The Contrec Model 515 (Application GN02) is the analogue input version of the 515 natural gas flow computer, built to take a standard analogue signal (4-20mA, 0-5V or 1-5V) from vortex, turbine, or other analogue-output gas flowmeters. It also supports stacked analogue flow inputs, so you can extend the turndown range on an installation with more than one meter run, and it applies non-linear correction to match the meter’s actual calibration curve rather than a straight-line approximation.
Gas compressibility and density are calculated using the AGA-8 Detailed Characterization Method across gas mixtures of up to 21 components, and gross heating value is worked out to ISO 6976 and GPA 2172-96. This is the same calculation basis used for fiscal and custody transfer gas metering, so it’s suitable for billing-grade applications, not just internal monitoring.
In actual application, this application code is normally paired with an analogue flowmeter that’s already installed and just needs a proper flow computer in front of it. The 515 has an onboard adjustable transducer excitation supply so you can power the field transmitter directly, plus 4-20mA retransmission and dual RS-232/RS-485 Modbus RTU ports so it talks to most SCADA or DCS systems without extra conversion gear. It also keeps a built-in log of totalizers, averages, and alarms, so you have an audit trail if anyone questions the readings later.
Before we quote this, we would normally check the flowmeter’s analogue output range, whether it’s a single or stacked input setup, the gas composition (for the AGA-8 calculation), and what output signals your control system needs. Hope this helps.
