Digital Thermal Liquid Mass Flow Meter

  • Fast and accurate measuring signal
  • Insensitive to mounting position
  • Very small internal volume
  • Suitable for liquids with low boiling points
  • Analog, RS232 or fieldbus communication
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Liquid Mass Flow Meters for low flow rates

Bronkhorst® model L13 Liquid Flow Meters (LFMs) are suited for precise measurement of flow ranges between 0,25…5 g/h and 5...100 g/h at operating pressures up to 100 bar. The LFM consists of a thermal mass flow sensor and a microprocessor based pc-board with signal and fieldbus conversion and a PID controller for optional mass flow control by means of a separately mounted control valve.

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, EtherCAT® or FLOW-BUS protocols.

Technical specifications

Measurement system
Flow range, based on H2O
(intermediate ranges available)
min. 0,25…5 g/h
max. 5...100 g/h
Accuracy (incl. linearity)
(based on actual calibration)
±1% FS
Turndown FS <50 g/h : 1:20 (5...100%);
FS >50 g/h : 1:50 (2...100%)
Repeatability < 0,2% FS (typical H2O)
Operating temperature 5…50°C
Temperature sensitivity ±0,1% FS/°C
Attitude sensitivity negligible
Warm-up time 30 min. for optimum accuracy;
2 min for accuracy ± 2% FS
Mechanical parts
Material (wetted parts) stainless steel 316L/320;
others on request
Pressure rating 100 bar abs
Process connections compression type or face seal couplings
Seals Kalrez®-6375;
others on request
Ingress protection (housing) IP40
Electrical properties
Power supply +15…24 Vdc +/-10%
Max. power consumption
(meter only)
15 V
24 V
at voltage I/O
100 mA
65 mA
at current I/O
120 mA
85 mA
PROFIBUS DP add 53 mA (15 V supply) or 30 mA (24 V supply)
EtherCAT® add 66 mA (15 V supply) or 41 mA (24 V supply)
DeviceNet™ add 48 mA (24 V supply)
Analog output 0...5 (10) Vdc or 0 (4)...20 mA (sourcing output)
Digital communication standard: RS232;
options: PROFIBUS DP, DeviceNet™, EtherCAT®, Modbus RTU, FLOW-BUS
Electrical connection
Analog/RS232 9-pin D-connector (male)
PROFIBUS DP bus: 9-pin D-connector (female);
power: 9-pin D-connector (male)
DeviceNet™ 5-pin M12-connector (male)
EtherCAT® 2 x RJ45 modular jack (in/out)
FLOW-BUS/Modbus-RTU/ASCII RJ45 modular jack

Technical specifications and dimensions subject to change without notice.

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


LIQUI-FLOW series L10-L20 brochure

General manual digital instruments
Operating instructions digital instruments

Hook-up diagrams
Analog IO - RS232

Dimensional drawing
Dimensional drawing LIQUI-FLOW L13

Bronkhorst High-Tech B.V.

Nijverheidsstraat 1A
NL-7261 AK Ruurlo (NL)
Tel. +31 573 45 88 00
[email protected]

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