I use an inline Endress + Hauser 63 series Coriolis mass flow sensor on my HERMS loop. It has analog outputs for temperature and gravity, and frequency for flow rate. I use an Arduino to capture the data which sends to a micro PC running Node-Red via MQTT. From Node-Red I’ve got a couple embedded dashboards for gauges and control (timing, temps and recipe importing) and send to Grafana for datalogging (as pictured).
One can find mass flow sensors on eBay for a relatively good price if you know what you’re looking for. Most all have analog outputs, it’s just a matter of finding the right size, with the right options for the right price. I bought this specific one for ~$350 shipped.
Cheers,
Matt