampGuidance.preferredTypes. Continuously extended with
field experience.
Matrix — Which Technology When
| Technology | Peak wavelength | Power | Service life | Application |
|---|---|---|---|---|
| Low-pressure Hg (254 nm) | 254 nm (sharp) | 20–100 W | ~8,000–12,000 h typical | HVAC, water (standard) |
| Amalgam (254 nm, high output) | 254 nm | 100–1,000 W | up to ~16,000 h (coated) | High flow rates, cooling towers |
| Medium-pressure Hg (200–400 nm) | Broadband | 500–10,000 W | shorter than LP Hg | Turbid water, biofilm, UV curing |
| UV-C LED 265–280 nm | 265–280 nm | < ~0.2–1 W per chip | tens of thousands of h | POE drinking water, spot applications |
| UV-A LED 365–405 nm | 365 / 385 / 395 / 405 nm | up to several hundred W per module | long (LED-class) | UV curing (coatings, adhesives) |
| Excimer KrCl (222 nm) | 222 nm (sharp) | 50–200 W | shorter than Hg lamps | Far-UV-C, skin-friendlier, specialised |
| Excimer Xe (172 nm) | 172 nm (sharp) | variable | technology-dependent | Surface activation, curing pre-treatment |
Low-Pressure Hg (254 nm)
- Mechanism: low-pressure mercury-vapour discharge. The emission is effectively monochromatic, concentrated at the 254 nm (253.7 nm) mercury resonance line.
- Efficiency: roughly 35–40 % wall-plug efficiency under optimised cold-spot temperature and operating current — the highest of the common UV-C source technologies. Optimum radiant yield occurs at a cold-spot temperature of roughly 40–50 °C.
- Form factor: long tubes (similar to fluorescent tubes), often 60–150 cm.
- Cooling: passive (air) or active (water, for immersion sleeves).
- Maintenance: lamp replacement after roughly 8,000–12,000 h of typical service life; quartz-sleeve cleaning depending on water quality.
- Use cases: HVAC air ducts, drinking water (DVGW-certified systems), cooling-tower bypass and basin treatment.
Amalgam (High-Output Hg, 254 nm)
- A variant of the low-pressure lamp using a solid mercury-amalgam depot instead of free liquid mercury.
- The amalgam spots act as a vapour-pressure regulator, absorbing and releasing mercury as lamp conditions fluctuate, which keeps UV output stable across a wide ambient-temperature range (effective up to high surrounding temperatures of roughly 90 °C).
- This stability allows much higher loading: amalgam lamps deliver up to roughly 10× the UV power density of a conventional low-pressure mercury lamp.
- Advantage: fewer lamps per system at high throughput, hence fewer points of failure.
- Disadvantage: higher cost than standard low-pressure lamps.
- Service life: coated long-life amalgam lamps can reach up to
16,000 h while still retaining a high share (80–90 %) of their initial UV-C output.
Medium-Pressure Hg (Broadband 200–400 nm)
- A higher mercury vapour pressure broadens the emission into a polychromatic spectrum spanning UV-C, UV-B and UV-A (roughly 200–400 nm) at high intensity.
- Individual lamps reach several kilowatts of electrical power.
- Advantage: broadband UV can act on deeper water layers and on biofilm substrate; high power per lamp keeps lamp count low.
- Disadvantage: substantially lower efficiency (on the order of 15–20 %), high heat load, and shorter service life than low-pressure lamps.
- Use cases: UV curing (UV-A/B/C for complex coatings), cooling towers with poor water quality, ballast-water disinfection.
UV-C LEDs 265–280 nm
- Semiconductor-based UV-C generation using aluminium-gallium-nitride (AlGaN); under forward bias, injected electrons recombine with holes and release UV photons.
- Strengths: long potential service life, no mercury, instant on/off, selectable peak wavelength.
- Weaknesses (2025/2026): low power per chip and still-modest wall-plug efficiency. State-of-the-art commercial devices reach roughly 10 % wall-plug efficiency at ~200 mW and 265 nm, with rated lifetimes exceeding 20,000 h; volume production of the ~200 mW class is expected toward the end of 2026. Thermal management remains critical.
- Use today: point-of-entry (POE) drinking water for households, small spot applications, laboratory use.
- Outlook: efficiency and per-device power are improving; broader adoption beyond point-of-use systems depends on those gains continuing.
