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Measures Masses With Exemplary Accuracy! Flow Measurement of Liquids in Laboratory Analysis and Industry

Which flow sensor is 5 cm long, weighs only 7 g and can measure liquids up to 1,000 ml/min with exemplary accuracy?

Answer A:       SLF3S-0600F

Answer B:       SLF3S-1300F

Answer C:       SLF3C-1300F

Answer D:       SLF3S-4000B

The correct answer can be found below in the product table for the SLF3x family from SENSIRION.

The challenge of high flow rates

Measuring high flow rates with Coriolis or ultrasonic flow meters is very accurate, but often not ideal for two reasons: the devices are expensive and take up a lot of space.

In contrast, cheaper turbine meters are often inaccurate and do not provide a calibrated signal. There are also problems with reliability because the measuring wheel can block.

SENSIRION closes this gap with a new flow sensor family based on proven CMOSens® technology. The SLF3x series is ideal for laboratory analysis and industry and also records higher flow rates with the usual high quality, precision and at a good price/performance ratio. These sensors weigh just 7 g and are only 5 cm long.

Thermal measuring principle
The liquid sensors in the SLF3x series are based on the manufacturer's proven CMOSSens® technology:

A microscopically small heating element adds a tiny ‘heat cloud’ to the liquid, which is deformed by the flow. Two highly sensitive microsensors measure the temperature upstream and downstream of the heating element and record the deformation of the heat cloud, which is represented as the temperature difference between the two sensors. This value is converted by the microchip into a fully calibrated and linearised flow rate and output.

In order not to disturb the flow and to protect the sensor chip from media influences, SENSIRION installs the microsensor chip outside the channel. The flow measurement therefore takes place ‘through the channel wall’, i.e. both the heat from the heating element and the signals from the two temperature sensors penetrate the membrane. The thermal properties of the membrane therefore have a major influence on the performance of the sensor.

Steel diaphragm for larger measuring and wider flow range
If high flow rates are to be measured, the heat must be effectively introduced into the flow channel. For this reason, the developers at SENSIRION have equipped the SLF3x product family with a steel diaphragm. With the SLF3S-1300F, this not only enables a larger measuring range - up to 65ml/min - but also a wider flow range. The most recent derivative, the SLF3S-4000B, is moving into completely new dimensions by further optimising the hydrodynamic properties: This high-flow sensor is even capable of measuring flow rates of up to 1,000ml/min.

High media compatibility

The medium to be measured only comes into contact with three materials in the sensor. All wetted materials (steel diaphragm, polyphenyl sulphide, epoxy) are extremely inert, which ensures very good chemical and biological compatibility.

The flow rate can be measured bidirectionally. The sensor is suitable for very dynamic flows as well as for liquids with high viscosity.

Equipped in this way, the SLF3x family is ideal for use in medicine and life sciences, diagnostics, the semiconductor industry, factory automation and energy management applications.

The ‘special one’, flow rate combined with thermal conductivity

The SLF3C-1300F has a unique selling point within the sensor family. It measures more than just the flow rate. You can also measure the thermal conductivity of the liquid and analyse it further. This opens up further possibilities for your system, such as

• Concentration monitoring:
  Measuring the concentration of two-component mixtures such as oil or glycol in water.
• Accuracy testing:
  Ensuring that the fluid is identical to the calibrated fluid to ensure accurate flow measurement.

The SLF3x family at a glance:

Article	SLF3S-0600F	SLF3S-1300F	SLF3C-1300F	SLF3S-4000B
Case
Full scale flow	2000 µl/min H2O 2000 µl/min IPA	40 ml/min H2O 40 ml/min IPA	40 ml/min H2O 40 ml/min IPA	600 ml/min H2O 600 ml/min IPA
Sensor output limit	3250 µl/min H2O 3250 µl/min IPA	65 ml/min H2O 65 ml/min IPA	65 ml/min H2O 65 ml/min IPA	1000 ml/min H2O 1000 ml/min IPA
Pressure	12 bar	12 bar	12 bar	3 bar
Voltage	3,5 V	3,5 V	3,5 V	3,5 V
Interface	I²C	I²C	I²C	I²C
Special feature			Media identification
Data sheet	SLF3S-0600F	SLF3S-1300F	SLF3C-1300F	SLF3S-4000B

The SLF3S-0600F and SLF3S-1300F will also be available as SLF3S-0600D and SLF3S-1300D for downmount/manifold mounting from Q4/2024.

Easy start with evaluation kit and GLYN-SUPPORT

A special evaluation kit is available for each flow sensor. It makes it easy to get started with flow measurement.
The kit consists of the sensor itself, a mounting bracket, ribbon cable and a USB sensor cable for analysing the sensor directly on the PC.
The sensors with 1/4-28 UNF ports are even supplied with fluidic connections.

The associated ControlCenter software can be downloaded free of charge from the manufacturer.

Complete overview - SENSIRION flow sensors for liquids

If you are looking for other flow sensors with a measuring range from single-digit nanolitres to one litre per minute, you will find an initial important decision-making aid in the attached overview.

We will be happy to answer any further questions you may have personally.