Direct Thermal Mass Flow Controller for Gases, IP65 protected

  • Proven direct inline CTA sensor (no bypass)
  • Compact, rugged design (IP65, dust and waterproof)
  • Less sensitivity to humidity or dirt
  • Optional with integrated TFT display
  • Very good price-performance ratio


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Compact IP65 Mass Flow Controllers for low flow rates of gases

Bronkhorst® model D-6321 Mass Flow Controllers (MFCs) are suited for precise measurement of flow ranges between 0,05…1 ln/min and 0,35…7 ln/min at operating pressures between vacuum and 10 bar (Aluminium) or 20 bar (Stainless Steel). The MFC consists of a proven inline thermal (CTA) mass flow sensor, a precise control valve and a microprocessor based pc-board with signal and fieldbus conversion. As a function of a setpoint value, the flow controller swiftly adjusts the desired flow rate. The instument is IP65 complient and can optionally be equipped with a modern, multi-functional and multi-colour display, with operator buttons on the instrument.

The digital MASS-STREAM™ series is characterized by a high degree of signal integrity and, as an option, up to 8 calibration curves of different gases and process conditions can be memorized in the instrument. 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-RTU or FLOW-BUS protocols.

Technical specifications

Measurement / control system
Flow range, based on N2
(intermediate ranges available)
min. 0,05…1 ln/min
max. 0,35…7 ln/min
Accuracy (based on calibration with Air at 5 bar (a) and T = 20 °C) ±2% FS including non-linearity*
±1,5% FS on request*
Repeatability < 0,2% FS
Turndown 1:20
Type of gases almost all gases, compatible with chosen materials
Response time sensor approx. 0,3 sec.
Settling time (controller) plus approx. 2 seconds
Operating temperature 0…50°C
Temperature sensitivity ±0.2% Rd/°C (Air)
Pressure sensitivity ±0,3% Rd/bar typical (Air)
Control stability < 0,2% FS typical
Max. Kv-value 6,6 x 10-2
Leak integrity tested < 2 x 10-8 mbar l/s He
Attitude sensitivity at 90° deviation from horizontal max. error 0,2 % at 1 bar typical N2
Warm-up time 30 min. for optimum accuracy,
within 30 seconds for accuracy ±4% FS
Mechanical parts
Sensor Stainless steel SS 316 (AISI 316L)
Instrument body Aluminium AL 50ST/51ST (anodised) or stainless steel SS 316
Seals standard: Viton®; options: EPDM, Kalrez® (FFKM), FDA and USP Class VI approved compounds
Sieves and rings Teflon or stainless steel SS 316
Pressure rating 10 bar g for instrument body in aluminium,  
20 bar g for instrument body in stainless steel SS 316
Process connections compression type or face seal couplings

Ingress protection
(housing, optional display)

Electrical properties
Power supply +15…24 Vdc ±10%
Current peak values Meter approx. 75 mA at 0% flow
approx. 125 mA at 100% flow
Current peak values Controller add 250 mA
add 30 mA for display, if applicable
add 50 mA for additional interface, if applicable
Analog output/command 0...5 (10) Vdc or 0 (4)…20 mA
(sourcing output)
Digital communication standard: RS232
options: PROFIBUS DP, DeviceNet™, Modbus-RTU, FLOW-BUS
Electrical connection
Analog/RS232 8 DIN (male);
PROFIBUS DP bus: 5-pin M12 (female);
power: 8 DIN (male)
Devicenet™ 5-pin M12 (male)
Modbus-RTU/FLOW-BUS 5-pin M12 (male)

* The calibration of instruments in the lower measurement range and for some gases
   could result in a reduced accuracy.

Technical specifications and dimensions subject to change without notice.

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


MASS-STREAM D-6300 Brochure

Manual MASS-STREAM D-6300 display
Operating instructions digital instruments

Hook-up diagrams
Analog I-O RS232
PROFIBUS DP 9-pin Sub-D connector
PROFIBUS DP with 5-pin M12 connector

Solids 3D
D-6310, D-6311, D-6320 and D-6321

Bronkhorst High-Tech B.V.

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

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