The Panametrics DigitalFlow DF868 Ultrasonic Flow Meter is a full-featured, fixed-installation liquid flow meter built to meet comprehensive flow metering and energy measurement needs. Its patented Correlation Transit-Time™ digital signal processing delivers drift-free measurements in ultraclean and most "dirty" liquids, including fluids with gas bubbles and entrained solids that previously required Doppler-type meters.

The meter uses the transit-time flow measurement technique: a pair of transducers send and receive coded ultrasonic signals through the fluid. When the fluid is flowing, signal transit time in the downstream direction is shorter than in the upstream direction, and the difference between these times is proportional to the flow velocity. The DF868 measures this time difference and uses programmed pipe parameters to calculate flow rate and direction.

A standard Automatic Tracking Window (ATW) feature ensures accurate measurements even when fluid properties are unknown or changing. Like the seek mode on a car stereo, ATW dynamically sweeps the receiver window whenever the fluid’s sound speed shifts, enabling reliable measurement during temperature changes, multiproduct pipeline transfers, or other fluid property variations.

Built with fully solid-state components, the DF868 has no moving parts to wear out or orifices to clog, resulting in minimal downtime and low long-term maintenance costs.

Applications for the DF868

• Refined hydrocarbons
• Petroleum products
• Crude oil
• Lubricating oils
• Diesel and fuel oils
• Solvents
• Water and wastewater
• Hot/chilled water
• Water/glycol solutions
• Chemicals
• Other acoustically conductive liquids

Dual-Channel Version Reduces Costs and Improves Performance

The optional dual-channel/dual-path model can be user-configured for a variety of applications. It can measure flow in two separate pipes with a single meter, reducing the cost-per-measurement point. For maximum accuracy and to minimize the effects of flow profile distortions, flow swirl and cross flow, two sets of transducers can be installed on the same pipe for dual-path averaging.

Measure Flow from Outside the Pipe

Using clamp-on flow transducers, the DF868 measures flow rate through metal, plastic or even concrete-lined pipes without penetrating the pipe wall. A variety of clamping fixtures are available to hold transducers in place, accommodating different pipe sizes, transducer types and attachment methods (chain, wire rope, Velcro strap, magnetic, bolt-on or weldable steel yoke with metal band). The universal clamping fixture includes ruled slide tracks to simplify transducer spacing for accurate measurements, and a special small-pipe clamping fixture with miniaturized transducers is available for 0.5 to 2 inch lines. The meter supports pipe wall thickness up to 3in (76.2mm) for clamp-on applications.

Wetted Transducers for Maximum Accuracy

Obstructionless wetted transducers are available for maximum performance. After proper installation, transit-time accuracies of better than 1 percent are achievable in most applications, matching the performance of expensive factory-calibrated meters. The measurement range is 0.1 to 40 ft/s (0.03 to 12.2 m/s) for a turndown ratio of 400 to 1, in pipes from 1 to over 200 inches in diameter. Measurement is non-contaminating, obstruction-less and causes no pressure drop. The fully digital design ensures measurements do not drift over time.

Dual-LCD Display, Data Logger and a Wide Variety of I/O Options

All DF868 meters (single or dual-channel) feature two independent user-programmable graphic LCDs, giving simultaneous access to more data. Users can display any parameter on either LCD in a variety of numerical and graphic formats, including real-time flow values, flow graphs, diagnostic waveforms, and data from the built-in 43,000-point data logger. 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

Every DF868 includes energy measurement software as standard. With optional RTDs and input boards, it extends ultrasonic flow measurement to energy flow monitoring for water and water/glycol heating and cooling systems, with a temperature range of -4 to 410°F (-20 to 210°C). Three analog input board options are available to ensure compatibility with existing temperature instrumentation: a transmitter input board with 24-VDC loop power and two isolated 4-20mA inputs, and an RTD input board with two isolated three-wire RTD inputs for temperatures from -100 to 350°C (-148 to 662°F).

National Stock Numbers (NSN)

The following National Stock Numbers reference the Panametrics DigitalFlow DF868 Ultrasonic Flow Meter:

Features

• Supports pipe wall thickness up to 3in (76.2mm) for clamp-on applications
• ±40ft/s (±12.2m/s) bidirectional flow velocity range
• -4 to 131°F (-20 to 55°C) main unit operating temperature
• ±0.1% to 0.3% of reading repeatability
• Totalized flow and trend data logging (43,000-point built-in logger)
• Optional two-channel / two-path configuration
• Standard built-in energy measurement software (RTD/input board optional)
• Dual independent user-programmable backlit LCD displays
• NIST traceable calibration available
• Hazardous area certification available
• Patented Correlation Transit-Time™ digital signal processing for drift-free measurement
• Standard Automatic Tracking Window (ATW) for stable measurement with changing fluid properties
• No moving parts, no pressure drop, low long-term maintenance cost