Ultrasonics Principle Video

Understanding the principles of ultrasonic flow

FS220 Overview (Updated FST020)

The SITRANS FS220 digital clamp-on ultrasonic flowmeter provides the most essential flow measurement functionalities with superior accuracy, cost efficiency and ease of use. It is the best-in-class solution for straightforward flow monitoring of liquid processes in number of industries, including water and wastewater, HVAC, power and chemical.

The SITRANS FS220 flow system consists of a SITRANS FST020 transmitter paired with SITRANS FSS200 clamp-on ultrasonic sensors, which are available in three different models: WideBeam® (High-Precision), Universal and High-Temperature.

The FST020 transmitter has been upgraded to deliver leading reliability, user-friendliness and options for customization, while the FSS200 sensors feature low maintenance and high precision – even for applications with high levels of aeration or suspended solids.

Application examples include water and wastewater, HVAC and power, chemical.


FST020 wall-mount or pipe mount transmitter

The tried-and-trusted SITRANS FST020 transmitter has been upgraded to deliver enhanced  performance, userfriendliness and options for customization. Driven by the powerful  performance PLUSTM algorithm, it measures virtually any liquid with consistently high accuracy of 1% of flow
rate, improved zero stability resulting in minimal need to set a zero point

FSS200 sensors

Ultrasonic sensors transmit and receive acoustic signals directly through existing pipe walls. To cover the widest possible range of applications, Siemens offers 3 different type of clamp-on ultrasonic sensors: WideBeam® (High precision), Universal and High Temperature. WideBeam® produces a strong, focused signal that optimizes the signal-to-noise ratio, reduces sensitivity to changes in temperature, density or viscosity.

FSS200 clamp-on ultrasonic sensors are easy to install and require virtually no maintenance since they never come in contact with the process fluid.


Specifications SITRANS FST020 wall-mount transmitter


Single channel


Modbus RTU, compatible with SIMATIC PDM

Enclosure rating

IP65 (NEMA 4X)


240 x 160, fully graphical

Power supply

100-240 V AC 15 VA max., 11.5-28.5 V DC 7.5W max.


2x digital inputs for totalizer start/stop and reset


1 x 4-20 mA, 1 x relay, 1 x pulse/frequency


1% for velocities ≥ 1 ft/s (0.3 m/s)

Flow range

±40 ft/s (±12 m/s), bidirectional

Pipe size range

0.5" to 394" (12.7 mm to 10 m)



Specifications SITRANS FSS200 clamp-on ultrasonic sensors


Conductive and non-conductive liquids

Pipe sizes

0.5" to 394"

Sensor materials

Size A/B: Polyetherimide, aluminum, optional stainless steel
Size C/D: Polyetherimide, stainless steel

Size A/B: Polyetherimide, aluminum, optional stainless steel
Size C/D/E: Polyetherimide, stainless steel (Size C/D/E);

High-Temperature: Stainless steel

Temperature range

WideBeam®: -40 to 250 °F
Universal: -40 to 250 °F
High-Temperature: -40 to 450 °F

Pipe material

WideBeam®: Steel and carbon steel
Universal: Most non-steel
High-Temperature: Steel and non-steel


FM, FMc, ATEX, IECEX (Zone 0,1 and 2)


Built on the same architecture as other next-generation digital flow systems from Siemens, the SITRANS FS220 features among others:

  • High accuracy and repeatability – accuracy of 1% of flow rate and repeatability of 0.25% according to ISO 11631

  • Exceptional zero stability – minimal need to set a zero point

  • Best-in-class user-friendliness – fully graphical display with simple menu navigation, multiple setup wizards and the option to display up to 6 customizable parameters on the same screen

  • Simplified installation – multiple setup wizards guide you through every step of commissioning

  • Easy servicing – includes removable SensorFlash® microSD card and built-in USB service port

FS200 Clamp-on Utility Software for SITRANS FS230/FS220 flowmeters

This software utility is an update to the previously released Si-Ware software. The utility allows you to interface with any Siemens FS220 or FS230 Clamp-on flow meter to assess the condition of your flowmeter installation and to collect data for comparison with prior baseline data.