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

  Another Article:


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.)
 Air, N2
Flow range*2 10 SCCM to 10 SLM 20 to 50 SLM
(20 to 30 SLM for CO2)
100, 150 SLM 200, 300 SLM
Control range 2 to 100% (F.S.) 5 to 100% (F.S.)
Response*3 Total 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
Repeatability ±0.25%F.S. ±0.5%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 kPa 200 SLM: 200 to 350 kPa
300 SLM: 250 to 350 kPa
Inlet maximum pressure 500kPa(G)
Proof pressure 980kPa(G)
External leak rate ≤1.0 x 10-8 Pa·m3/sec (He) ≤1.0 x 10-7 Pa·m3/sec (He)
Temperature Working temp. 5 to 50℃
guaranteed temp.
15 to 35℃
storage temp.
-10 to 60℃
Allowable operating humidity 10 to 90% RH (without dew condensation)
Materials of gas contact part SUS316, SUS316L, magnetic stainless steel, Ni, PTFE, PCTFE, and FKM
Electrical connection D-sub 9-pin, KFC standard (SEMI standard compliant), RJ-45 modular jacks (two) D-sub 9-pin ,
HR-10A (two)
Flow rate setting signal 0 to 5 V DC (input impedance: approx. 1 MΩ)
Flow rate output signal 0 to 5 V DC (load resistance 10 kΩ)
Digital communication Address 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*6 1/4 F900 (standard), 1/4 UJR, Rc 1/4 1/2 SW (standard), 3/4 SW
Mounting posture Horizontal installation recommended.
Weight*7 Approx. 850 g Approx. 1000 g Approx. 2250 g Approx. 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

for more information and price please contact marketing@wmablog.com

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