
MODEL FT2A FLOW METER TROUBLESHOOTING GUIDE
Rev. B
Precision Mass Flow Measurement
An ON
I
CON Brand
Phone: (831) 384-4300 • Fax: (831) 337-5786 • www.foxthermal.com
5. What is the measured input power to the ow meter? Refer to FT2A Instruction Manual for input power
requirements.
6. Test/Check fuses and LED status lights for FT2A.
• With the power o, take a resistance measurement across the fuse to ensure it measures less than 1 ohm.
• Is the LP4 LED on the main board emitting a steady orange light?
• Is the green LP1 LED on the inside of the display board blinking once per second?
4. Have any of the ow meter settings been changed since you received the meter from Fox Thermal?
5. If advised by a Fox technical representative please conrm the following sensor resistances are correct. Turn
o power to meter and disconnect sensor wires from TS 8 (the sensor termination terminal strip located at the
bottom of FT2A main board) before taking measurements.
• Sensor wiring: White to White wires= 200 to 225 ohms, Red to Red = .1 ohms, Red to Yellow = 9 to 10
ohms.
Section C: Investigating ow meter inaccuracy:
1. How high or low is the ow meter reading and at what ow rate? Please provide specic data.
2. Conrm that the 4mA and 20mA scaling in the PLC or DCS matches the scaling in the ow meter's settings. If
you are using the 4-20mA output also conrm that the measurement unit (SCFM, KG/HR, NM3H, etc.) in the
Fox meter is the same as in your PLC/DCS.
3. Did the meter ever read accurately or do you believe it has measured incorrectly since it was installed?
4. Is the gas you are measuring the same as is shown on the ow meter calibration certicate? If not, what gas
are you currently measuring?
5. Has there been any change in meter location or pipe conguration?
6. Is the insertion depth setting in accordance with Fox Thermal installation instructions? Refer to FT2A Instruction
Manual for insertion depth.
7. What is the inside diameter (ID) of the pipe? Is the actual pipe ID the same as listed on the ow meter's
Calibration Certicate? Is the area setting programmed into the ow meter correct?
8. Compare the STP (Standard Temperature and Pressure) settings (values and units) in the meter with the
information recorded on the calibration certicate. Do the settings match? This is a requirement for accurate
measurement.
9. How much straight pipe is upstream and downstream of the ow meter? Fox recommends a minimum of 15
diameters of straight pipe upstream of the ow meter and 10 diameters downstream. Refer to FT2A Instruction
Manual for upstream and downstream conditions for insertion and owbody types.
10. Is the arrow on the ow meter probe pointing in the direction of ow? If your meter is an inline-type, is the
ow body or spool piece installed with the ow conditioner on the upstream side of the sensor? Refer to the
FT2A Instruction Manual for information regarding the direction of ow.
11. What is the CSV voltage? Please refer to the ow meter Instruction Manual.
For assistance contact the Fox Thermal Service Department:
Phone: 831-384-4300