Propane gas (LPG) flow

Primary building heat is supplied via solar hot water panels. But this heat is supplemented by a propane gas boiler. Domestic hot water (sinks, showers, etc.) is provided by a propane instant hot water heater.

The propane is supplied by a tank outside the building. A regulator on the tank supplies propane gas at a pressure of 11 inches of water. A Rosemount model 8800C vortex flow meter is installed on the main gas supply line to the building to monitor propane gas flow. This transducer has a 4-20 mA output that is connected to an analog voltage input on the data logger with a 200 Ohm resistor shunt. The transducer produces a 4 mA signal with zero flow which translates into an 800 mV signal at the logger input. With full flow, 20 cfm, the transducer produces a 20 mA signal, that translates into a 4000 mV signal at the logger input.

The transducer was connected to the logger and setup on June 17. There is apparently an electrical noise problem in that the propane sensor indicates a fictitious, low-level, periodic flow synchronous with the regular, turning on and off of a nearby compressor.