DigitalFlow XGF868i - Flare Gas Ultrasonic Flow Meter


The XGF868i flare gas flow meter is a low-cost, compact, and explosion/flame-proof transmitter version of the GF868 flare gas flow meter, with CSA, ATEX, and IECEx certifications. Like the GF868 flow meter, the XGF868i improves the efficiency of petrochemical plants, refineries and offshore platforms. It uses a proprietary algorithm to determine instantaneously the molecular weight and mass flow rate of the flare gas. The meter is used to conserve energy and reduce product loss by identifying sources of leaks into flare systems. It also helps improve compliance with pollution control regulations and reduces energy usage by accurately controlling the amount of steam fed to the flare tip.

The XGF868i flow meter operates reliably even under unsteady flow, pulsating pressure, varying composition and temperature, harsh environments and the wide flow ranges typical of flare systems. Flow velocity is measurable from 0.1 to 394 ft/s (0.03 to 120 m/s) in pipes or stack sizes up to 120 in (3 m) in diameter. There are no moving parts or orifices to wear or clog. The XGF868i's flow measurement is independent of the gas properties, and it does not require regular maintenance.

  • Measures velocity, volumetric and mass flow
  • Delivers accurate flow rate, independent of gas composition
  • Measures instantaneous average molecular weight
  • High velocity range to 120 m/s (394 ft/s)
  • Accurate low flow rate measurement
  • 4000 to 1 turndown ratio
  • One or two path configurations
  • Allows cross flow immunity in large pipes
  • Minimal maintenance due to no moving parts, no holes or tubes, and tolerance to dirty or wet conditions
  • No pressure drop
  • Field-proven installation techniques
  • Easy serviceability

The DigitalFlow XGF868i flow meter is a complete ultrasonic flow metering system for:
  • Flare gas:
    • Track down or prevent losses from leakage with positive material identification
    • Account for total plant throughput of material
    • Reduce cost of steam usage with proportional control
    • Conserve energy by eliminating unnecessary flaring
    • Comply with government regulations for pollution control
  • Vent gas
  • Hydrocarbon gases
  • Biogases
  • Digester Gases

Operation and Performance

Fluid Types Flare and vent gases
Pipe Materials All metals, fiberglass. Consult GE for other materials.

Pipe Sizes 14 in to 120 in NB ANSI (350 to 3000 mm) Note 1
Flow Accuracy Velocity One Path Two Path Note 3
High Flow Range ±1.0 to ±394 ft/s
(±0.3 to ±120 m/s)
±2.0% ±1.5% Note 5
Low Flow Range ±0.1 to ±1.0 ft/s
(±0.03 to ±0.3 m/s)
±0.008 ft/s
(±0.002 m/s)
±0.0057 ft/s
(±0.0017 m/s)
Molecular Weight Accuracy 2 to 120 gr/gr mole ±1.8% of reading Hydrocarbon
Mass Flow Accuracy ±2.7% ±1.9% Note 2
Repeatability 1 to 394 ft/s
(0.3 m/s to 120 m/s)
0.1 to <1.0 ft/s
(0.03 to <0.3 m/s)
±0.5 to 1.0%

±5 to 6%
±0.35 to 0.75%

±3.5 to 4.0%
Rangeability (Overall) 4000.1

Note 1 - For pipe size 4 to 12 in NB, accuracy ranges from 1.5 to 4% for 1 f/s (0.3 m/s) and greater. Please consult GE for details.
Note 2 - Dependent on accuracy of temperature and pressure inputs
Note 3 - Accuracy stated assumes fully developed flow profile. Recommended minimum straight pipe is 20 diameters upstream and 10 diameters downstream. For 10 diameters upstream and 5 diameters downstream, accuracy is 5% for single path.
Note 4 - Consult GE for accuracy of non-standard transducer types.
Note 5 - Accuracy to 0.5% may be achieved with calibration.


Flow Measurement Patented Correlation Transit-Time mode
Enclosures Standard: Epoxy-coated aluminum
Optional: Stainless steel
Hazardous Area Rating:
Explosionproof: Class 1, Division 1, Groups B, C & D

Flameproof: ISSeP 07ATEX015,
II 2 G Ex d IIC T5 IP66
IECEx: FM G 0011X
II 2 G Ex d IIC T6 Gb IP66
Dimensions Standard: Size 8.2 in x 6.6 in (208 mm x 168 mm)
Weight: 10 lb (4.5 kg)
Channels Standard: Two channels (for two-path averaging)
Display 2 line x 16 character backlit LCD display, configurable to display up to four measurement parameters in sequence
Keypad Built-in infrared, six-button keypad for full functionality operation
Power Supplies Standard: 100 to 240 VAC
Optional: 12 to 24 VDC, ± 5%
Power Consumption 20W maximum
Operating Temperature –40°F to 140°F (–40°C to 60°C)
Storage Temperature –67°F to 167°F (–55°C to 75°C)
Standard Inputs Two 4 to 20 mA isolated inputs, 24 VDC loop power, or
One 4 to 20 mA isolated input, 24 VDC loop power, and
One direct three-wire RTD (temperature) input, -148°F to 662°F (-100°C to 350°C), 100 Ω platinum
Standard Outputs Two 0/4 to 20 mA isolated outputs, 600 Ω maximum load
Optional Inputs/Outputs Two frequency outputs, optically isolated, 3 A maximum, 100 VDC maximum, 1 W maximum, from DC to 10 kHz maximum
Digital Interfaces Standard: RS232 (PanaView PC software) HART® protocol on 4-20 mA output
Optional: Modbus® RS485 or TCP/IP
Optional: Ethernet
Optional: OPC Server
Optional: Foundation Fieldbus®
Display Functions Graphic display shows flow in numerical or graphic format
Displays logged data and diagnostics
European Compliance Complies with EMC Directive 2004/108/EC, 2006/95/EC LVD (Installation Category II, Pollution Degree 2) and transducers comply with PED 97/23/EC for DN<25

Descriptions English
Computational Fluid Dynamics Computational Fluid Dynamics
DigitalFlow XGF868i Datasheet DigitalFlow XGF868i Datasheet
DigitalFlow XGF868i Programming Manual DigitalFlow XGF868i Programming Manual
DigitalFlow XGF868i Service Manual DigitalFlow XGF868i Service Manual
DigitalFlow XGF868i Startup Guide DigitalFlow XGF868i Startup Guide
T17 Installation Guide T17 Installation Guide
T17 Transducer Datasheet T17 Transducer Datasheet
T5 Installation Guide T5 Installation Guide