DigitalFlow™
DF868

Panametrics liquid
ultrasonic flowmeter
Applications

Features

The DF868 liquid flowmeter is a complete ultrasonic flow
metering system for measurement of:• Economical non-intrusive flow measurement• Water and wastewater• Hot/chilled water• Water/glycol solutions• Refined hydrocarbons• Petroleum products• Crude oil• Lubricating oils
• Diesel and fuel oils
• Solvents• Chemicals• Other liquids• Hazardous (classified) location certifications• Simple set-up and installation• Suitable for wide range of pipe sizes and materials• Two-channel/two-path version available

Panametrics ultrasonic liquid flowmeter
The DigitalFlow DF868 is a full-featured, fixed-installation
liquid flowmeter designed to meet all your flow meteringand energy measurement needs. Its patented Correlation
Transit-Time™ digital signal processing provides drift-freemeasurements in ultraclean and most “dirty” liquids. This
includes fluids with gas bubbles and entrained solids thathave previously required Doppler-type meters.

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. To minimize the effectsof flow profile distortions, flow swirl and cross flow, and toprovide maximum accuracy, two sets of transducers can beinstalled on the same pipe.

Measure flow from outside the pipe
Using clamp-on flow transducers, the DigitalFlow DF868
measures flow rate through metal, plastic or even concretelined pipes without penetrating the pipe wall. To hold clampon transducers in place, a variety of clamping fixtures areavailable to accommodate different pipe sizes, transducer
types and attachment methods (e.g., chain, wire rope,Velcro® strap or a magnetic, bolt-on, or weldable steel yokewith metal band). Our universal clamping fixture includes
ruled slide tracks to simplify transducer spacing for accurate
flow measurements. There’s even a special small-pipe
clamping fixture with miniaturized transducers to simplify
flow measurement on 0.5 to 2 inch (15 to 50 mm) lines.

Wetted transducers for maximum accuracy
Obstructionless wetted transducers are readily available for
maximum performance. After proper installation, transittime accuracies of better than 1 percent are achievable inmost applications, matching the performance of expensive
factory-calibrated meters. Measurement range is 0.1 to40 ft/s (0.03 to 12.2 m/s) for a turndown ratio of 400 to 1 inpipes from 1 to over 200 inches in diameter. Measurement isnoncontaminating, obstructionless and causes no pressure
drop. The DigitalFlow DF868 is all digital so measurements
don’t drift, and it doesn’t need regular maintenance since
there are no moving parts to wear out or orifices to clog.

Dual-LCD display, datalogger and a wide
variety of I/O options
Whether single-channel or dual-channel, all DF868 meters
feature two independent, user-programmable, graphicLCDs, giving you simultaneous access to more data. There iscomplete flexibility to display any parameter on either LCD ina variety of numerical and graphic formats. Examples include
numerical display of real time flow measurements, real timeflow graphs and diagnostic waveforms, and numerical/graphic display of data from the meter’s built-in 43,000 pointdatalogger. Up to 12 isolated 4 to 20 mA outputs, up to six
hermetically sealed or standard alarm relays, and up to 12
frequency/totalizer outputs can be added.

Built-in energy measurement capability
Another feature that makes the DigitalFlow DF868 metersuch a powerful and versatile flowmeter, is the energy
measurement software included in every meter. The
DigitalFlow DF868, with optional RTDs and input boards,
extends the benefits of ultrasonic flow measurement toenergy measurement. Benefits include measurement of flow
and temperature without pipe penetration, and compatibility
with pipes from 1 to 200 in (25.4 mm to 5 m) in diameter. TheDigitalFlow DF868 meter measures energy flow in water andwater/glycol heating and cooling systems with temperaturesfrom -4°F to 410°F (-20°C to 210°C). Consult Panametrics foruse with other liquid systems.
To ensure compatibility with existing or preferredtemperature instrumentation, the DigitalFlow DF868 meter isavailable with three analog input boards. The analog input
board provides 24 VDC loop power and two isolated 4 to 20mA inputs for transmitters. For applications requiring directRTDs, the RTD input board provides two isolated, three-wire
RTD inputs for temperatures from -148°F to 662°F (-100°C to350°C).

