Description

Key Technical Specifications

Parameter	Specification
Brand	Panametrics (GE / Baker Hughes)
Model	DIGITALFLOW XGM868I
Measurement Principle	Ultrasonic transit-time
Fluid Type	Gas
Channels	1-channel standard; 2-channel optional
Velocity Range	±150 ft/s (±46 m/s), bidirectional
Turndown Ratio	Up to 1500:1
Pipe Size Range	2 in to 120 in (50 mm to 3000 mm) and larger
Flow Accuracy	Typically ±1% to ±2% of reading; up to ±0.5% with calibration
Repeatability	±0.2% to ±0.5% of reading
Power Supply	90-260 VAC standard; 12-28 VDC optional
Analog Output	Two isolated 0/4-20 mA outputs standard
Communication	RS232 standard; RS485, Modbus, Ethernet optional
Enclosure	Epoxy-coated aluminum, NEMA 4X / IP66, hazardous-area rated
Operating Temperature	-40°C to 60°C (-40°F to 140°F)
Max Pressure	Up to 3480 psig (240 bar), system-dependent
Display	Optional 2-line × 16-character backlit LCD
Keyboard	Infrared 6-key, non-intrusive
Condition	New surplus, stock, or refurbished tested
Warranty	12 months

Product Introduction

The Panametrics DIGITALFLOW XGM868I is an ultrasonic transit-time gas flow transmitter designed for non-obstructive measurement of hydrocarbon gases, biogas, fuel gas, vent gas, stack gas, and other process gases. It supports single-path and dual-path configurations across pipes from 2 in to 120 in (50 mm to 3000 mm) and larger.Unlike differential-pressure or turbine meters, the XGM868I introduces no pressure drop and has no moving parts. It delivers a velocity range of ±150 ft/s (±46 m/s) with turndown up to 1500:1, making it suitable for wide-ranging or low-flow gas streams. Typical flow accuracy is ±1% to ±2% of reading, with ±0.5% achievable under calibrated conditions.

Installation & Configuration Guide

Preparation (10 min)

Record the transmitter nameplate: model, serial number, power supply, and I/O options.
Photograph all wiring labels, transducer cable tags, and DIP/jumper settings.
Confirm transducer type (wetted or clamp-on), cable length, and RG62 A/U coaxial cable requirement.
Verify pipe OD, wall thickness, material, gas composition, temperature, and pressure.
Prepare an ESD wrist strap, insulated tools, and a multimeter.

Removal (5–10 min)

Disconnect main power and verify zero voltage at the terminal block.
Label analog outputs, digital I/O, RS232/RS485, and transducer cables.
Disconnect transducer coaxial cables carefully; note channel assignment.
Remove mounting hardware and withdraw the transmitter.

Installation (10 min)

Mount the transmitter near the flowcell or transducer location to minimize cable length mismatch.
Ensure transducer cables are equal length within ±4 in when using non-OEM cable.
Reconnect transducer, analog, digital, and communication wiring per original labels.
Verify enclosure gasket seating and conduit seals for hazardous-area compliance.
Check that optional RTD and pressure transmitter inputs match the configured channel.

Power-On & Test (10 min)

Apply power and confirm display startup or LED status.
Check transducer signal strength and transit-time ratio.
Verify 4-20 mA outputs against known setpoints.
Confirm gas composition, pipe parameters, and temperature/pressure compensation entries.
Run a zero-flow check if process conditions allow.
Log firmware revision and configuration before returning to service.

Troubleshooting Quick Reference

Symptom	Likely Cause	First Check
No display / no power	Missing or incorrect supply voltage	Measure 90-260 VAC or 12-28 VDC at terminals
Low or unstable signal	Poor transducer coupling or cable fault	Inspect coaxial cable, connectors, and transducer mounting
Erratic flow reading	Wrong pipe parameters or gas data	Verify OD, wall thickness, gas type, temperature, pressure
Negative flow indication	Reversed transducer wiring	Check upstream/downstream cable assignment
4-20 mA out of range	Output scaling mismatch	Verify mA span, zero, and DCS/PLC input scaling
Communication failure	Wrong baud rate or RS485 polarity	Check RS232/RS485 settings and wiring polarity
Intermittent faults	Moisture ingress or corroded terminals	Inspect enclosure seal, terminal block, and conduit entries

Dimensions, Mounting & Wiring Notes

Dimensions: Approximately 8.2 in H × 6.6 in D (208 mm × 168 mm); weight about 10 lb (4.5 kg).
Mounting: Wall or pipe-mount via bracket; install near transducers to reduce cable losses.
Transducer Cables: Use RG62 A/U coaxial cable; match cable lengths within ±4 in.
Analog Outputs: Two isolated 0/4-20 mA outputs standard; additional outputs optional.
Communication: RS232 standard; RS485, Modbus, Ethernet, and fieldbus options vary by order code.
Hazardous Area: Verify enclosure certification matches the installation zone before energizing.

FAQ

Can the XGM868I measure natural gas and biogas?
Yes. It measures most gases, including hydrocarbon gases, biogas, digester gas, fuel gas, vent gas, and stack gas. Gas composition, temperature, and pressure must be entered correctly for accurate mass or standard-volume calculation.I still have a GM868 in the field. Can the XGM868I replace it?
Often yes. The XGM868I is the compact transmitter variant based on the GM868 platform. However, transducer type, cable length, I/O options, and firmware must be matched before substitution.Is this unit still sold new by Panametrics?
The XGM868I is a legacy product. Current supply typically comes from surplus stock or refurbished tested inventory. Lead time depends on available inventory and required I/O configuration.What happens if the transducer cables are different lengths?
Mismatched cables can degrade signal quality and introduce measurement error. Cables should be equal length within ±4 in, especially when non-OEM RG62 A/U cable is used.Does it support Modbus or Ethernet?
RS232 is standard. RS485, Modbus, Ethernet, OPC, and fieldbus options depend on the original configuration. Confirm the communication option before connecting to a DCS or PLC.Do you test these before shipping?
Function is verified under test conditions when testing is specified. Typical checks include visual inspection, power-up test, transducer signal verification, analog output check, and communication handshake. Full process validation requires site-specific gas and pipe data.