Greyline Instruments Inc.

- Model TTFM 1.0 - Transit Time Flowmeter for Clean Liquids



Accurately measure the flow rate of clean, non-aerated liquids like water, chemicals, and oils in full pipes. Ultrasonic transducers mount on the outside of a pipe without shutting down flow. Flow rate is displayed on the large, backlit display along with totalizer and signal strength. Use the built-in control relays for flow alarms or flow proportionate pulse. Connect the isolated 4-20mA output to PLC's or controllers.


The TTFM 1.0 works on a wide range of pipe sizes and materials including carbon steel, stainless steel, ductile iron, cast iron, PVC, PVDF, fiberglass, copper, brass, aluminum and pipes with bonded liners including epoxy, rubber and Teflon.

The TTFM 1.0 Transit Time Flowmeter operates by measuring the “transit time” or “time of flight” for ultrasonic sound pulses transmitted from one transducer to another. Depending on the mounting configuration, the signal may cross the pipe once, twice or four times. To measure flow the transit time is compared between ultrasonic signals travelling upstream and downstream.

  • Non-Contacting Clamp-on Ultrasonic Transducers
  • Works on Metal and Plastic Pipes
  • Large Backlit Flow Rate Display and Totalizer
  • Isolated 4-20mA Output
  • Built-in 5-Key Calibrator
  • 2 Programmable Control Relays
  • Optional 20 Million Point Data Logger

  • pair SE16B ultrasonic transducers - clamp-on for 1/2” to 24” (12 mm to 610 mm) pipes
  • sensor cables - pair 25 ft / 7.6 m coaxial with BNC connectors
  • flow rate range: ± 0.07 to 39 ft/sec (± 0.02 to 12 m/sec)
  • installation - stainless steel transducer mounting brackets and clamps, alignment bar and silicone coupling compound kit
  • enclosure - watertight, NEMA4X (IP66) polyester and polycarbonate
  • display - white, backlit matrix
  • totalizer - 14 digits
  • calibration - built-in 5-key programmer
  • output - isolated 4-20mA (1000 ohm)
  • 2 control relays - 5 amp, SPDT - programmable for flow proportional pulse output, and/or flow alarm
  • plug-and-play options including data logger and extra control relays
  • power input - 100-240VAC 50/60Hz, 4 Watts maximum
  • electrical surge protection and RFI filters - AC, sensor, 4-20mA


The TTFM 1.0 Transit Time Flowmeter works by measuring the 'transit time' or 'time of flight' for ultrasonic sound pulses transmitted from one transducer to another. Depending on the mounting configuration, the signal may cross the pipe once, twice or four times. The time between transmitted and received signals is precisely measured by the flow meter. Ultrasonic signals are sent upstream and then downstream with the transducers alternating their functions as transmitters/receivers.

The transit time in the direction of flow is always faster than the transit time against the flow. By comparing these differences with precision timing circuits, the TTFM 1.0 is able to accurately calculate the flow rate. Because the ultrasonic signal is forced to cross the pipe, an average of the flow profile is calculated. So compensation for laminar or turbulent flow is automatic.

TTFM 1.0 transducers can be mounted on vertical or horizontal pipes. The pipe must be full. Choice of V, Zor W mounting method depends on the application and pipe diameter. V-Mount is the most common method while Z-Mount is used for larger pipes or weak signal applications and W-Mount for smaller pipes.


The TTFM 1.0 Transit Time Flowmeter is designed for flow measurement of clean, non-aerated liquids in full pipes. High concentrations of solids or gas bubbles (>2% by volume) will attenuate sound and the Transit Time ultrasonic signal may not be able to cross the pipe. A Greyline Doppler-type flow meter is recommended for applications with solids or bubbles (eg. wastewater or slurries).

Works from the Outside of Common Pipe Materials
Mount the TTFM 1.0 ultrasonic transducers on the outside of metal or plastic pipes including carbon steel, stainless steel, ductile iron, cast iron, PVC, PVDF, fiberglass, copper, brass, aluminum and pipes with bonded liners including epoxy, rubber and Teflon. Avoid pipes made with porous materials (e.g. wood or concrete) or with loose insertion liners.

