DigitalFlow™ GM868

Panametrics general-purpose gas
ultrasonic flowmeter
ApplicationsFeatures

The DigitalFlow GM868 flow transmitter is a complete
ultrasonic flow metering system for measurement of mostgases including:• Full-featured flowmeter package• Hydrocarbon gases• Vent gases• Biogases• Digester gases• Fuel gases• Waste gases• Incinerator air flow
• Vapor recovery• Stack gases• Other gases• Transducer removable under line pressure• No moving parts• No pressure drop
• Wide rangeability with 1500 to 1 turndown ratio• Non-obstructive flow measurement• Tolerance to dirty streams• Low maintenance• Suitable for high temperatures• Two-path measurement available for maximum accuracy

Panametrics ultrasonic general purpose
gas flowmeter
The DigitalFlow GM868 flowmeter uses the patented
Correlation Transit-Time™ method of ultrasonic flow
measurement to provide accurate, drift-free measurements,
without impeding or obstructing the flowt.

Wide range of pipe sizes and flow conditions
With its broad range of measurement velocities, and its ability
to measure flow in any pipe from small to very large, oneDigitalFlow GM868 meter does the job of several conventional
meters. It handles pipes from 1 to 120 inches in diameter (2.5cm to 3 m), and velocities from 0.1 to 150 ft/s (0.03 to 46 m/s)—
in either direction, in steady or pulsating flow.
For maximum accuracy, use a two-channel meter tomeasure along two different paths at the same location.
A two-channel meter can also measure the flow in two
separate pipes or at two different places in the same pipe.

No pressure drop, low maintenance
Since the DigitalFlow GM868’s transducers do not obstruct
the flow, they generally do not cause any pressure drop as
other types of flowmeters do. The DigitalFlow GM868 has noparts that foul or collect debris, and no moving parts to wearout. As a result, it requires no lubrication, cleaning or otherroutine maintenance.

Digital and analog output options
The DigitalFlow GM868 flowmeter makes it easy to send
the data where it needs to go, through the standard digital
output, standard or optional analog outputs or optional
alarms. All outputs are conveniently set up and calibrated
from the keypad or from a computer using the PanaView
program.

Transducer typeT5 wetted transducer

T17 wetted transducer
Flow measurement range

Standard range-150 to 150 ft/s (-50 to 50 m/s) - bidirectional
Applicable pipe sizes

Diagonal 45

3 in to 14 in (50 to 350 mm) OD

14 in to 120 in (350 to 3000 mm) OD

Bias 90

Note 1 and 2

Not applicable

Design velocity accuracy from 1 to 150 ft/s (0.3 to 50 m/s)
Transducer type
Number of Paths

T5 wetted transducer
One path

T17 wetted transducer

Two paths

One path

Two paths

1 ft/s(0.3 m/s)

>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)Pipe dia. </= 6 in.
(150mm)+-2.5%+-2.0%+-2.0%+-1.5%NANANANA

Pipe dia. >/= 6 in
(150mm)+-2.0%+-2.0%+-1.5%+-1.5%+-2.0%+-2.0%+-1.5%+-1.5%

Calibrated velocity accuracy from 1 to 150 ft/s (0.3 to 50 m/s) — see notes below
Transducer type
Number of paths

T5 Wetted Transducer
One pathT17 Wetted Transducer

Two paths

One path

Two paths

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)

1 ft/s(0.3 m/s)>3 ft/s(1 m/s)Pipe dia. </= 6 in.
(150mm)+-1.5%+-1.0%+-1.0%+-0.75%

NANANANA

Pipe dia. >/= 6 in
(150mm)+-1.0%+-1.0%+-0.75%+-0.75%+-1.0%+-1.0%+-0.75%+-0.75%

Flow velocity sensitivity from .1 to 1 ft/s (0.03 to .3 m/s)
Pipe dia. = 10 in.
(250 mm)±0.12 in/s (±0.004 m/s)

±0.08 in/s (±0.003 m/s)

NANA

Pipe dia. = 14 in.
(250 mm)±0.12 in/s (±0.004 m/s)

±0.08 in/s (±0.003 m/s)

±0.08 in/s (±0.003 m/s)

±0.06 in/s (±0.002 m/s)

Pipe dia. >/= 20in. (500 mm)±0.12 in/s (±0.004 m/s)

±0.08 in/s (±0.003 m/s)

±0.06 in/s (±0.002 m/s)

±0.04 in/s (±0.0015 m/s)

Note 1	Accuracy and sensitivity are dependent on pipe diameter, molecular weight and temperature. All accuracy specs
assume molecular weights greater than 24 kg/kmole and temperatures less than 100 °F (38 °C)
Note 2	Accuracy is dependent on straight run. All accuracy specs assume a fully developed flow profile or a minimum
straight run of 20D upstream and 10D downstream
Note 3	Stated accuracy may be achieved with total straight run as little as 10D using flow profile correction - contact factoryfor details

GM868 specifications
Operation and performance
Fluid types

All acoustically conductive gases

Pipe sizes

2 in to 120 in (50 mm to 3,000 mm) NB and larger

Pipe materials

All metals. Consult GE for other materials.

