Omron D6F Series User manual

MEMS Flow Sensor
MEMS Flow Sensor
User’s Manual
A286-E1-01
D6F-series

1 D6F-series MEMS Flaw Sensor User’s Manual (A286)
INDEX
1OUTLINE........................................................................................................................................ 2
2WHAT IS A FLOW SENSOR?....................................................................................................... 2
3STRUCTURE ................................................................................................................................. 2
3.1 BASIC COMPOSITION OF FLOW SENSORS.................................................................................... 2
3.2 FLOW SENSOR PRODUCT LINEUP .............................................................................................. 3
4OPERATING PRINCIPLE.............................................................................................................. 4
4.1 BASIC STRUCTURE OF MEMS FLOW SENSOR CHIP..................................................................... 4
4.2 DETECTING PRINCIPLE OF MASS FLOW SENSOR.......................................................................... 6
5PRODUCT FEATURES ................................................................................................................. 7
5.1 CHARACTERISTICS OF FLOW SENSORS ...................................................................................... 7
5.1.1 Detection range of flow sensors...................................................................................... 8
5.1.2 Output signal (operating characteristics)......................................................................... 8
5.1.3 Permission pressure performance .................................................................................. 9
5.1.4 Repeatability.................................................................................................................... 9
6USAGE OF FLOW SENSOR ........................................................................................................ 9
6.1 ELECTRICAL CONNECTION......................................................................................................... 9
6.2 PORT STYLE AND INSTALLATION METHOD.................................................................................. 10
6.2.1 Screw type..................................................................................................................... 10
6.2.2 Quick fastener type........................................................................................................ 10
6.2.3 Manifold mount type .......................................................................................................11
6.2.4 Bamboo type.................................................................................................................. 12
6.3 ATTENTION FOR PIPING AND CONNECTION ................................................................................ 13
6.3.1 Cleanup of the inflow gas .............................................................................................. 13
6.3.2 Stabilization.................................................................................................................... 13
6.3.3 Measurement of high flow ............................................................................................. 13
6.3.4 Consideration of the laminar flow.................................................................................. 14
6.4 THE INFLUENCE OF ENVIRONMENT ........................................................................................... 14
6.4.1 Temperature characteristics .......................................................................................... 15
6.4.2 The influence of dust ..................................................................................................... 15
6.4.3 The influence of pressure and temperature .................................................................. 16
6.4.4 The influence of the mounting direction ........................................................................ 16
6.4.5 Output changes in various gases.................................................................................. 17
6.4.6 The behavior in over flow rate range............................................................................. 17
6.4.7 The influence of humidity .............................................................................................. 17
6.5 APPLICATION EXAMPLE............................................................................................................ 18
7GLOSSARY ................................................................................................................................. 19
8WARRANTY AND LIMITED LIABILITY...................................................................................... 21

D6F-series MEMS Flaw Sensor User’s Manual (A286) 2
1 Outline
This application note explains the features, basic usage and some notices of OMRON MEMS
Flow Sensor (D6F series) before use.
2 What is a Flow Sensor?
A flow sensor is a sensor that detects the flow rate and flow velocity of a gas. In general, there are
various types of flow sensors, such as a propeller type, a float type, an ultrasonic type, a hot wire
type, and so on. OMRON flow sensors adopt a MEMS heat wire type, and have relatively excellent
characteristics in comparison with other types of flow sensors.
Table1. Various Types of Flow Sensor and Features
3 Structure
3.1 Basic composition of flow sensors
OMRON flow sensors are dedicated to gas, it can be used for detecting the mass flow of
various types of gases. The basic composition of flow sensors consist of a MEMS flow sensor
chip that can detect the flow rate, the amplifier circuit for amplifying sensor output and the
optimized flow path that is designed for each application by CAE (Computer Aided Engineering).
Optimizing these three compositions is very important because gas flow is a vector volume.
Type
Sensitivity
Response
Time
Pressure
Drop
Current
Consumption
Sensing
Size Element
Mechanical
Endurance
Propeller Float Ultrasonic Heat Wire MEMS
Heat Wire
OMRONConventional Sensors
Volumetric Flow Sensor Mass Flow Sensor
×
○
△
△
○
○
○
△
×
○
○
○
○
○
○
×
×
×
△
△
×
×
×
△
△
○
○
△
△
○

3 D6F-series MEMS Flaw Sensor User’s Manual (A286)
Fig. 1 Example of Internal Structure of Flow Sensor
3.2 Flow Sensor Product Lineup
OMRON’s flow sensor lineup consists of three categories, Mass flow sensors that output a flow
rate, Flow velocity sensors that output a flow velocity and Differential pressure sensors that can
detect a small pressure drop.
For more information about differential pressure sensors, please refer to the application notes of
MDMK-13-0196.
A flow sensor‘s shape and size will differ depending on the type of gas to be measured, the flow
rate, and the port style. Please refer to the datasheet at the following URL for more information.
http://www.omron.com/ecb/products/search/?cat=5&did=1&prd=mems-flow&lang=en
MEMS Flow Sensor
Mass Flow Sensor
Flow Velocity Sensor
D6F－V□/ －W□Series
D6F
－
PH Series
Differential Pressure Sensor
D6F
－□
A /
－□
AB /
－□
N /
－□
L /
－
P
□
Series
Driving / Amp. Circuit
MEMS
Flow Chip
Optimizing design of the three
compositional units is important.
Flow Path
(Sensing）(Heater / Output)