UV-A LEDs 365–405 nm (for Curing)
- A mature, well-established technology for UV curing.
- High-power modules are available; modern 385/395 nm devices commonly deliver irradiance levels exceeding 15–25 W/cm² in flood configurations, and considerably more in focused spot systems.
- Wavelength is chosen to match the curing chemistry: 365 / 385 / 395 / 405 nm. 365 nm favours deeper penetration and legacy chemistries; 395 nm is the mainstream choice for many modern inks and high-speed lines.
- Runs cool relative to mercury arc lamps, limiting heat input to the substrate.
- Use cases: conveyor-belt curing, spot bonding, digital printing.
Excimer KrCl (222 nm, Far-UV-C)
- Krypton-chloride excimer lamp with a sharp emission peak near 222 nm.
- Key property: at wavelengths below ~230 nm the radiation is strongly absorbed by the outer skin (stratum corneum) and the tear film, so it reaches living cells far less than 254 nm radiation does.
- Safety thresholds are under active revision: the ACGIH Notice of Intended Change places the proposed skin TLV at 222 nm in the range of roughly 150–500 mJ/cm² (substantially above the long-standing 25 mJ/cm² UV-C limit). Optical filtering is essential — unfiltered KrCl lamps emit longer-wavelength components that are not skin-safe.
- Use cases: occupied-space ("people-present") room disinfection, specialised pathogen inactivation.
- Disadvantages: shorter service life, higher cost, and less UV output per unit than mercury lamps.
Excimer Xe (172 nm)
- A specialised technology for surface activation: cleaning and modifying substrate surfaces at the molecular level prior to coating, and sterilising plastic surfaces.
- The 172 nm photon energy (~7.2 eV) is high enough to break the main bonds of organic molecules directly.
- The penetration depth at 172 nm is extremely short — on the order of hundredths of a millimetre — so the technology is not suited to flow-through water or room disinfection, only to surface treatment.
Decision Logic per Application
- HVAC / room air: low-pressure 254 nm (standard); KrCl 222 nm for occupied rooms.
- Drinking water, household (POE): UV-C LED 265–280 nm (low maintenance, compact) or low-pressure Hg.
- Drinking water, municipal: DVGW-certified low-pressure Hg; amalgam for high flow rates.
- Cooling-tower basins: low-pressure Hg (IP68, submerged); amalgam for large basins; medium-pressure only where turbidity demands broadband UV.
- Process water, inline: low-pressure Hg in a pipe reactor; amalgam at high throughput.
- Conveyor-belt food: low-pressure Hg with shatter protection (FEP sleeve); amalgam for wide belts.
- Conveyor-belt curing: UV-A LED 365–405 nm (preferred); medium-pressure Hg for complex multi-component coatings.
- Spot curing: UV-A LED with spot optics (focused); mercury point sources for special cases.
- Evaporator, internal: UV-C LED or low-pressure lamp with a reflector channel.
- Evaporator, external: low-pressure 254 nm; radiation shielding mandatory.
Where This Feeds In
recommendedLampGuidance.preferredTypesin eachtemplates/*.ts.- TODO: review every app-template lamp recommendation together with the user.
- TODO: a website comparison table — "Which lamp technology for my application?" — as a lead magnet.
Cross-References
- Wavelengths and Action Spectra — which wavelength is biologically effective.
- UV Lamp Anatomy — quartz envelopes, electrodes, fill gas, cooling.
- Ballasts and Drivers — driver electronics and placement.
- LED Area Emitters — UV-LED arrays for uniform area irradiation: construction, anatomy, wavelength options, application matrix.
- UV-LED Lifetime and Degradation — L70 modelling, thermal ageing, AlGaN degradation, UV-A vs UV-C asymmetry, maintenance thresholds.
Sources
This article draws on peer-reviewed literature, manufacturer documentation and the IUVA UV Disinfection Handbook. Manufacturers are named only as class examples, never as recommendations.
- IUVA UV Disinfection Handbook (Bolton & Cotton) — general UV-source reference.
- Peer-reviewed efficiency, ageing and safety studies (ResearchGate, NIH/PMC, Wiley, AIP, CORM) for low-pressure, medium-pressure, amalgam, UV-C LED and KrCl excimer characteristics.
- Manufacturer documentation (e.g. Heraeus Noblelight, LightSources, American Ultraviolet) for amalgam and low-pressure lamp specifications.
See the linked source records for the full citation list.