Fox Thermal Model FT3 Thermal Gas Mass Flow Meter

Model FT3 Award Winner

The Model FT3 was designed with our oil and gas customers in mind. This meter is Quad O (OOOO) compliant and is perfect for use in flare gas applications along with other fuel gas measurement.

Key Features:

  • Insertion, Inline & Remote Styles
  • Modbus or HART options
  • Calibration Validation
  • FM/FMc, ATEX and IECEx approvals
  • Scroll down for more features/benefits!

Applications:


The free FT3 View™ software from Fox Thermal is a great way to access the meter settings directly by connecting the FT3 to a PC or laptop using a USB cable. View or change the meter settings with a simple click of the mouse. The FT3 software offers:

  • Quick access to all configuration parameters using pop-up windows and pull down menus
  • Selection of measurement units, flow and temperature ranges, alarm settings, and more
  • CAL-V™ Calibration Validation Certificate
  • Zero CAL-CHECK® Calibration Validation Certificate
  • Data Logging to a Microsoft® Excel spreadsheet
  • Display of alarm codes
  • Storage of meter configurations to a file that can be archived
  • View raw data that can be used to diagnose or troubleshoot your meter

Note: For FT3 View™ software to function properly, please be sure to have a working version of Microsoft® Office installed on the PC before installing FT3 View™.

USB Driver and the Fox Thermal FT3 View™ Software
A USB driver is needed for FT3 View™ to run. If the USB drive does not install automatically, you will need to download it by following this link. Instructions are included on how to install it correctly.


The CAL-V™ and Zero CAL-CHECK® tests are used for Calibration Validation on the Model FT3. These tests do the following:

  • Tests the functionality of the sensor and its associated signal processing circuitry
  • Checks for build-up on sensor that could affect calibration
  • Ensures that the meter still retains its original NIST-traceable calibration at zero flow
  • Checks thermal conductivity (heat transfer) repeatability of the sensor

Use this test according to the manufacturer’s instructions in order to validate the calibration of the meter.


Flow meter accuracy is often dependent on achieving a uniform flow profile near the center of the pipe. Distortion and swirl are disturbances in flow that can be remedied either by extending the length of space between the cause of the disturbance and the sensing element (increasing straight pipe runs) or by adding a flow conditioner to correct the disturbance. Flow conditioners installed upstream of flow meters reduce the need for long, straight pipe runs. Common Features for Fox Thermal FC20 Flow Conditioner:

  • For use with all Fox insertion style flow meters
  • Reduces the need for long straight pipe runs
  • Negigible pressure drop
  • Precision, laser-cut design
  • 316 stainless steel material

More Info

Common Features for Fox Thermal Model FT3 Flow Meter:

  • Measures process gas flow rate/total and temperature
  • A USB connection is standard (free FT3 View™ Software); Optional HART and Modbus RTU (RS485) communication protocols
  • Optional on-board display and configuration panel
  • Equipped with the PowerPro™ thermal mass flow sensor
  • One discrete output is programmable for either pulse (for totalizing flows) or alarms
  • One discrete input to reset total or select a different calibration on 2 gas curves
  • 4-20mA output proportional to mass flow rate
  • Click the Approvals tab for Model FT3 Agency Approvals.
  • Calibration Validation with the CAL-V™ and Zero CAL-CHECK® features.
  • NIST-traceable calibration
  • Wide measurement range
  • 1% R + 0.2% FS flow accuracy
  • 24 VDC or optional 100 to 240VAC in local or remote enclosures

