Kofloc DF-250C Series Digital Mass Flow Meter

 The DF-250 series is a high-performance digital mass flow controller with ≤1 sec response less than 50SLM specification. The series offers a large flow rate line-up up to 300SLM.


  • Standard gases are calibrated with actual gas
  • ~50SLM model offers a fast response of ≤1 sec
  • 10sccm ~ 300SLM flow range line-up
  • Communications functions installed as a standard feature(RS485)
  • RoHS/CE Standard compliant

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Sensor typeThermal sensor
Valve typeNormally closed proportional solenoid valve
Applicable gases*1N2, Air, H2, He, Ar, O2, CO2, etc.
(Gases not specifically mentioned here are subject
to calibration for N2 equivalent.)
 Air, N2
Flow range*210 SCCM to 10 SLM20 to 50 SLM
(20 to 30 SLM for CO2)
100, 150 SLM200, 300 SLM
Control range2 to 100% (F.S.)5 to 100% (F.S.)
Response*3Total flow rate control range ≤ 1 sec (within ±2% F.S.)≤  1.5 sec / ≤ 3 sec less than 10%
(within ±2% F.S.)
≤  2 sec (within ±2% F.S.)
Accuracy*4±1.0% F.S.±2.0% F.S
Operating differential
50 to 300 kPa
(100 to 300 kPa for Ar and CO2)
100 to 300 kPa
(150 to 300 kPa for Ar and CO2)
150 to 350 kPa200 SLM: 200 to 350 kPa
300 SLM: 250 to 350 kPa
Inlet maximum pressure500kPa(G)
Proof pressure980kPa(G)
External leak rate≤1.0 x 10-8 Pa·m3/sec (He)≤1.0 x 10-7 Pa·m3/sec (He)
TemperatureWorking temp.5 to 50℃
guaranteed temp.
15 to 35℃
storage temp.
-10 to 60℃
Allowable operating humidity10 to 90% RH (without dew condensation)
Materials of gas contact partSUS316, SUS316L, magnetic stainless steel, Ni, PTFE, PCTFE, and FKM
Electrical connectionD-sub 9-pin, KFC standard (SEMI standard compliant), RJ-45 modular jacks (two)D-sub 9-pin ,
HR-10A (two)
Flow rate setting signal0 to 5 V DC (input impedance: approx. 1 MΩ)
Flow rate output signal0 to 5 V DC (load resistance 10 kΩ)
Digital communicationAddress setting with RS485 rotary switch: up to 99 devices (9600 bps)
Required power supply (DC)+15 V DC (±5%) : 150 mA
-15 V DC (±5%) : 150 mA
+15 V DC (±5%) : 150 mA
-15 V DC (±5%) : 250 mA
24 V DC (±10%) : 450 mA
Joint*61/4 F900 (standard), 1/4 UJR, Rc 1/41/2 SW (standard), 3/4 SW
Mounting postureHorizontal installation recommended.
Weight*7Approx. 850 gApprox. 1000 gApprox. 2250 gApprox. 3500 g

*1 The gases must be dry and clean, free of corrosive components and foreign matter such as dust and mist.

*2 Dedicated software is available to change gases or change the actual full scale (F.S.) within the range of 30 to 100% (30 to 80% for CO2 only) of the specified full scale.

*3 The flow rate calibration units SCCM and SLM indicate a mass flow rate converted to a volume flow rate in cc/min and L/min at 0°C and 1 atm.

*4 Guarantee for calibration gas: N2.

*5 Accuracy for calibration gas: N2, flow range (max. full scale).

*6 The operating differential pressure may differ depending on specifications.

*7 Contact us for any other joints.

*8 Exclusive of the weight of joint