DigitalFlow™
XMT868i

Panametrics liquid flow
ultrasonic transmitter
ApplicationsFeatures

The DigitalFlow XMT868i liquid flow transmitter is a complete
ultrasonic flow metering system for measurement of:• Economical, nonintrusive flow measurement• Hydrocarbon liquids• Liquefied natural gas (LNG)• Crude oil• Lubricating oils
• Diesel fuel oils
• Solvents• Water and wastewater• Hot/chilled water• Chemicals• Beverages• Other liquids• Hazardous (classified) location certification• Simple setup and installation• Suitable for a wide range of pipe sizes and materials• Two-channel/two-path version available• Energy measurement option• Large backlit LCD display• Velocity, volumetric and energy flow rates• Totalized flow and trend data

Panametrics liquid flow ultrasonic transmitter
The DigitalFlow XMT868i ultrasonic flow transmitter combines
state-of-the-art flow measurement capability with a
low-cost transmitter package that can be installed rightat the process measurement point. The XMT868i carries
appropriate certification for installation in hazardous(classified) locations commonly found in petrochemical andchemical processing environments.
The all-digital XMT868i has no moving parts, requires
minimal maintenance and provides long-term, drift-free
operation. An onboard microprocessor provides exclusive
digital signal coding and correlation detection routines,
automatic adjustment to changing fluid properties, anddynamically-configured operating software to simplify
programming.

DigitalFlow XMT868i shown with clamp-on transducers

Improved programming capability

Wetted or clamp-on transducers

The DigitalFlow XMT868i introduces an infrared six-button
keypad to allow safe programming and diagnostics
verification in your hazardous (classified) location. There isno need to open the case to use a PC to program and noneed for an additional handheld programmer. Just touch
the glass of the XMT868i and the IR buttons will sense yourtouch. If you prefer your PC interface, the DigitalFlow XMT868i
maintains its RS232 capability, providing full access to themeter’s diagnostics and programming using PanaView™
software. PanaView also provides continuous logging
capability.

Clamp-on transducers offer maximum convenience,
flexibility and a low installation cost compared to traditional
flow metering technologies. With proper installation, wetted
transducers provide maximum accuracy (better than 0.5
percent of reading) in most applications.

Dual-channel version reduces costs andimproves performance
The optional dual-channel/dual-path model can be userconfigured for a variety of applications. It can be set up tomeasure flow in two separate pipes with one meter to reducethe cost-per-measurement point.

Ultrasonic flow transducers are classified as either wetted
or non-wetted (clamp-on). Clamp-on transducers areclamped onto the outside of the pipe and never come into
contact with the process fluid. Wetted transducers aremounted into the pipe or flowcell in direct contact with theprocess fluid.

The DigitalFlow XMT868i can be used with a variety ofwetted solutions including the PanaFlow™ system. The
PanaFlow meter system relies on the XMT868i as an integral
component to simplify installation. A DigitalFlow XMT868i
is easily mounted to the top of a PanaFlow system and isshipped ready to install.

To minimize the effects of flow profile distortions, flow swirl
and cross flow, and for maximum accuracy, you can install
the two sets of transducers on the same pipe.

RH-Plus MR2350 dimensions

Flowmeter transducers

DigitalFlow XMT868i flow transmitter uses
transit-time flow measurement technique
Fluid flow

Flowmeter transducers

Ultrasonic signal path
Fluid flow

Ultrasonic signal path
Transit-time flow measurement techniqueIn this method, two transducers serve as both ultrasonicsignal generators and receivers. When mounted on apipe, they are in acoustic communication with each other,
meaning the second transducer can receive ultrasonicsignals transmitted by the first transducer and vice versa.
In operation, each transducer functions as a transmitter,
generating a certain number of acoustic pulses, and then asa receiver for an identical number of pulses. The time interval
between transmission and reception of the ultrasonic signals
is measured in both directions. When the liquid in the pipe is
not flowing, the transit-time downstream equals the transittime upstream. When the liquid is flowing, the transit-time
downstream is less than the transit-time upstream.
The difference between the downstream and upstream
transit times is proportional to the velocity of the flowing
liquid, and its sign indicates the direction of flow.