Flowmeter transducers

The DF868 flowmeter uses the transit-time flow
measurement technique
The transit-time technique uses a pair of transducers, with
Fluid flow sending and receiving coded ultrasoniceach transducer
signals through the fluid. When the fluid is flowing, signaltransit time in the downstream direction is shorter thanin the upstream direction. The difference between these
Ultrasonic signal pathtransit times is proportional
to the velocity of the flow. TheDigitalFlow DF868 measures this time difference and uses
programmed pipe parameters to determine flow rate anddirection.
Flowmeter transducers

Fluid flow

Ultrasonic signal path
Transit-time flow measurement technique

Automatically adjusts to changing
fluid properties
Our unique Automatic Tracking Window™ (ATW™) feature,
standard in all DigitalFlow DF868 meters, ensures accurate
flow measurements even when fluid properties are unknownor changing. Like the seek mode on a car stereo, ATW
dynamically sweeps the receiver window whenever thesound speed of the fluid changes. This powerful featureenables flow measurement when the fluid sound speed
is unknown, when it is changing due to large temperature
shifts, or when a new liquid starts to flow in a multiproductpipeline.
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

TimeTracking window
locked onto
receive signal
Range of tracking window
ATW ensures accuracy when fluid conditions change

Is built to be economical and stay economical
To be of real value, a flowmeter must be as economical to
Variable time interval
own and operate as it is capable in the field. Using the latest
Transmit signal
Receivesignal
microcircuitand manufacturing
technologies,
the DigitalFlow
TimeDF868 flowmeter is built to stay in service for many years.
Completely solid state, the DigitalFlow DF868 rarely wears
out or needs servicing, resulting
in little
downtime and low
Tracking
window
locked onto
maintenance costs.
receive signal

The DigitalFlow DF868 will continue to save money by
Range of tracking window
streamlining the measurement process and trimming laborcosts.

DF868 specifications
Operation and performance

ChannelFluid types
Acoustically conductive fluids, including most cleanliquids, and many liquids with entrained solids or gas
bubbles. (Maximum void fraction depends on transducer,
interrogation carrier frequency, path length and pipe
configuration.)• Standard: One-channel

Pipe sizes• Using clamp-on transducers: 0.5 to 300 in(12.7 mm to 7.6 m) and larger

Keypad39-key tactile feedback membrane keypad• Using wetted transducers: 1 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.
Flow accuracy (velocity)±0.5% of reading (achievable with process calibration)
Typical clamp-on flow accuracy (velocity)• Pipe ID>6 in (150 mm): ±1% to 2% of reading• Pipe ID<6 in (150 mm): ±2% to 5% of reading
Typical wetted flow accuracy (velocity)±1% 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

• Optional: Two channels (for two pipes or two-pathaveraging)
Display
Two independent software-configurable 64- x 128-pixelbacklit LCD graphic displays

Power supply• Standard: 100 to 130 VAC, 50/60 Hz or
200 to 265 VAC, 50/60 Hz• Optional: 12 to 28 VDC, ±5%Note: For DC-powered meters, Class 2 rated supplies must be used for theline power

Power consumption
20 W 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/outputs
Two 0/4 to 20 mA isolated outputs, 550 W maximum loadNamur NE043 compliant
Optional inputs/outputs
There are six 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,
1000 W maximum load

• Analog inputs: Select up to three boards of one of thefollowing types:­ - Analog input board with two isolated 4 to 20 mA inputs
and 24 V loop power­ - RTD input board with two isolated, three-wire, RTD inputs;
span -148°F to 662°F (-100°C to 350°C); 100 W• Totalizer/frequency outputs: Select up to three totalizer/
frequency output boards, each with four outputs per board,
10 kHz maximum. All boards allow software-selectablefunctioning in two modes:

Enclosures­ - Totalizer mode: Pulse per defined unit of parameter (e.g.,1 pulse/gal)• Optional: Stainless steel, fiberglass,explosion-proof, flameproof• Alarm relays: Select up to two boards of one of thefollowing types:• Standard: Epoxy-coated aluminum weatherproof Type 4X/
IP66 Class I, Division 2, Groups A,B,C&D

