『Ifm Clamp on Flow Meter: Programming Thermal Dispersion Temperature and Rate Constants on Process Pipes』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
Ifm Clamp On Flow Meter: Programming Thermal Dispersion Temperature And Rate Constants On Process Pipes
Quick Answer: Programming an ifm clamp on flow meter on a process pipe needs five values: pipe outer diameter, wall thickness, medium, temperature, and rate constant. Set the temperature constant before the rate constant. A wrong medium temperature can shift compressed air flow by 2 to 5 percent.
Silver Automation Instruments works with process engineers in Southeast Asia, Oceania, Latin America, Africa, and the Middle East. Our support team often gets questions about ifm clamp on flow meter programming for gas and liquid lines in oil and gas, water and wastewater, chemical, food and beverage, and marine plants. This article gives a practical setup sequence for thermal dispersion temperature and rate constants on process pipes.
What The Temperature Constant And Rate Constant Do
Thermal dispersion flow meters use two PT100 sensors. One sensor is heated. The other measures process temperature. Flow removes heat from the heated sensor. The transmitter converts the temperature difference to mass flow. The raw signal depends on fluid type, pipe material, and process temperature. The temperature constant corrects for the medium temperature. The rate constant is the final multiplier that aligns the meter with a reference flow in kg/h or Nm³/h.
Data To Collect Before You Start Programming
Collect six values before entering the setup menu. Pipe outer diameter. Example: 48.3 mm for a DN40 steel pipe. Wall thickness. Example: 3.0 mm for schedule 40. Pipe material. Stainless steel 304 and carbon steel do not transfer heat the same way. Process medium. Compressed air, nitrogen, and carbon dioxide all have different thermal conductivity. Operating temperature in °C. Operating pressure in bar. Do not take wall thickness from a drawing alone. A customer in Argentina used schedule 40 wall thickness on a schedule 80 DN50 steam condensate line. The meter read 11 percent high until the wall thickness was corrected.
Temperature Constant Setup
The temperature constant is not the process temperature. It is a compensation factor inside the transmitter. Some firmware calls it Temp K or T-Const. Set the process temperature first. Use the temperature at the sensor location, not the compressor discharge. A 10 °C difference can shift the flow calculation by 2 to 3 percent on compressed air and nitrogen. Then set the temperature constant. Start at 1.000. If the meter reads high at a stable flow, reduce the constant. If it reads low, increase it. Change this before you touch the rate constant.
Rate Constant Setup
The rate constant is the last scaling factor. Start at 1.000. Run the process at a steady load for at least 30 minutes. Compare the meter against a reference. For compressed air, use a portable insertion flow meter. For fuel gas, use a Coriolis mass flow meter. If the reference says 210 kg/h and the ifm clamp on flow meter reads 203 kg/h, the new rate constant is 210 divided by 203, or 1.034. Do not change it more than 10 percent in one step. Big jumps usually mean a wrong pipe parameter, wrong fluid setting, or a moisture problem.
Common Pipe Settings And Field Examples
Co
Ifm Clamp On Flow Meter Or Silver Instruments
The ifm clamp on flow meter is useful for quick checks and for pipes that cannot be cut. But a clamp-on thermal device is not always the best permanent meter. Pipe scale, insulation, paint, and external heat affect the heat transfer path. If you need ATEX Zone 1 certification, HART data, or long term accuracy, an inline thermal mass flow meter from Silver Instruments is often a better fit. Silver Instruments supplies thermal mass flow meters for gas lines from DN15 to DN300. Outputs include 4-20 mA HART, RS485 Modbus, and pulse. Pressure ratings go up to 40 bar. For liquid lines, Silver Instruments supplies clamp-on ultrasonic flow meters and electromagnetic flow meters.
Programming Mistakes That Shift The Reading
One common mistake is entering internal diameter as outer diameter. On DN15 and DN20 lines this makes the reading low by 3 to 10 percent. Another mistake is using the rate constant to fix a wrong temperature setting. This only works at one operating point. When the process temperature changes, the meter drifts again. Forgetting to reset the totalizer after changing the rate constant is also common. The daily total will include the old and new constants.
FAQ: Five Key Questions
Can I use a clamp-on thermal dispersion flow meter on a plastic pipe?
No. Plastic and fiberglass pipes have low thermal conductivity. The heat transfer signal is weak and unstable. Use a clamp-on ultrasonic flow meter for plastic or fiberglass pipes.
What is the difference between the temperature constant and the rate constant?
The temperature constant corrects for the medium temperature. The rate constant is the final scaling multiplier. Change the temperature constant first. Change the rate constant last.
How often should I check the programming?
Every six months or after any pipe modification. Scale build-up, new paint, insulation, and process changes can all affect the measurement.
Can this method measure liquid flow?
Thermal dispersion is used mostly for gas flow. For liquid lines, use clamp-on ultrasonic, electromagnetic, or Coriolis flow meters. Silver Instruments can recommend the right type for your fluid.
What process data should I send to Silver Instruments for a quote?
Send pipe size in DN, fluid type, pressure in bar, temperature in °C, and flow range in kg/h or m³/h. Include the required output signal such as 4-20 mA HART or RS485 Modbus. You can reach Silver Instruments at Tel: +86-25-68650347, WhatsApp: +86-25-52155837, or WeChat: +86 15365082610.
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