Automatically adjusts to changing
fluid properties
Standard in all DigitalFlow XMT868i transmitters, our unique
Automatic Tracking Window™ (ATW™) feature ensuresaccurate flow measurements even when fluid properties are
unknown or changing. Like the seek mode on your car stereo,
ATW dynamically sweeps the receiver window whenever thesound speed of the fluid changes. This powerful feature lets
you measure flow when the fluid sound speed is unknown,
is changing due to large temperature shifts, or when a newliquid starts to flow in a multiproduct pipeline.
ATW works for both clamp-on and wetted transducer
applications by searching for a reliable ultrasonic receive
signal. It does this by varying the time between the transmit
signal and the receive signal window until the receive
signal is found. The tracking window automatically sweeps
through a range of time intervals based on the minimum andmaximum expected sound speeds programmed by the user.
The window moves (tracks) in response to changes in thefluid sound speed. Once the optimal signal is found, ATW
locks onto it until another large change in sound speed
occurs. When this happens, ATW returns to the seek mode
until the optimal signal is found again.

Variable time interval
Transmit signal

Receive signal

Variable time interval
Transmit signal

Tracking window
locked onto
receive signal

Receive signal
Range of tracking window
TimeATW ensures accuracy when fluid conditions change
Tracking window
locked onto
receive signal
Range of tracking windowTime

XMT868i specifications
Operation and performance
Fluid types
Acoustically conductive fluids, including most clean liquids,
and many liquids with entrained solids or gas bubbles.
Maximum void fraction depends on transducer, interrogation
carrier frequency, path length and pipe configuration.
Pipe sizes• Clamp-on transducers: 0.5 in to 300 in(12.7 mm to 7.6 m) and larger• Wetted transducers: 1 in to 200 in(25.4 mm to 5 m) and larger
Pipe wall thickness
Up to 3 in (76.2 mm)
Pipe materials
All metals and most plastics. Consult Panametrics for concrete,composite materials, and highly corroded or lined pipes.

Display
Optional: two-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 supply• Standard: 100-240 VAC ±10%
• Optional: 12 to 28 VDC, ± 5%

Note: For DC-powered meters, Class 2 rated supplies must be used for theline power

Power consumption
20W maximum
Operating temperature-40°F to 140°F (-40°C to +60°C)

Flow accuracy (velocity)±0.5% of reading (achievable with process calibration)

Storage temperature–67°F to 167°F (–55°C to 75°C)

Typical clamp-on flow accuracy (velocity)• Pipe ID>6 in (150 mm): ±1% to 2% of readingStandard inputs/outputs
Two 0/4 to 20 mA isolated outputs, 600 S maximum loadNamur NE043 compliant

Typical wetted flow accuracy (velocity)±1% of reading

Optional inputs/outputs
All analog and digital I/O are available in specificcombinations. Consult Panametrics for available option cards.

• Pipe ID<6 in (150 mm): ±2% to 5% of reading

Accuracy depends on pipe size, installation and whether measurement is
one-path or two-path.

Repeatability±0.1% to 0.3% of reading
Range (bidirectional)–40 to 40 ft/s (–12.2 to 12.2 m/s)
Rangeability (overall)
400:1
Specifications assume a fully developed flow profile (typically 10 diameters
upstream and 5 diameters downstream of straight pipe run) and flow
velocity greater than 1 ft/s (0.3 m/s).

Measurement parameters
Volumetric flow, totalized flow and flow velocity

Electronics
Flow measurement
Patented correlation transit-time™ mode
Enclosures• Standard: Epoxy-coated aluminum weatherproof
Type 4X/IP66 Class I, Divison 1, Groups B, C & D; Class II,Groups E, F & G; Class III Flameproof II 2 GD EEx d IIC T5/T6• Optional: Stainless steel

Dimensions
Standard: Weight 10 lb (4.5 kg), size (h x d)
8.2 in x 6.6 in (208 mm x 168 mm)
Channel• Standard: One-channel• Optional: Two channels (for two pipes or two-pathaveraging)• Two additional 0/4 to 20 mA isolated outputs, 1000 W
maximum load
• Two 4 to 20 mA isolated inputs, 24-VDC loop power• Two or four isolated, three-wire RTD (temperature) inputs,–148°F to 662°F (–100°C to 350°C), 100 S platinum• Two or four pulse or frequency outputs, optically isolated,
3A maximum, 100 VDC maximum, 1W maximum, from DC to
10 kHz maximum• Alarm relays

Digital interfaces• Standard: RS232• Optional: RS485 (multiuser)• Optional: HART® protocol• Optional: Modbus® protocol• Optional: Foundation Fieldbus®
• Optional: OPC server• Optional: Ethernet
Data logging• Standard: None

• Optional: Memory capacity (linear and/or circular type) to
log up to 150,000 flow data points
European Compliance
System complies with EMC Directive 89/336/EEC, 73/23/
EEC LVD (Installation Category II, Pollution Degree 2) andtransducers comply with PED 97/23/EC for DN<25

Clamp-on ultrasonic flow transducers
Temperature range• Standard: -40°F to 302°F (-40°C to 150°C)• Optional: -328°F to 752°F (-200°C to 400°C)
See specific transducer for exact temperature range.