FT3 Flow Meter Specs

Technical Specifications
Fox Thermal Model FT3 Thermal Mass Flow Meter & Temperature Transmitter
Performance Specs
Type Insertion Inline
Flow Accuracy: ± 1% of reading ± 0.2% of full scale.
15 diameters of straight, unobstructed pipe upstream and 10 downstream.		 ± 1% of reading ± 0.2% of full scale.
8 diameters of straight, unobstructed pipe upstream and 4 downstream.
Flow Repeatability: ± 0.2% of full scale
Flow Response Time: 0.9 seconds (one time constant)
Temperature Accuracy: ± 1.8°F (± 1.0°C) -40 to 250°F (-40 to 121°C); ± 3.6°F (± 2.0°C), 250 to 650°F (121 to 343°C); 60 SFPM minimum.
Calibration: Factory Calibration to NIST-traceable standards
CAL-V™ and Zero CAL-CHECK®: In situ, operator-initiated calibration validation
Operating Specs
Type Insertion Inline
Flow Units (field selectable): SCFM, SCFH, NMPS, NM3/M, NM3/H, NM3/D, NLPS, NLPM, NLPH, MCFD, MSCFD, SCFD, MMSCFD, MMSCFM, SMPS, SM3/H, LB/S, LB/M, LB/H, LB/D, KG/S, KG/M, KG/H, SLPM, SFPM, MT/H, SM3/M
Flow Rates: 15 to 60,000 SFPM (0.07 to 280 NMPS) - Air at 70°F (20°C) & 1 ATM
Turndown: up to 1000:1; 100:1 typical
Flow Ranges:
Pipe Size SCFM NM³/Hr
1.5" (40mm) 0 - 840 0 - 1,325
2" (50mm) 0 - 1,400 0 - 2,210
2.5" (63mm) 0 - 2,000 0 - 3,150
3" (80mm) 0 - 3,100 0 - 4,890
4" (100mm) 0 - 5,300 0 - 8,360
6" (150mm) 0 - 12,000 0 - 18,930
8" (200mm) 0 - 20,840 0 - 32,870
10" (250mm) 0 - 32,800 0 - 51,740
12" (300mm) 0 - 46,600 0 - 73,500
Pipe Size SCFM NM³/Hr
0.5" 0 - 125 0 - 200
0.75" 0 - 220 0 - 350
1" 0 - 360 0 - 570
1.25" 0 - 625 0 - 990
1.5" 0 - 840 0 - 1,325
2" 0 - 1,400 0 - 2,210
2.5" 0 - 2,000 0 - 3,150
3" 0 - 3,100 0 - 4,890
4" 0 - 5,300 0 - 8,360
6" 0 - 12,000 0 - 18,930
Note: Standard conditions of air at 70°F and one atmosphere.
Consult factory for other gases, pipe sizes, and flow ranges other than those listed.
Gas Pressure (max): 500 psig (34.5 barg) 316 SS inline w/NPT ends: 500 psig (34.5 barg)
316 SS inline w/150lb flanges: 230 psig (16 barg)
CS inline w/NPT ends: 500 psig (34.5 barg)
CS inline w/150lb flanges: 285 psig (20 barg)
Check with factory for higher pressure options.
Note: Pressure ratings stated for temperature of 100°F (38°C).
Relative Humidity: 90% RH maximum; non-condensing
Temperature by Sensor Type: (see Approvals tab) ST Sensor: -40 to 250°F (-40 to 121°C)
HT Sensor: -40 to 650°F (-40 to 343°C)
Temperature by Enclosure: (see Approvals tab) Without display or AC power supply: -40 to 158°F (-40 to 70°C)
With display and/or AC power supply: -4 to 158°F (-20 to 70°C)
Remote sensor junction box: -40 to 212°F (-40 to 100°C)
Input Power:
  • 24 VDC (±10%), 0.7 Amps (standard DC Power)
  • 100 to 240VAC ∼(+10%-15%), 50-60Hz, 0.2 Amps (with AC power option).
Note: Fluctuations of AC and DC power supply are not to exceed ±10% of rating.
Class I Equipment (Electrical Grounding Required for Safety).
Installation (Over-voltage) Category II for transient over-voltages.
Inputs/Outputs:
  • All outputs and communication circuits are galvanically isolated.
  • 4-20mA output one is proportional to the measured flow rate.
  • Fault indication per NAMUR NE43.
  • 4-20mA output two is programmable for temperature or flow rate.
  • Digital output one is programmable for either pulse (for totalizing flow) or alarms.
  • Output is open collector type, operating voltage 5V to 24V, maximum sinking current: 20mA.
  • The pulse output is proportional to flow rate with a range of 0 to 100Hz.
  • When configured for alarm, the digital output generates an on or off signal.
  • Remote switch input can be configured to reset elapsed time, flow totalizer or switch between gas curves when the 2 gas curve option is ordered.
Port: Mini USB communication port is standard.
Software: The free PC-based software tool - FT3 View™ - provides complete configuration, remote process monitoring, and data logging functions.
Optional serial communication: HART or Modbus RTU (RS485).
4-20mA Loop Verification: Simulation mode used to align 4-20mA output with the input to customer’s PLC/DCS.
Physical Specs
Type Insertion Inline
Sensor Material: 316 stainless steel standard. Hastelloy C276 optional.
Enclosure: NEMA 4X (IP68), Aluminum, dual conduit entries with ¾" NPT or optional M20 x 1.5mm.
Cabling to remote enclosure: 5-conductor, 18 AWG, twisted, shielded, 100 feet maximum.
Retractor Assemblies: Packing gland assembly: 125 psig (8.6 barg ) max.
High pressure (crank) retractor: NPT 600 psig (41.4 barg), ANSI 150 flange & ANSI 300 flange, no valve supplied.
Installation: Fox Thermal-supplied compression fitting connects to customer-supplied ¾" female coupling welded to pipe. Compression fitting included with flow body.

