Karman vortex flowmeter vloeistof

Karman vortex flowmeter for liquids: KOFLOC FML-300

The KOFLOC FML-300 is a Karman vortex flowmeter for liquids with integrated temperature correction. Where standard vortex meters become inaccurate with temperature changes, the FML-300 compensates for this automatically via a built-in temperature sensor. The result is a stable, repeatable measurement over the entire temperature range of 15 to 60 degrees Celsius.

The wetted parts are made of New PFA, compatible with virtually all aggressive chemicals including HF, HCl, H2SO4 and etching liquids. This makes the FML-300 ideally suited for semiconductor production, chemical process installations and high-purity laboratory environments.

Not sure which model suits your application? Ask for technical advice right away.

Why choose the KOFLOC FML-300?

In 2024 the FML-300 series won the Kyoto Prefecture Small and Medium Enterprise Technology Innovation Award and the 35th Small/Mid Enterprise Promotion Award in the New Product category. Two independent recognitions for a measuring principle that solves a concrete problem that has existed with standard vortex meters for years.

Feature 1: temperature correction for accurate measurement at varying liquid temperatures

Standard Karman vortex flowmeters measure the frequency of vortices behind a bluff body. That frequency is proportional to the flow velocity, but the viscosity of liquids changes with temperature. The result: accuracy errors that can amount to several percent with temperature changes.

The FML-300 solves this with a third sensor in the measuring chamber: a temperature sensor directly in the flow path. Using a built-in correction table, the meter continuously adjusts the result based on the current liquid temperature. The measurement remains accurate from 15 to 60 degrees Celsius, even in systems with variable process temperatures.

Accuracy FML-301 to FML-305: plus or minus 2,0% F.S. at 25 degrees CelsiusAccuracy FML-306: plus or minus 3,0% F.S. at 25 degrees CelsiusRepeatability all models: plus or minus 0,5% F.S. Temperature accuracy: plus or minus 2 degrees Celsius, plus or minus 0,15 x delta T degrees Celsius

Feature 2: New PFA wetted parts, without O-ring

The wetted parts of the FML-300 are made entirely of New PFA from Daikin (AP-201SH/AP-230SH) and Mitsui Chemours (451HP-J). These are the same fluororesin grades used in semiconductor production lines worldwide.

New PFA combines excellent chemical resistance, heat resistance and weather resistance. Thanks to the O-ring-free design, there are no elastomers that can degrade when exposed to aggressive media.

Compatible liquids (fully compatible):

The compatibility list is indicative. Depending on concentration and temperature, Inacom always advises based on your specific application.

Feature 3: compact design for multiple mounting

The FML-300 is 35% narrower than its predecessor. It is specifically designed for installations where several flowmeters are mounted side by side on a single device or in a rack. The compact size eliminates interference between adjacent units and significantly reduces the total installation space.

Feature 4: wide flow range in six models

The FML-300 series consists of six standard models that together cover a flow range of 0,3 to 250 litres per minute. Each model is optimised for its range and has an oblong flow channel cross-section that enables stable and accurate measurement at low flows.

Accuracy guaranteed at liquid temperatures of 15 to 60 degrees Celsius. Liquid temperature range: 0 to 90 degrees Celsius (no freezing or boiling).

Feature 5: IP65 housing, dust- and splash-proof

The FML-300 has a degree of protection equivalent to IP65 according to IEC standards. This means complete dust sealing and protection against direct water jets from any direction. This makes the meter suitable for use in humid process environments, during cleaning processes and in outdoor installations.

Technical specifications

Signal outputs FML-300 series

Measuring principle: how does a Karman vortex flowmeter work?

When a liquid flows past an obstacle, regular, alternating vortices form behind that obstacle: the so-called Karman vortex street. The frequency at which these vortices form is directly proportional to the flow velocity of the liquid.

The FML-300 detects this vortex frequency with a piezoelectric element in an oblong flow channel cross-section. This design offers three advantages over round or oval channels:

• Stable and accurate measurement at low flow rates
• More cost-efficient piezoelectric detection principle
• Shorter piezo element length reduces sensitivity to external vibration

The meter has no moving parts. This makes the FML-300 virtually maintenance-free and particularly suitable for continuous use in processes where downtime is undesirable.