Mountings
Stainless steel chain or strap, welded or magnetic
clamping fixtures
Area classifications• Standard: General purpose• Optional: Weatherproof type 4X/IP66• Optional: Explosion Proof, Class I, Division 1, Groups B, C & D;
Class II, Groups E, F & G; Class III• Optional: Flameproof II 2 G EEx md IIC T6–T3• Optional: Submersible (IP68)

Wetted ultrasonic flow transducers
Temperature ranges• Standard: –40°F to 212°F (–40°C to 100°C)• Optional (overall range): –310°F to 1112°F (–190°C to 600°C)
Pressure ranges• Standard: 0 to 3000 psig (1 to 207 bar)
• Optional: Higher pressures on request

Materials• Standard: Stainless steel• Optional (for Pan-Adapta® Plugs):
Titanium, Hastelloy® alloy, Monel® alloy, duplex, CPVC, PVDFand others
Pan-Adapta plugs allow installation and removal of wetted transducers
without interrupting the process or emptying the pipe.

Process connections• Standard: 1 in or 3/8 in NPTM

• Optional: RF flanged, socket weld, fuse bond and others
Mountings
Flanged flowcell, hot tap or cold tap
Area classifications• Standard: General purpose• Optional: Weatherproof Type 4/IP65• Optional: Class I, Division 1, Groups B, C & D; Class II, Groups
E, F & G; Class III• Optional: Flameproof II 2 G EEx d IIC T6• Optional: Submersible

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™ System transducerand holder (see BWT™ System specifications)• Clamp-on extended temperature (C-ET) range
transducer system

Energy measurement
Calculates energy flow rate and totalized energy. Requires
optional RTD or analog I/O board.
Temperature transducers
Loop-powered, three-wire, platinum RTDs; clamp-on andwetted (thermo-well) types are available
Accuracy±0.15°C with wetted RTDs (matched pairs)Range-4°F to 500°F (-20C° to 260°C)
The accuracy of the energy measurement is a combination of theaccuracy of the associated flow and temperature measurements. 1% to 2%of reading is typical for calibrated systems. Not all extremes of parameters
can be achieved simultaneously.

Additional options
PanaView™ PC interface software
The DigitalFlow XMT868i communicates with a PC througha serial interface and Windows® operating systems. Consult
the manual for details on sites, logs and other operations
with a PC.

XMT868i application notes in brief.
Ultrasonic flowmeter saves money over mag meter
A sewerage/wastewater facility found that installing aPanametrics clamp-on ultrasonic flowmeter offered
excellent performance and accuracy and was far lessexpensive than installing a new mag meter. When comparing
cost of a new 30 in (750 mm) mag meter to be installed on
their cast iron line to that of a two-path Panametrics meter,
the water treatment plant decided that the ultrasonic meter
was a bargain. The 30 in (750 mm) mag required the line tobe shut down for installation and major piping work needed
to be done. It was estimated that it would take several days
to get the meter running. The Panametrics meter was easily
installed to existing piping without ever shutting down thepipe and installation was complete within a day.

710°F (376°C) Resid line? No problem.
With the DigitalFlow XMT868i combined with the Bundle
Wafeguide Technology System from Panametrics, youcan measure cryogenic fluids like LNG or the demanding
temperatures of coker resid lines that can run hotter than700°F (371°C). Ultrasonic flowmeters will not cause pressure
drop and have no impulse lines to plug, making them a greatsolution for difficult fluids.
Even though most ultrasonic manufacturers’ flowmeters
can only handle up to 500°F (260°C), Panametrics BWT
systems have been able to reach up to 1000°F (537°C).
The unique design removes the piezoelectric elementfrom the extreme temperatures by using wave guidetechnology. The transducer can even be swapped out underoperating conditions. One customer has installed 16 units,
replacing their wedge meters, and has had them operating
maintenance free for more than five years.

Bundle Waveguide Technology System

Copyright 2020 Baker Hughes Company. All rights reserved.
BHCS38689 (12/2020)

panametrics.com