GF868 Flare Gas Flowmeter

GF868 Flare Gas Flowmeter

  • High Accuracy Patented Correlation Transit Time Technique - Calculates average molecular weight of hydrocarbon mixtures
  • Wide Pipe And Velocity Range 0.1 to 275 ft/s (0.03 to 85m/s) velocity in both directions and 3 in to 120 in (76mm to 3m) diameter pipe range
  • Ideal For Flare Gas Applications Ability to track leakage with positive material identification
Product Options


The DigitalFlow GF868 flare gas flow meter is ideal for flare gas applications due to its ability to track down leakage with positive material identification, reduce the cost of steam usage with proportional control and conserve energy by eliminating unnecessary flaring. The GF868 flow meter also complies with government regulations for pollution control and improves plant material balance. The GF868 meter is also ideal for the measurement of vent gas.

Advantages of the DigitalFlow GF868

  • No routine maintenance as there are no moving parts
  • High accuracy (due to the patented Correlation Transit Time technique, Digital signal processing and an accurate method of calculating molecular weight)
  • Fast response
  • Ultrasonic flow measurement does not interfere with the flows.
  • Designed for flare gas environments
  • Designed to deal with difficult problems such as bi directional flow, unsteady flow, varying compositions, wide flow range, pulsating pressure and harsh environments.
  • Wide velocity range: 0.1 to 275 ft/s (0.03 to 85 m/s) in both directions
  • Wide pipe range: 3 in to 120 in (76 mm to 3 m) in diameter
  • Transducers can be installed up to 1000 ft (300m) from the meter.
  • Dual channel version available

The DigitalFlow GF868 flare gas meter uses a patented method for calculating the average molecular weight of hydrocarbon mixtures. This proprietary algorithm extends the range for measuring the average molecular weight, while improving accuracy and compensating for non hydrocarbon gases better than ever before possible.

Ultrasonic flow measurement is the ideal technology when it comes to flare gas applications as it is fully dependent on gas properties and will not interfere with the flow of the gas. The all-metal transducers are installed into the pipes and each act as signal generators and receivers for the ultrasonic signals. These pulses are sent both upstream and downstream through the gas and the difference between these transit times each way is calculated. The onboard flow computer is then able to calculate velocity, volumetric and mass flow rate using the advanced signal processing and correlation detection. Temperature and pressure inputs enable the meter to calculate the standard volumetric flow. Maximum accuracy can be obtained by using the dual channel version to measure the two paths at the same point. The dual channel option can also be used on two points on the same pipe or on two different pipes.

Manufactured by: GE Panametrics
Model: GF868 Flare Gas Flowmeter

Services offered for this product

  • Sales
  • Rental
  • Installation
  • Calibration
  • Maintenance


Flare gas
Vent gas


Operation and Performance
Fluid Types Flare and vent gases
Pipe Sizes 2 in to 120 in NB (50 mm to 3,000 mm)
and larger
Pipe Materials All metals. Consult RS Hydro for other
Flow Accuracy (velocity) - 1 path measurement: ±2% to 5% of
reading at ±1 to 275 ft/s (±0.3 to 85
- 2-path measurement: ±1.4% to 3.5%
of reading at ±1 to 275 ft/s (±0.3 to
85 m/s)
Molecular Weight Accuracy (hydrocarbon mixtures) MW 2 to 120 gr/gr mole/±1.8%, optimizable
for other gas compositions
Mass Flow Accuracy (hydrocarbon mixtures) - 1-path: 3% to 7%
- 2-path: 2.4% to 5%
Dependent on accuracy of temperature
and pressure inputs.
Accuracy depends on pipe size and
whether measurement is one-path or
two-path. Accuracy to ±0.5% of reading
may be achievable with process
Repeatability ±1% at 5 to 100 ft/s (15cm/s to 30 m/s)
Range (bidirectional) -275 to 275 ft/s (-84 to 84 m/s)
Rangeability (overall) 2750:1
Measurement Parameters Mass flow, standard and actual volumetric
flow, totalised flow, and flow
Flow Measurement Patented Correlation Transit-Time mode
Enclosures • Standard: Epoxy-coated aluminum
weatherproof Type 4X/IP66 Class
I, Division 2, Groups A, B, C & DFM
and CSA
• Optional: Stainless steel, fibre-
Dimensions • Weight 11 lb (5 kg)
• Size (h x w x d) 14.24 in x 11.4 in x 5.12
in (362 mm x 290 mm x 130 mm)
Channels • Standard: One channel
• Optional: Two channels (for two
pipes or two-path averaging)
Display Two independent software configurable
64 x 128 pixel backlit LCD graphic
Keypad 39-key tactile-feedback membrane
Power Supplies • Standard: 100 to 130 VAC, 50/60 Hz
or 200 to 265 VAC, 50/60 Hz
• Optional: 12 to 28 VDC, ±5%
Power Consumption 20W maximum
Operating Temperature -4°F to 131°F (-20°C to 55°C)
Storage Temperature -67°F to 167°F (-55°C to 75°C)
Standard Inputs Two isolated 0/4 to 20 mA inputs (121
Ω) with integral 24 VDC power supply
For required temperature and pressure inputs
Standard Outputs • Six 4 to 20 mA outputs, software
assignable two outputs for 550 Ω
maximum load
• Four outputs for 1000 Ω maximum
Optional inputs / outputs There are four additional slots available
for any combination of the following
I/O boards:
• Analog outputs: Select up to three additional output
boards, each with four isolated 0/4 to
20 mA outputs, 1 k Ω maximum load
• Analog inputs: Select up to three boards of one of the
following types:
- Analog input board with two
isolated 4 to 20 mA inputs and 24V
loop power
- RTD input board with two isolated,
three-wire, RTD inputs; span -148°F
to 662°F (-100°C to 350°C); 100 Ω Pt
• Totaliser/frequency outputs: Select up to three totaliser/frequency
output boards, each with four outputs
per board, 10-kHz maximum. All
boards allow software selectable
functioning in two modes:
- Totaliser mode: Pulse per defined unit
of parameter (e.g., 1 pulse/ft3)
- Frequency mode: Pulse frequency
proportional to magnitude of parameter
(e.g., 10 Hz = 1 ft3/h)
• Alarm relays:

Select up to two boards of one of the
following types:
- General purpose: Relay board with
three Form C relays; 120 VAC, 28 VDC
maximum, 5A maximum; DC 30W
maximum, AC 60 VA
- Hermetically sealed: Relay board
with three hermetically sealed Form
C relays; 120 VAC, 28 VDC maximum,
2A maximum; DC 56W maximum,
AC 60 VA

Digital Interfaces • Standard: RS232
• Optional: RS485 (multiuser)
• Optional: HART® protocol
• Optional: Modbus® protocol
• Optional: Ethernet TCP/IP
Site parameter
Menu-driven operator interface using
keypad and “soft” function keys
Data logging Memory capacity (linear and/or circular
type) to log more than 43,000 flow
data points
Display functions • Graphic display shows flow in
numerical or graphic format
• Displays logged data and
European compliance Complies with EMC Directive 89/336/
EEC, 73/23/EEC LVD (Installation Category
II, Pollution Degree 2) and PED
97/23/EC for DN <25