Lamp Power Tool - UVResources

UV-C POWER CONVERSION CALCULATOR

This tool helps HVAC engineers convert UV-C lamp power into irradiance, energy, and dose values for coil irradiation applications. Enter per-lamp watts, number of lamps, coil area (ft² or inches), or irradiance, and the calculator will fill in the rest. Results include UV dose (J/ft², mJ/ft², µJ/ft²), lamp power density (W/ft², J/ft², µW/ft²), and ASHRAE conformance.

Assumes uniform distribution across the coil face; irradiance & dose use UV output factor k = 0.159.

Lamp Power

Individual Per–Lamp Power (W)*[scroll to lamp watt chart]Per–Lamp Power (mW)Number of Lamps*TOTAL Lamp Power (W)

Coil Area & Irradiance

Width (in)*Height (in)*Coil Area (ft²)*Irradiance (µW/ft², avg over coil face)

Exposure Time & Energy

Duration (s)

Total Energy (J, system-wide)

UV Dose (avg over coil face)

UV Dose (J/ft²)UV Dose (mJ/ft²)UV Dose (µJ/ft²)

Lamp Power Density

Lamp Power Density (W/ft², input power basis)Energy Density (J/ft², input power × time)Equivalent Irradiance (µW/ft², recomputed)UV Output Density (UV-W/ft²)

ASHRAE Conformance

Typical ASHRAE coil irradiation design guidance targets an electrical lamp power density of ≥ 6 W/ft² across the coil face to maintain clean coils and suppress microbial growth.

Electrical Power Density (W/ft²)Electrical Power Density (W/cm²)UV Output Density (UV–W/ft²)UV Output Density (UV–W/cm²)Equivalent Irradiance (µW/cm², UV basis)

Awaiting calculation…

Conformance is evaluated on the electrical W/ft² basis. Legend: Green = Within (≥ 6 W/ft²). Red = Below 6 W/ft².

Assumptions: values are averaged over coil face (ft² basis). Irradiance & dose estimated with UV output factor k = 0.159 (UV_W = Lamp_W × 0.159). Actual values vary with lamp type/ballast, temperature, aging, quartz soiling, reflectance, view factors, and placement.

UV-C LAMP WATTAGES BY LAMP LENGTH

This chart provides a quick reference to UV-C lamp electrical wattage output based on lamp length across the UV Resources product families (RLM[X], DE[X], SL[X], SLN[X], DLN[X], and X PLUS). Each section highlights the nominal lamp length (in inches) paired with its corresponding lamp wattage (W). This data helps engineers, contractors, and facility managers:

Match lamp lengths to wattage requirements when designing or retrofitting UV-C systems.
Compare performance across product families.
Simplify specification and ordering by showing standardized lamp options.

PRODUCT		LAMPS
RLMX	LENGTH	33	36	42	61
	WATTS	75	80	98	145
(2) TOTAL	P	150	160	196	290
(4) TOTAL	P	300	320	392	580
(6) TOTAL	P	450	480	588	870

DE[X]	LENGTH	24	36	42
	WATTS	40	69	92

SL[X]	LENGTH	16	20	24	30	36	42	61
	WATTS	38	47	58	71	85	98	145

SLN[X]	LENGTH	16	220	24	30	36	42	61
	WATTS	38	47	58	71	85	98	145

DLN[X]	LENGTH	12	16	20	24	30
PER LMAP	WATTS	28	38	47	58	71
SYSTEM	WATTS	56	76	94	116	142

X PLUS	LENGTH	17	23	33	36	45	60
	WATTS	11	26	41	46	61	73

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ASHRAE GUIDELINE REFERENCE

According to ASHRAE Handbook — HVAC Applications – Chapter on Ultraviolet Lamp Systems, typical coil irradiation designs aim for 6–12 W/ft² of coil face area to maintain a clean coil surface and suppress microbial growth.

For further details, see the official ASHRAE resource:
ASHRAE UV-C Disinfection Guidelines