Dimensions (standard)• Weight 11 lb (5 kg),

• Size (h x w x d) 14.24 in x 11.4 in x 5.1 in(362 mm x 290 mm x 130 mm)­ - Frequency mode: Pulse frequency proportional tomagnitude of parameter (e.g., 10 Hz = 1 gpm)

­ - General purpose: Relay board with three Form C relays;
120 VAC, 28 VDC maximum, 5 A maximum; DC 30 Wmaximum, AC 60 VA­ - Hermetically sealed: Relay board with three hermeticallysealed Form C relays; 120 VAC, 28 VDC maximum, 2 Amaximum; DC 56 W maximum, AC 60 VA

Digital interfaces• Standard: RS232Mountings
Flanged flowcell, hot tap or cold tap• Optional: RS485 (multiuser)• Optional: Modbus® RTU

Area classifications• Standard: General purpose• Optional: Weatherproof type 4/IP65• Optional: Modbus TCP• Optional: Explosion-proof Class I, Division 1, Groups C&D;
Class II, Groups E,F&G; Class III• Optional: OPC server• Optional: Ethernet

Site parameter programming• Menu-driven operator interface using keypad and “soft”
function keys
• Storage for 10 sites• Optional: Flameproof ( II 2 G Ex d IIC T6)• Optional: Submersible

MCerts Product Conformity Certificate
Sira MC 050061/00 for continuous water monitoring (EU IPPC)

Data logging
Memory capacity (linear and/or circular type) to log over
43,000 flow data points

Transducer cables

Display functions• Graphic display shows flow in numerical or graphic format• Optional: Lengths up to 1,000 ft (330 m) maximum• Displays logged data and diagnostics

European compliance
Complies with EMC Directive 2004/108/EC, 2006/95/EC LVD(Installation Category II, Pollution Degree 2)

Clamp-on ultrasonic flow transducers
Temperature ranges• 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• Optional: Submersible

II 2 G Ex md IIC T6–T3

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)

• Standard: One pair of coaxial cables, type RG62 AU, or as
specified for transducer typeHigh-temperature and high-pressure ultrasonicflow transducers• Bundle Waveguide Technology™ System transducer
and holder (see BWT™ System specifications)

Energy Measurement

Calculates energy flow rate and totalized energy usage.
Requires optional RTD or analog inputs to the DF868 with
two temperature inputs: one for supply and one for returntemperature. Typical installations use surface mount RTDs
with integrated 4-20 mA transmitters, but wetted RTDs withthermowells are available if more accuracy is required and if
the line can be shut down for installation.

Surface mount RTDs

Pt 1000, 4-wire, matched pair with integrated 4-20 mA
transmitters
Range• 0° to 50°C (32° to 122°F)• 0° to 150°C (32° to 302°F)• Field configurable to special ranges
Accuracy±0.12°C of temperature @ 0°C

Thermowell RTDs

Pt 100, 1/10 DIN, 3 wire, matched pair
Range
• Direct RTD Input• Optional: Higher pressures on request­ - Configurable in DF868. Maximum range -100° to 350°C(-148° to 662°F)

Materials• Standard: Stainless steel­ - 0° to 50°C (32°F to 122°F)• Integrated 4-20 mA transmitter• Optional (for Pan-Adapta® Plugs):
Titanium, Hastelloy® alloy, Monel® alloy, duplex,­ - 0° to 100°C (32°F to 212°F)

Pan-Adapta plugs allow installation and removal of wetted transducers
without interrupting the process or emptying the pipe.

Accuracy±0.15°C

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

• Optional: RF flanged, socket weld, fuse bond and others­ - -50° to 200°C (-58° to 392°F)

Additional options
PanaView™ PC interface software
The DigitalFlow DF868 communicates with a PC through aserial interface and Windows® operating systems. Consult
the manual for details on sites, logs and other operations
with a PC.

Panametrics, a Baker Hughes business, provides solutions in
the toughest applications and environments for moisture,oxygen, liquid and gas flow measurement.
Experts in flare management, Panametrics technology also
reduces flare emissions 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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