D6F-series MEMS Flaw Sensor User’s Manual (A286) 4
Table 2 Outline Specifications of D6F series
Series Name
Medium
Flow Rate Type Port Style Features
D6F-□A1 Air 1 ～2 lpm Mass Flow Bamboo Joint Compact Size
High Precision
Low Flow Rate
D6F-□N2 City gas*1 1 ～5 lpm Mass Flow Rc1/4 Screw Flammable Gas
Metal Body
D6F-02L2 LPG 2 lpm Mass Flow Rc1/4Screw Flammable Gas
Metal Body
D6F-03A Air 3 lpm Mass Flow M5 Screw High Response Time
D6F-□A5 Air 10 ～50 lpm Mass Flow Manifold Compact Size
High Flow Rate
D6F-□A6□ Air 10 ～50 lpm Mass Flow Rc1/4 Screw
NPT1/8 Screw
Compact Size
High Flow Rate
D6F-□□7 City gas*1
LPG / Air
2 ～50 lpm Mass Flow Quick Joint (P10) Quick Joint
D6F-□AB71 Air 30 ～70 lpm Mass Flow Quick Joint (P14) Quick Joint
Pulsation Reduction
D6F-P Air 0.1 ～1 lpm Mass Flow Bamboo / Manifold DSS*2 / Bidirectional
D6F-W Air 1 ～10 m/s Flow Velocity －DSS*2
D6F-V03A1 Air 3 m/s Flow Velocity －Low Cost of D6F-W
D6F-PH Air ±500 Pa Differential
Pressure
Bamboo Joint Digital Output
Differential Pressure
Note. *1 : City Gas (Natural Gas) Standard：13A, *2 : DSS: Dust Segregation System
D6F-A1 D6F-□N2/-02L2 D6F-03A D6F-□A5
D6F-□□6 D6F-□□7 D6F-□AB7
D6F-P D6F-W D6F-V03A1 D6F-PH
Fig. 2 D6F Series
4 Operating principle
4.1 Basic structure of MEMS flow sensor chip
The basic structure of a MEMS flow sensor chip is shown in Fig.3. This sensor chip adopts a

5 D6F-series MEMS Flaw Sensor User’s Manual (A286)
mass flow sensing method by using heat wire. It has a heater in the center of the chip, and the
upstream thermopile (A) and the downstream thermopile (B) are located on either side of the
heater, the base thermo-scope near the thermopile is made by a semiconductor process. The
cavity is formed at the bottom of the heater and the thermopile arrays, so then it is possible to
detect the heat from the heater effectively.
Fig.3. Flow Sensor Chip Structure
Base Thermo-scope
Downstream
Thermopile B
Upstream
Thermopile A
Heater
Thin film
Cavity
Contact pad
Heater
Contact pad
Downstream
Thermopile B
Contact Pad
Base thermoscope
Upstream
Thermopile A

D6F-series MEMS Flaw Sensor User’s Manual (A286) 6
4.2 Detecting principle of mass flow sensor
As shown in Fig.4, the constant current is flowing to the heater at the center of the chip and the
heater becomes hot. When there is no flow, the heat distribution around the heater is symmetric,
so Vu and Vd of the electromotive force from both thermopiles will be equal.
On the other hand, when there is a flow of gas on the sensor surface, the heat source is biased
on the downstream side according to the flow of gas. The electromotive force of the downstream
thermopile will be larger than the upstream thermopile (Vd > Vu). The output difference between
the two thermopiles is approximately proportional to the square root of the mass flow rate of the
gas through the sensor surface. The output sensitivity and the mass flow rate depend on the
composition ratio of the gas. Through amplification, it is possible to electronically detect the flow
rate of the gas. The flow velocity sensor is adjusted so that it can output a voltage that
corresponds to the flow velocity at the condition of 25℃, 101.3kPa from the mass flow rate.
When the flow direction is perpendicular to the thermopiles and heater.
Fig4. Sensing image of mass flow sensor using heat wire
Heat distribution in no flow condition
Vd＝Vu
The heat distribution is symmetric.
Vd
≠
Vu (Vd > Vu)
The downstream temperature is high
compare to the upstream temperature.
Heater
Downstream
Thermopile
Cavity
Vd
Vu
Heat distribution in flow condition
Vout = Voff +
（
Vd - Vu
）
× gain
Vout
：
Output voltage, Voff
：
Offset voltage
Vd-Vu
∝
√
(Flow rate)
Upstream
Thermopile
Flow Direction