Simple Menu System for Fast, Easy Start-up and Calibration
Calibration and start-up can be done in a few minutes. Use the built-in 5-button keypad to enter the pipe material and OD, wall thickness and fluid type. The TTFM 1.0 will display the correct transducer separation distance and mounting method. Secure the stainless steel pipe clamps and align the mounting brackets on the outside of the pipe. Put coupling compound (included) on the transducer faces and insert them into the mounting brackets. The TTFM 1.0 will immediately begin to display, transmit and totalize flow.


The TTFM 1.0 Transit Time Flowmeter transducers are rated for accidental submersion up to 10 psi (0.75 bar). The flowmeter will continue to operate and measure flow accurately during periods of submergence. Plastic seal jackets on the cables can be filled with coupling compound to provide additional moisture protection for the BNC cable connectors.

General Specifications: Greyline TTFM 1.0 Ultrasonic Transit Time Flow Meter

  • Operating Parameters: For clean liquids in full pipes with less than 2% solids or gas bubbles
  • Calibration: Built-in 5-key calibrator with English, French Spanish language selection
  • Electronics Enclosure: Watertight and dust tight NEMA4X (IP 66) polycarbonate with clear, shatterproof cover
  • Accuracy: ± of reading or 0.1 ft/sec (0.03 m/sec), whichever is greater 1% Repeatability & Linearity: ±0.25%
  • Display: White, backlit matrix - displays ,14-digit totalizer, relay 5-digit flow rate with floating decimal status, operating mode and calibration menu
  • Power Input: 100-240VAC 50-60Hz (see Options), Watts maximum (with standard features) 4.0
  • Output: Isolated 4-20mA/0-5V, 1000 ohm load maximum, programmable offset
  • Control Relays: 2 programmable flow alarm and/or flow Relays, form 'C' dry contacts rated 5 amp SPDT; proportional pulse
  • Operating Temp. (electronics): -5° to 140°F (-20° to 60°C)
  • Approximate Shipping Weight: 1 lbs. ( .5 kg)

Transducer Specifications

  • Pipe Diameter: ½ to 48” (12 mm to 1200 ) ” mm
  • Pipe Materials: Any metal or plastic sonic conducting material including carbon steel, stainless steel, ductile iron, cast iron, , aluminum PVC, PVDF, fiberglass, copper, brass and pipes with bonded liners including epoxy, rubber and Teflon
  • Flow Velocity: ± 0.07 to 39 ft/sec ( 0.02 to 12 m/sec)
  • Operating Frequency: 1.28 MHz
  • Operating Temperature: -40° to 300°F (-40° to 150°C)
  • Transducer Mounting Kit: Includes set of stainless steel pipe clamps, and coupling compound alignment bar
  • Transducer Cables: RG-58 coaxial, 25 ft (7.6 m) with BNC connectors and seal jackets
  • Certification: Non-incendive for Class I Division 2, Groups A,B,C,D hazardous locations

Popular Options

  • Transducer Cables: 50 ft (15 m) coaxial with BNC connectors and seal jackets or splice up to 0 ft ( m) shielded coaxial NEMA4X (IP66) 25 75 with Junction Box
  • Power Input: 9-3 VDC 2
  • Control Relays: 4 additional (6 total), rated 5 amp SPDT
  • Enclosure Heater: Thermostatically controlled - recommended for temperatures below 32°F (0°C)
  • Sunscreen: Enclosure sunscreen for outdoor installations
  • Data Logger: Built-in 2-million point logger with USB output and Windows software

  • Potable water
  • River water
  • Cooling water
  • Demineralized water
  • Water/glycol solutions
  • Hydraulic oil
  • Diesel and fuel oils
  • Chemicals

Install the TTFM 1.0 Transit Time Flowmeter without cutting the pipe or shutting down flow. It operates on a wide range of metal and plastic pipe sizes and takes just a few minutes to calibrate and start-up.

The flowmeter works by injecting sound through the pipe wall and into the flowing liquid. The transducers transmit ultrasonic signals back and forth. The up and downstream 'transit times' are precisely measured and compared to calculate the flow rate. Advanced signal processing software and electronics suppress interference and measure flow with high repeatability and accuracy.


Plug-and-play options including a 2-million point data logger and extra control relays can be installed at any time. Power consumption is low (4 Watts typical) with standard AC and optional DC power input. Display backlight brightness is adjustable and 4-20mA output and relays can be disabled to reduce power consumption.

