CTF878 Clamp On Gas Meter

  • Only flowmeter worldwide to measure low pressure flows (<5 bar) Worldwide support/installation by experienced engineers
  • No Downtime - minimal installation costs Wide range of applications including natural gas, corrosive/toxic gases, low pressure
  • Correlation Tag Technology Unique technology providing accuracies of +/-1 to 2% of rate. AGA compliant
  • Sales, Rental & Installation
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The DigitalFlow CTF878 Correlation Tag Clamp-on Gas Ultrasonic Flowmeter is suitable for metal pipes and for pressure as low as atmospheric. It is non-invasive, has no wetted parts or moving parts. There is therefore no process down time or significant installation costs for this clamp on technology.

The CTF878 uses a new technology called correlation tag, to determine the flow rate of gases. This is like no other clamp on gas flowmeters. The CTF878 flow meter is supplied with two pairs of ultrasonic transducers - the first measure the upstream disturbance, and the second (situated downstream) record the downstream disturbance. The flow meter constantly samples these traces and correlates the two traces. When the flow meter recognises that the same disturbance pattern has travelled along the pipe, it is possible to measure the velocity. This is done constantly every second. Each pair of transducers includes a transmitter sending ultrasound in a continuous wave mode through the fluid to the receiver, forming an upstream and downstream interrogation path. The continuous wave signal is modulated by turbulence and local density variations that are characteristic of a moving gas.

In the past, a restricting factor in gas measurement has been the signal strength of transducers: having to send an ultrasonic signal through the metal pipe wall, through the gas, and then back through the pipe wall again. New clamp-on gas transducers produce signals that are five to ten times more powerful than signals of traditional ultrasonic transducers. This new technology produces clean, strong signals with marginal background noise.

Specifications assume a fully developed flow profile (typically 20 diameters upstream and 10 diameters downstream of straight pipe run).

Manufactured by: Panametrics
Model: CTF878 Clamp On Gas Meter

Services offered for this product

  • Sales
  • Rental
  • Installation
  • Calibration
  • Maintenance


Natural gas
Compressed air
Low Pressure Applications
Fuel gases
Corrosive gases
Toxic gases
High-purity gases
Air separation gases
Speciality gases


Operation and performance
Fluid types All acoustically conductive gases. Minimum gas density: 0.074 lb/ft3 (1.2 kg/m3). Gas not be wet or saturated with moisture.
Pipe sizes 2 to 36 in. NB ANSI (50 to 900 mm DN)
Pipe materials Most metals and plastics. No lined pipes
Flow accuracy (velocity) ±2% of reading
Repeatability ±0.2% to 0.6%
Range (bi-directional) ±10 to ±200 ft/s (2 to 2.5 in./50 to 60 mm pipe size)
±7 to ±200 ft/s (3 to 3.5 in./80 mm to 90 mm pipe size)
±5 to ±200 ft/s (4 to 5 in./100 to 125 mm pipe size)
±3.5 to ±200 ft/s (6 to 36 in. or 150 to 900 mm pipe size)
Gas type and minimum pressure Dry air, oxygen, nitrogen or argon: ≥14.5 psia (1 bara) Sweet natural gas: ≥25 psia (1.7 bara)
Measurement parameters Velocity, actual and standard (ideal gas) volumetric flow, and totalized flow
Flow measurement Correlation tag technique
  • Standard: Epoxy-coated aluminum
  • Optional: Stainless steel
Dimensions (h x w x d) 362 x 290 x 130 mm (14.24 x 11.4 x 5.12 in)
Weight 5 kg (11 lb)
Channel Single channel
Display 240 x 200 pixel backlit LCD graphic display
Keypad 24-key rubberized tactile membrane
Power supply 85 to 264 VAC, 50/60 Hz (standard)
Operating temperature –10 to 55°C (14 to 131°F)
Storage temperature –40 to 70°C (–40 to 158°F)
Standard inputs/outputs Two 0/4 to 20 mA isolated outputs, 550 Ω maximum load
Optional inputs/outputs

There are six additional slots available for any combination of the following I/O boards:

  • Analog outputs: select additional output boards, with four isolated 0/4 to 20 mA outputs, 1 kΩ maximum load
  • Analog inputs: select one of the following:
    • 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 to 662°F (–100 to 350°C); 100 Ω Pt
    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 to 662°F (–100 to 350°C); 100 Ω Pt
  • Totalizer/frequency outputs: select output boards, with four outputs, software-selectable functioning in two modes:
    • Totalizer mode: pulse per defined unit of parameter (e.g., 1 pulse/ft3)
    • Frequency mode: pulse frequency proportional to magnitude of parameter (e.g., 10 Hz = 1 ft3/h), 10 kHz maximum
  • Alarm relays: select one of the following:
    • General purpose: relay board with three Form C relays
    • Hermetically sealed: relay board with three hermetically sealed Form C relays
Digital interfaces Standard: RS232
Optional: RS485 (multiuser)
Data logging Memory capacity (linear and/or circular type) to log over 6900 flow data points
Display functions

Graphic display shows flow in numerical or graphic format
Displays logged data and diagnostics

European compliance
  • 2014/30/EU EMC Directive
  • 2014/35/EU LVD Directive (Installation Category II, Pollution Degree 2)


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