https://h2oprotech.com/collections/general-purpose-flow-meters/products/flow-meter-3-wire
3/4" NPT Flow Sensor with Open Collector Output (3-wire) – H2OPro
General purpose flow sensor for accurately measuring real-time water flow. Unit has 3/4 inch NPT male fittings compatible with standard US PVC fittings.
open collector outputflow sensornptwire