FT3 Approvals

CE: Approved

  • EMC Directive; 2014/30/EU
  • Electrical Equipment for Measurement, Control, and Lab Use: EN61326-1:2013
  • Low Voltage Directive (LVD): 2014/35/EU
  • Product Safety Testing: EN61010-1:2010
  • Pressure Equipment Directive: 2014/68/EU
  • Weld Testing: EN ISO 15614-1 and EN ISO 9606-1, ASME B31.3

FM and FMc: Approved

  • Class I, Div. 1, Groups B, C, D;
  • Class II, Div. 1, Groups E, F, G;
  • Class III, Div. 1; T3C, Ta = -40°C to 70°C;
  • Class I, Zone 1, AEx/Ex d IIB+H2 (T6, T4, or T1*);Ta = -20°C to 70°C; Type 4X (IP67)

ATEX (FM12ATEX0034X): Approved

  • II 2 G Ex db IIB+H2 (T6, T4, or T1*) Gb Ta = -20°C to 70°C; IP67
  • II 2 D Ex tb IIIC (T85°C, T135°C, or T450°C*) Db Ta = -20°C to 70°C; IP67

IECEx (IECEx FMG 12.0010X): Approved

  • Ex db IIB+H2 (T6, T4, or T1*) Gb Ta = -20°C to 70°C; IP67
  • Ex tb IIIC (T85°C or T135°C*) Db Ta = -20°C to 70°C; IP67**

ATEX and IECEx Standards:

  • EN 60079-0: 2012 + A11:2013
  • EN 60079-1: 2014
  • EN 60079-31: 2014
  • EN 60529: 1991 +A1: 2000
  • IEC 60079-0: 2011
  • IEC 60079-1: 2014
  • IEC 60079-31: 2013
  • IEC 60529: 2001

Optional items available for the Model FT3 Flow Meter:

Talk with our application specialist or a rep near you for sizing and materials requirements

  • Insertion probe or inline models
  • FC20 Flow Conditioner for use with insertion style FT3
  • AC or DC power options
  • Remote models available with remote J-box
  • Cable for remote
  • Remote Mounting Kit for remote enclosures
  • Retractors
  • Extra Instruction Manual
  • Stainless Steel Tags
  • Certificate of Conformance
  • Certificate of Origin
  • USB Cable
  • Teflon Ferrule Kit
  • Flow meter cleaned and bagged for Oxygen service
  • Remote Mounting Kit for remote enclosures

