@2021 KITA Sensor Tech. Co., LTD. URL http://www.kita.com.tw
-44-
K F 0 2
Series
Instruction Manual
Thermal Mass Flow Sensor Principles
Pressure Loss Characteristics
6
Pressure Loss Characteristics
7
Thermal Mass Flow Sensor Principles
When flow begins, the inlet side
is cooled by the flow, the outlet
side is warmed by the heat of the
inlet side of the heater, and the
temperature distribution is like (b).
When the flow increases, it
becomes a distribution like (C).
Since the temperature distribution
before and after the heater is
proportional to the flow rate, the
flow rate can be determined from
the ratio.
In the absence of flow, the heat
from the heater spreads evenly
left and right, so the temperature
distribution is like (a).
Symmetric
Temperature Profile
No Flow
Skewed
Temperature Profile
Small Flow
Skewed
Temperature Profile
Large Flow
(a)
：
No Flow
(b)
：
Small Flow
(c)
：
Large Flow
Temperature
Sensor 1
Heating
Element
Temperature
Sensor 2
Temperature
Sensor 1
Heating
Element
Temperature
Sensor 2
Temperature
Sensor 1
Heating
Element
Temperature
Sensor 2
11
10
9
8
7
6
5
4
3
2
1
0
0 100 200 300 400 500
Flow Rate (L/min)
Pressure Loss (kPa)
0.2MPa
0.4MPa
0.6MPa
0 100 200 300 400 500 600 700 800 900 1000
Flow Rate (L/min)
60
50
40
30
20
10
0
Pressure Loss (kPa)
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Flow Rate (L/min)
100
90
80
70
60
50
40
30
20
10
0
Pressure Loss (kPa)
0.4MPa
0.6MPa
0.2MPa
0.4MPa
0.6MPa
●
KF02-501 (500 L/min)
●
KF02-202 (2000 L/min)
●
KF02-102 (1000 L/min)