Flow accuracy (velocity)±1% to 2% of reading typicalAccuracy depends on pipe size and whether measurement is
one-path or two-path. Accuracy to ±0.5% of reading may beachievable with process calibration.

Repeatability

Display

Optional: 2 line x 16 character backlit LCD display,configurable to display up to four measurement parameters
in sequence

KeypadBuilt-in infrared, six-button keypad for full functionality
operationPower supplies• Standard: 100-240 VAC• Optional: 12 to 28 VDC, ±5%Note: For DC-powered meters, Class 2 rated supplies must be
used for the line power
Power consumption±0.2% to 0.5% of reading

20 W maximum

Range (bidirectional)

Operating temperature–150 to 150 ft/s (–46 to 46 m/s)

Rangeability (overall)
1500:1

Specifications assume a fully developed flow profile (typically
20 diameters upstream and 10 diameters downstream ofstraight pipe run) and flow velocity greater than 3 ft/s (1m/s).

Measurement parameters

Mass flow, standard and actual volumetric flow, totalized
flow, and flow velocity

Electronics
Flow measurement
Transit time

Enclosures••

Standard: Epoxy-coated aluminum Type 4X/IP66 Class I,Division 1, Groups B,C&D
Flameproof ISSeP 02ATEX008
II 2 GD EEx d IIC T5 IP66 T95°C
Optional: Stainless steel

Dimensions (h x d)Standard: Size 8.2 in x 6.6 in (208 mm x 168 mm), weight 10 lb(4.5 kg)

Channels••Standard: One channel
Optional: Two channels (for two pipes or two-pathaveraging)–4° to 131°F (–20° to 55°C)
Storage temperature–67° to 167°F (–55° to 75°C)
Standard inputs/outputs
Two 0/4 to 20 mA isolated outputs, 550 S maximum loadNamur NE043 compliant
Optional inputs/outputs
There are six additional slots available for any combination of
the following I/O boards:• Analog inputs: Select up to three boards of one of thefollowing types:–	Analog input board with two isolated 4 to 20 mAinputs
and 24V loop power– 	RTD input board with two isolated, three-wire, RTDinputs; span –100° to 350°C (–148° to 662°F); 100 S• Totalizer/frequency outputs: Select up to three totalizer/
frequency output boards, each with four outputs per board,
10 kHz maximum• Alarm relays: Select up to two boards of one of thefollowing types:– General purpose: Relay board with three Form C relays–	Hermetically sealed: Relay board with threehermetically sealed Form C relays

Digital interfaces
•
•
•
•
•
•

Standard: RS232
Optional: RS485 (multiuser)
Optional: Modbus® RS485 or TCP protocol
Optional: Ethernet
Optional: OPC server
Optional: Foundation fieldbus

Data logging••

Standard: None
Optional: Memory capacity (linear and/or circular type)tolog over 150,000 flow data points

European compliance

System complies with EMC Directive 2004/108/EC, 2006/95/
EC LVD (Installation Category II, Pollution Degree 2)andtransducers comply with PED 97/23/EC for DN<25

Wetted ultrasonic flow transducers
Temperature range••

Standard: –58°F to 302°F (–50C° to 150°C)
Optional (overall): –310°F to 842°F (–190°C to 450°C)

Area classifications••••

Standard: General purpose
Optional: Weatherproof Type 4X/IP66
Optional: Explosion-proof enclosure Class I, Division 1,Groups B, C, and D
Optional: Flameproof enclosure Class I, II 2 GD EEx dIIC T6Transducers and flowcells for specific applications areavailable. Consult Panametrics for details.

Transducer cables••

Standard: One pair of coaxial cables, type RG62 AU, or as
specified for transducer type
Optional: Lengths up to 1000 ft (330 m) maximum

High-temperature and high-pressure ultrasonicflow transducers
Bundle Waveguide Technology™ (BWT) System transducer
and holder (see BWT System specifications) are available.

Pressure range••

Standard: 0 psig to 2700 psig (1 bar to 187 bar)
Optional: 3480 psig (240 bar) maximum

Materials• Standard: Titanium• Optional: Monel® or Hastelloy® alloys

Process connections

Flanged and compression fittings

Mountings

Flowcell or cold tap

Panametrics, a Baker Hughes Business, provides solutions in
the toughest applications and environments for moisture,oxygen, liquid and gas flow measurement. Experts in flaremanagement, Panametrics technology also reduces flareemissions and optimizes performance.
With a reach that extends across the globe, Panametrics’
critical measurement solutions and flare emissions
management are enabling customers to drive efficiency
and achieve carbon reduction targets across criticalindustries including: Oil & Gas; Energy; Healthcare; Water andWastewater; Chemical Processing; Food & Beverage andmany others.
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(04/2023)

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