Ultraviolet intensity sensor for Trojan disinfection systems, 40-degree type, with an output scaling of 20 mA corresponding to 100 W. A UV intensity sensor reads the germicidal output actually reaching the water at 254 nm, which is the only direct evidence that the reactor is still delivering its validated dose. Lamp output falls with age and quartz sleeves foul, and both show up here before they show up anywhere else, so the controller alarms on this reading rather than on lamp hours alone. Trojan intensity sensors of the same physical form are not interchangeable across different view angles and output scalings, so match the markings on the sensor being replaced rather than the shape of its body. Trojan part 794528, also supplied as an Aquafine/Evoqua part under W2T542752. Fits the following reactors: UVLogic 02AM15, 03AS20 and 06AL30; UVSwift SCA01 and SCA02; SCB03, SCB04, SCB06 and SCB08; SCC6, SCC06 and SCC30; SCD03, SCD06, SCD12, SCD18 and SCD30; UVSwift 10L30(S2); UVSwift D12. Contact us if you are unsure whether this part fits your UV system.