FT3 Downloads

Additional Model FT3 Information to View and/or Download
Model FT3 Datasheet
FT3 Model Codes
FT3 Display Configuration Codes
FT3 Flowmeter Features
FT3 Procurement Specifications (.pdf)
FT3 Procurement Specifications (.docx)
FT3 Application Data Sheet (.pdf)
FT3 Application Data Sheet (.xlsx)
FT3 Instruction Manual
Troubleshooting Guide
FT3 CAL-V™ Example Certificate
FT3 Zero CAL-CHECK® Example Certificate
FT3 Data Logger Datasheet
FT3 Data Logger Manual

Note regarding VCP Driver: If the PC is connected to the Internet and running Windows® 7, 8, or 10, the PC will try to automatically load the VCP driver. If the driver does not load automatically, we have supplied a link above.

Other Downloads

FT3 Dimensional Drawings

FT3 Insertion Models
Local electronics, probe without retractor
Local electronics, probe with retractor
Remote electronics, probe without retractor
Remote electronics, probe with retractor
FT3 Inline Models
Local electronics, NPT end connections
Local electronics, 150# flange end connections
Remote electronics, NPT end connections
Remote electronics, 150# flange end connections
Fox 3D Viewer

FT3 Awards

Winner of Processing's Breakthrough Products Award

Winner of Flow Control's 2013 Innovation Award!

The votes are in! The Fox Model FT3 Thermal Mass Flowmeter and Temperature Transmitter has won the Flow Control 2013 Innovation Awards. The innovative Calibration Validation feature, using the CAL-V and Zero CAL-CHECK® tests, has paved the way for this advanced meter to garner the votes necessary to win this honor. Fox is very pleased and would like to thank all who have voted for this outstanding product.

Read the Digital Issue of Flow Control’s Announcement...

Winner of the 2014 Flow Control Innovation Award

Winner of Processing’s Breakthrough Products of the Year Award!

Processing Magazine has awarded Fox Thermal’s Model FT3 Thermal Mass Flowmeter & Temperature Transmitter the Breakthrough Products of the Year award for 2012. These awards recognize products, technologies and services that made significant contributions in the process industries within the last year and are expected to impact the industry for years to come.

Read the article describing Calibration Validation feature of the Model FT3.

Fox Thermal Model FT3 Flow Meter

The Fox Thermal Model FT3, a multiple award-winning thermal gas mass flow meter manufactured in the United States by Fox Thermal.

The Model FT3 was designed with our oil and gas customers in mind. This meter is Quad O (OOOO) compliant and is perfect for use in flare gas applications along with other fuel gas measurement.

The Model FT3 measures gas flow rate in standard units (SCFM, NM³/hr, LBS/HR, KG/HR & many more) without the need for temperature and pressure compensation.

FT3 View™ - a free software tool –- allows the user to connect to and configure the FT3 using USB to a PC or laptop.

Common Features for Fox Thermal Model FT3 Flow Meter:

  • Measures process gas flow rate/total and temperature
  • A USB connection is standard (free FT3 View™ Software); Optional HART and RS485 Modbus communication protocols
  • Optional on-board display and configuration panel
  • Equipped with the PowerPro™ thermal mass flow sensor
  • One discrete output is programmable for either pulse (for totalizing flows) or alarms
  • One discrete input to reset total or select a different calibration on 2 gas curves
  • 4-20mA output proportional to mass flow rate
  • Click the Approvals tab for Model FT3 Agency Approvals.
  • Calibration Validation with the CAL-V™ and Zero CAL-CHECK® features.
  • NIST-traceable calibration
  • Wide measurement range
  • 1% R + 0.2% FS flow accuracy
  • 24 VDC or optional 100 to 240VAC in local or remote enclosures

For complete specs please see the Fox Thermal Model FT3 Flow Meter Datasheet.

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