E3FA-DN21 is an M18 cylindrical diffuse NPN sensor from the E3FA family with 100 mA max output. It has a 100 mm sensing range and 0.5 msec response for small-part presence detection. Supply is 10-30 VDC with an M12 4-pin connector.
Protections and washdown rating
Three built-in protections—output reverse polarity, output short circuit, and power supply reverse polarity—cover the common failure modes during installation or wiring errors. The IP67/IP69K enclosure means this sensor survives high-temperature, high-pressure washdown cycles, making it a fit for food, beverage, and pharmaceutical lines where moisture ingress is the primary failure driver. Operating temperature spans -13 °F to 131 °F; stay within that range to avoid false readings from thermal drift on the photodiode.
Connection variant comparison
If replacing a pre-wired E3FA-DN112M, the -DN21 changes the termination: the -DN21 uses a 4-pin M12 connector instead of a 2-meter bare-wire cable. The sensing performance—100 mm diffuse range, red LED, light-on/dark-on selectable, 0.5 msec response—is identical. On a swap, you'll need an M12 cordset or a field-attachable connector to match the existing wiring; no change to the mounting or bracket. Versus the PNP variant E3FA-DP21, the output type is the only difference: -DN21 is NPN, -DP21 is PNP. All other specs—range, connection, protection, ratings—are shared. Swapping requires verifying the PLC input sink/source compatibility; supply and wiring are otherwise identical.