LIQUI-FLOW™ 'Industrial Style' L23I+C2I

Digital Thermal Liquid Mass Flow Controller, Industrial Style

  • Fast and accurate measuring signal
  • Insensitive to mounting position
  • Suitable for liquids with low boiling points
  • Analog, RS232 or fieldbus communication
  • Rugged, IP65 enclosure

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LIQUI-FLOW™ 'Industrial Style'L23I+C2I

Liquid Mass Flow Controllers for low flow rates, industrial style

Bronkhorst® model L23I+C2I Liquid Flow Controllers (LFCs) are suited for precise measurement and control of flow ranges between 2…100 g/h and 20...1000 g/h at operating pressures up to 100 bar. The LFC consists of a thermal mass flow sensor and a microprocessor based pc-board with signal and fieldbus conversion and a PID controller for mass flow control by means of an integrated control valve. The "Industrial Style" LIQUI-FLOW™ model is of rugged design (IP65) for use in industrial environments or even Zone 2 hazardous areas, with optional ATEX Cat. 3 approval.

LIQUI-FLOW™ series are equipped with a digital pc-board, offering high accuracy, excellent temperature stability and fast response. The main digital pc-board contains all of the general functions needed for measurement and control. In addition to the standard RS232 output the instruments also offer analog I/O. As an option, an on-board interface can be mounted to provide DeviceNet™, PROFIBUS DP, Modbus or FLOW-BUS protocols.

Technical specifications

Measurement / control system
Flow range (intermediate ranges available)min. 2…100 g/h
max. 20…1000 g/h
(based on H2O)
Accuracy (incl. linearity) (based on actual calibration)± 1 % FS
Repeatability< 0,2 % FS (typical H2O)
Turndown ratio1:50 (2…100%)
Settling time (in control, typical)< 2 sec.
Operating temperature5 … 50 °C
Temperature sensitivity± 0,1% FS/°C
Max. Kv-value2,37x10-3
Max. fluid viscosity0.1 Pa*s
Attitude sensitivitynegligible
Warm-up time30 min. for optimum accuracy;
2 min for accuracy ± 2% FS
Mechanical parts
Material (wetted parts)stainless steel 316L/320;
other on request
Pressure rating (PN)100 bar abs
Max. ΔP10 bar dif
Process connectionscompression type or face seal (VCR/VCO) couplings
Purge connection1/8” OD compression type or 1/8" VCR
SealsKalrez® (FFKM); other on request
Ingress protectionIP65
Electrical properties
Power supply+15 … 24 Vdc +/-10%
Max. power consumption
15 V
24 V
at voltage I/O
285 mA
250 mA
at current I/O
305 mA
270 mA
extra for fieldbus
<75 mA
<50 mA
Analog output0…5 (10) Vdc or 0 (4)…20 mA (sourcing output)
Digital communicationstandard: RS232;
options: PROFIBUS DP, DeviceNet™, Modbus RTU, FLOW-BUS
Electrical connection
Analog/RS2328 DIN (male)
PROFIBUS DPbus: 5-pin M12 (female);
power: 8 DIN (male)
CANopen® / DeviceNet™5-pin M12 (male)
FLOW-BUS/Modbus-RTU/ASCII5-pin M12 (male)
Control valve options
External actuator options to be connected to the controller
Ex-proof specifications
Approvals / certificates

Technical specifications subject to change without notice.

For dimensional drawings and hook-up diagrams please visit the product page on our website


LIQUI-FLOW brochure

General manual digital instruments
Operating instructions digital instruments


Hook-up diagrams
Analog IO - RS232

Bronkhorst USA LLC

57 South Commerce Way
Suite 120
USA - Bethlehem, PA 18017 
Tel.  +1-610-866-6750

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