Kofloc DF-350C Digital Mass Flow Meter

The Model DF-350 Series is a digital mass flow controller with an integral indicator that operates on a 24-V power supply. It offers features equivalent to the DF-250 Series designed for up to 50 SLM.


  • High accuracy (±1% S.P.), fast response (≤ 1 sec in all ranges)
  • Support of multiple ranges and multiple gases
  • Communication functions installed as a standard feature (RS485)
  • RoHS CE standard compliant
  • Driven by a single 24 V DC supply voltage
  • With or without indicator (selectable)
  • Selectable Input/output signal


Sensor type Thermal sensor
Valve type Normally closed proportional solenoid valve
Applicable gases*1 N2, Air, H2, He, Ar, O2, CO2, etc.
(Gases not specifically mentioned here are subject to calibration for N2 equivalent.)
Flow range*2 10 SCCM to 10 SLM 20 to 50 SLM
(20 to 30 SLM for CO2)
Control range 2 to 100% (F.S.)
Response*3 Total flow rate control range ≤ 1 sec (within ±2% F.S.)
Accuracy*4 ±1.0% F.S.
Repeatability ±0.25%F.S.
Operating differential pressure*5 50 to 300 kPa (100 to 300 kPa for Ar and CO2) 100 to 300 kPa (150 to 300 kPa for Ar and CO2)
Inlet maximum pressure 500kPa(G)
Proof pressure 980kPa(G)
External leak rate ≤ 1.0 x 10-8 Pa·m3/sec (He)
Temperature Working temp. 5 to 50℃
Accuracy guaranteed temp. 15 to 35℃
Allowable storage temp. -10 to 60℃
Allowable operating humidity 10 to 90% RH (without dew condensation)
Materials of the gas contact part SUS316, SUS316L, magnetic stainless steel, Ni, PTFE, PCTFE, and FKM
Electrical connection D-sub 15-pin male, high density, HR-10A (two)
Flow rate setting signal 0 to 5 V DC (input impedance: approx. 1 MΩ), or 4 to 20 mA (input impedance: approx. 250 Ω)
Flow rate output signal 0 to 5 V DC (load resistance 10 kΩ), or 4 to 20 mA (load resistance ≤ 500 Ω)
Digital communication Address setting with RS485 rotary switch or indicator: up to 99 devices (9600 bps)
Event input Three contact inputs (non-insulated)
Event output Three NPN open collectors (non-insulated, max. rating 35 V, 50 mA)
Required power supply (DC) +24 V DC (±10%), 300 mA max. (DC jack, D-sub)
Joint*6 1/4 F900 (standard), 1/4 UJR, Rc 1/4
Mounting posture Horizontal installation recommended.
Weight*7 Approx. 950 g Approx. 1100 g