The TTFM ultrasonic transducers are waterproof and designed to operate in wet environments or during accidental submersion. Transducer cable length can be field- extended up to 250 ft (75 m) with optional shielded cable and junction box.

SCOPE: This specification covers an Transit Time Ultrasonic Flow Meter as manufactured by Greyline Instruments, Massena, New York / Long Sault, Ontario. The instrument shall provide for non-intrusive flow measurement, indication, totalizing and transmitting of the flow rate in a full pipe.

Performance Specifications

  1. The ultrasonic flow meter shall have an accuracy of ±1% of flow rate in clean fluid applications depending on pipe size and flow regime. Have repeatability and linearity of ±0.25%.
  2. Shall operate on clean liquids in full pipes with less than 2% solids or gas bubbles at flow velocities from ±0.07 to 39 ft/sec (±0.02 to 12 m/sec).
  3. Operate on the following pipe materials: carbon steel, stainless steel, PVC, PVDF, fiberglass, galvanized steel, mild steel, glass, copper, brass and pipes with bonded liners including epoxy, rubber and Teflon.

Transducers (Flow Sensors)

  1. The flow meter shall have a dual transmitting/receiving, clamp-on transducers. The transducers shall be waterproof and operate continuously at temperatures from -40°F to 300°F (-40°C to 150°C).
  2. The standard transducer pair shall be designed to install on pipes with inside diameter ranging from 1/2' to 24' (12 mm to 610 mm).
  3. Have 25 ft (7.6 m) length coaxial cables from the electronics with BNC connectors to transducers.
  4. Shall include manufacturer's recommended sensor coupling compound. Shall include stainless steel mounting hardware with pipe clamps.
  5. Shall include BNC seal jackets for transducer operation in wet or submerged conditions.


  1. The transmitter indicator shall be housed in a watertight and dust tight NEMA4X (IP 66) polyester and polycarbonate enclosure with a gasketed shatter proof window, and suitable for wall mounting.
  2. Flow meter electronics shall be designed to operate at temperatures from -5°F to 140°F (-20°C to 60°C). Electronic circuits are interchangeable with other flow meters having the same model number. The transmitter circuit and calibration frequency standard shall be crystal controlled. The transmitter shall be powered by 100-240VAC 50/60Hz requiring less than 4 Watts.
  3. The transmitter shall include a built-in 5-Key calibration system with operator selection of parameters through visual prompts from a Menu calibration system. Systems requiring calibration by Parameter codes or external calibrators shall not be accepted.
  4. The 4-20mA shall be flow proportional and isolated, with programmable zero and full scale offsets. Maximum resistive load shall be 1000 ohms. It shall include automatic high voltage bleeds for nearby lightning strikes.
  5. Shall include noise suppression circuitry to filter electrical interference.
  6. Have a white, backlit matrix LCD display indicating flow rate in user-selected engineering units, units of calibration, relay states, signal strength and 14-digit totalizer.
  7. Have 2 control relays rated 5 ampere SPDT. Relays shall be programmable for flow proportional pulse output, or as flow rate alarms with separate ON/OFF set points.
  8. Shall display and totalize forward and reverse flow.
  9. Electronics shall be modular and field replaceable by means of plug-in circuit boards. The instrument shall detect and load software menus automatically for field-installed options.

Additional Features For Insertion In Specification As Required:

  1. Transducer cables shall be 50 ft (15m) length coaxial with BNC transducer connections.
  2. Transducer cable shall be extended length shielded coaxial pair up to 250 ft (75 m) with NEMA4X (IP 66) Junction Box.
  3. Have a thermostatically controlled AC-powered enclosure heater for condensation protection in locations with temperature below -5°F (-20°C).
  4. Have power input of 9-32VDC.
  5. Have 4 additional (6 total) control relays, rated 5 amp SPDT and programmable for flow rate alarms or flow totalizer pulse.
  6. Have a built-in 2 million point Data Logger with USB output to flash drive or mass storage device. Include Windows software.


The instrument shall be a Model TTFM 1.0 Transit Time Flowmeter as manufactured by Greyline Instruments Inc., and warranted against defects in materials and workmanship for one year.

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