Type 8701

8 | 12

Visit product website 

5.

Performance specifications

5.1. Pressure loss diagram of MFMs

The diagram shows exemplarily the pressure loss characteristics when air flowing through. To determine the pressure loss of another

gas, it must first be converted to the corresponding air flow.

0

10

20

30

40

50

60

70

80

90

100

110

120

G1/4

Sub-base

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

Ql

N/min]

6.

Product operation

6.1. Measuring principle

The mass flow sensor operates according to a thermal principle which has the advantage of providing the mass flow which is inde-

pendent on pressure and temperature.

A small part of the total gas stream is diverted into a small, specifically designed bypassing channel which ensures laminar flow

conditions. The sensor element is a chip immersed into the wall of this flow channel. The chip, produced in MEMS technology,

contains a heating resistor and two temperature sensors (thermopiles) which are arranged symmetrically upstream and downstream

of the heater. The differential voltage of the thermopiles is a measure of the mass flow rate passing the flow sensor. The calibration

procedure effectuates a unique assignment of the sensor signal to the total flow rate through the device.