Installation requirements: straight pipe length

The accuracy of the FML-300 depends on uniform flow at the sensor. To minimise the influence of turbulence and pulsations, the following guidelines apply:

Instroom zijde (IN): aanbevolen rechte leidinglengte 10D (binnendiameter x 10) Uitstroom zijde (OUT): aanbevolen rechte leidinglengte 5D (binnendiameter x 5)

Practical measurements with the FML-303 show that with an inlet length of 10D (approx. 1000 mm) the deviation remains limited to approx. 1% F.S. With shorter pipe lengths, measurement uncertainty increases. Inacom advises you on the optimal installation for your specific situation.

Fields of application

Semiconductor and high-purity production

The FML-300 is specifically developed and tested for use in semiconductor production environments. Applications include:

• Wet cleaning equipment (wafer cleaning)
• CMP (chemical mechanical planarisation) production equipment
• Semiconductor coating lines
• LED production equipment

[Insert image here: slide 20 from the PDF, schematic overview of the wet cleaning process with FML-300 inline]

Particle evaluation data (FML-304) shows that the number of particles in the liquid flow quickly drops to background level after connecting the meter. Metal/organic leaching evaluation (performed by Kinki Analysis Center, ref P21-6752-3Z1) confirms ultra-low leaching of metals and organic substances.

Chemical process installations

• Flow monitoring of chemicals during dosing and mixing
• Monitoring of process liquids at variable temperature
• Pump output measurement with corrosive media

Laboratory and analytical

• Koelwatercontrole in analyseapparatuur
• Flowmonitoring in farmaceutische productie
• Measurement of ultrapure water in analytical systems
• Plating and lens cleaning equipment

Display functionality and version options

The FML-300 is available with and without display. The display version offers:

• Display of instantaneous flow rate, accumulated flow and liquid temperature
• Two adjustable alarm limits (AL1 and AL2) with red LED indication for upper and lower limit monitoring of both flow and temperature
• Digital communication via RS-485 (MODBUS RTU) for integration into SCADA or PLC environments
• Adjustable time constant (levels 1, 2 and 4) for adjusting the response behaviour
• Accumulated flow value up to a maximum of 99.999.999, resettable via the settings menu

Without display, all signals are available via analogue and pulse outputs for direct connection to existing process control.

Frequently asked questions about the KOFLOC FML-300

Is the FML-300 suitable for corrosive chemicals?

Ja. The wetted parts are made entirely of New PFA, a fluororesin material compatible with virtually all chemicals used in semiconductor and chemical processes, including HF, HCl, H2SO4, TMAH and etching liquids. There are no elastomers or O-rings in the wetted part.

What is the difference between the FML-300 and a standard Karman vortex flowmeter?

The core difference is the integrated temperature correction. Standard vortex meters measure the vortex frequency, but do not compensate for the influence of temperature on liquid viscosity. The FML-300 continuously measures the liquid temperature and automatically adjusts the flow measurement via a factory calibration table. This delivers considerably higher accuracy in processes with variable temperature.

Which model should I choose for my flow range?

Together, the six models cover 0,3 to 250 litres per minute. FML-301 and FML-302 are for low flows (0,3 to 4 L/min), FML-303 and FML-304 for the mid range (2 to 50 L/min), FML-305 and FML-306 for higher flows (10 to 250 L/min). Inacom is happy to advise you based on your specific flow profile and process liquid.

How much straight pipe is needed before and after the meter?

De aanbevolen rechte instroomlengte is 10D (binnendiameter x 10), uitstroomlengte is 5D. With an inlet length of approx. 10D, the measurement deviation remains limited to approx. 1% F.S. Inacom can advise you on the optimal installation and possible correction options for non-standard pipe configurations.

Can the FML-300 be integrated into my PLC or SCADA system?

Ja. The display version has RS-485 with MODBUS RTU protocol. All models also provide an analogue output of 4 to 20 mA and a pulse output for direct connection to existing process control.

Is the FML-300 available as an OEM component?

Ja. KOFLOC and Inacom supply OEM versions for integration into equipment. Contact our technical department for OEM specifications and prices.

What are the cleaning and maintenance requirements?

The FML-300 has no moving parts and requires no periodic mechanical maintenance. If the measuring channel becomes contaminated, flushing with a compatible liquid is sufficient. For semiconductor applications, the channel is easy to flush according to standard cleanroom procedures.