PFMB Digital flow switch with color display.

PFMB Digital flow switch with color display for air and nitrogen. Flow rate up to 1,000 l/min.

PFMB Digital flow switch with color display for air and nitrogen. Flow rate up to 1,000 l/min.
Measuring principle thermal hot wire
Measuring range from 2 to 1000 l/min
Output signal NPN; PNP; 1÷5V; 4÷20mA
Process connection 1/4"Gas - Fittings DN 8
Temperature up to 50°C
Pressure up to 8 bar
Degree of protection IP40 
Price from € 200,00

The flow sensors PFMB series are designed to measure the flow of fluids such as air and N2.
Their particularity is to have a color display to highlight an irregular value.
They display the accumulated flow and the flow rate.
Available with a valve for regulating the flow.
They are also suitable for horizontal, vertical and panel.

The chip of the MEMS sensor is constituted by a sensor for measuring the temperature upstream (Ru) and by a temperature sensor downstream (Rd), arranged symmetrically to the center of a platinum thin-film heater (Rh), mounted on a membrane and a sensor at room temperature (Ra) for measuring the temperature of the gas.
When the gas is static, the temperature distribution of the concentrated gas is uniform around Rh and Ru and Rd have the same resistance.
When the gas flows from the left side alters the balance of the temperature distribution of the gas and the resistor Rd becomes stronger than that of Ru.
The difference in resistance between Ru and Rd is proportional to the velocity of the gas. In this way the mensuration and analysis of resistance can show the direction of flow and the velocity of the gas. Ra appears to compensate for the gas and / or the ambient temperature.


  • Control of flow of N2 gas to prevent oxidation of the lead frame
  • Flow indication stored: it shows the operating range or the remaining amount (N2 etc.) in a gas cylinder
  • Suction control

Technical Characteristics

Measuring principle:
    • Thermal hot wire
    Measuring range / adjustment:
      • 2÷200 Lt/min | 5÷500 Lt/min | 10÷1000 Lt/min
      Outputs available:
        • 0÷10 [V]
        • 4÷20 [mA]
        • NPN/PNP
        Operating voltage [V]:
          • 12÷24 Vdc
          Precision Class:
            • ±2% VFS
            • ±5% VFS
            Operating temperature:
              • 0÷+50 [°C]
              Pressure max:
                • 0÷0.8 [MPa]
                Process connection:
                  • Rc 1/4" | NPT 1/4"| 1/4" Gas | Rc 1/2" | NPT 1/2"| 1/2" Gas
                  • Thread GAS
                  Materials in contact with the media:
                    • PPS
                    • Stainless steel AISI 304
                    • FKM
                    • Brass
                    Degree of protection:
                      • IP40
                        • UL approval
                        • Accredia certificate
                        • Calibration certificate
                        • RoHS certificate
                        • EC Declaration of Conformity