7 D6F-series MEMS Flaw Sensor User’s Manual (A286)
5 Product Features
・Mass Flow Sensing
・Wide Range Sensing Ability
・Low Power Consumption
・Ultra Small Size of MEMS Sensor
5.1 Characteristics of flow sensors
Table3. Representative Specifications Example of Mass Flow Sensor (D6F-□□A1-110)
Type
Type D6F-01A1-110
Type D6F-02A1-110
Flow range＊1 0～1 L/min 0～2 L/min
Application medium
＊
2
Air
Port style
Bamboo Joint
Max Size
：
φ8.6mm , Min Size
：
φ7.4mm
Electrical connection
Connector (three wires)
Power supply voltage
DC10.8
～
26.4V
Current consumption
Max. 15mA, No load, Vcc=12
～
24V at 25
℃
Output signal DC1～5V (Non-linear output, Resistive load 10kΩ)
Accuracy
±3
％
F.S (at 25
℃
)
Repeatability
＊
3
±0.3
％
F.S.
Max. output voltage DC5.7V (Resistive load 10kΩ)
Min. output voltage
DC0V (Resistive load 10kΩ
）
Absolute maximum supply voltage
DC26.4V
Absolute maximum output voltage DC6V
Case material
PPS
Protecting structure
IP40 (IEC standard)
Maximum permission pressure
200kPa
Pressure drop
＊
3
0.42kPa
10.6kPa
Operating temperature
－
10
～＋
60
℃
(with no ice or no dew condensation)
Operating humidity
35
～
85
％
RH (with no dew condensation)
Storage temperature
－
40
～＋
80
℃
(with no ice or no dew condensation)
Storage humidity
35
～
85
％
RH (with no dew condensation)
Temperature characteristics Within ±3％F.S. of detected characteristics of at 25℃
Over ambient temperature rang －10～＋60℃
Insulation resistance
Min. 20MΩ (DC500, between lead terminal and the base)
Withstanding voltage
AC500V 50/60Hz for one minute between the lead terminals
and the base (Leakage current is 1mA max.)
Weight 12.8g
＊1. L/min (Normal) means the volumetric flow rate at 0degC, 101.3kPa. (1 atm)
＊2. Use clean and dry gas without a dust and an oil mist.
＊3. Reference Value (Typical value)

D6F-series MEMS Flaw Sensor User’s Manual (A286) 8
5.1.1 Detection range of flow sensors
The detection range of Flow Sensors shows the flow rate range of the gas to be detected.
The lower limit voltage is the output at the lower limit and the upper limit voltage is the output
at the upper limit of the detection range. This detection range is based on the condition of
the volumetric flow rate at the reference state (0 ℃/ 101.3kPa).
The detection range of Flow Velocity Sensors (D6F-W, D6F-V) shows the flow velocity range
of the gas to be detected. The lower limit voltage is the output at the lower limit and the
upper limit voltage is the output at the upper limit of the detection range. This flow velocity
range is based on the condition of 25 ℃, 1 01.3kPa.
5.1.2 Output signal (operating characteristics)
Analog type flow sensors increase the output signal voltage with an increase in the flow
rate. The output signal voltage is a non-linear and analog value of DC voltage. As a
representative example of an analog type flow sensor, the output characteristic of
D6F-01A1-110 is shown in Fig.5 and Table 4. This flow rate means a normal volumetric flow
rate on the condition of 0℃, 101.3kPa. These values are measured on the condition of
supply voltage:DC12V±0.1V, ambient temperature:25±5℃, ambient humidity: 35~75%RH.
Operating characteristics / Measurement conditions shown here will vary according to the
type of sensor. Please refer to the operating characteristic information written in the product
catalog or specifications corresponding to the sensor type.
Fig.5 Output signal characteristic
Table4. Representative Example of Operating Characteristics (D6F-01A1-110)
Flow Rate(normal)
(L/min)
0
0.2
0.4
0.6
0.8
1.0
Output Voltage (V) 1.00 2.31 3.21 3.93 4.51 5.00
Accuracy (V)
±0.12
±0.12
±0.12
±0.12
±0.12
±0.12
Condition：Supply voltage DC12±0.1V，Ambient temp. 25±5℃, Ambient humidity 35～75％RH

9 D6F-series MEMS Flaw Sensor User’s Manual (A286)
5.1.3 Permission pressure performance
When high pressure is impressed into a flow sensor, there is a concern about airproof
degradation. So, the maximum pressure that can be impressed to a flow sensor is defined
as Maximum Permission Pressure.
For example, the maximum permission pressure of D6F-01A1-110 is defined as 200kPa,
this means that airproof specifications and operating characteristic specifications after the
pressure test of 3 minutes at 200kPa are guaranteed.
Airproof is defined as the leak rate when a constant positive pressure is impressed to a flow
sensor. For example, D6F-01A1-110 guarantees that when the positive pressure of 100kPa
is impressed, the leak rate is 1x10-4 [Pa m3 / s] or less.
5.1.4 Repeatability
OMRON flow sensors have an excellent repeatability characteristic because they have a
unique flow path design which results in a stable gas flow. The repeatability is not
guaranteed but a reference value.
Fig.6 Repeatability characteristic Fig.7 Flow path design
6 Usage of Flow Sensor
6.1 Electrical Connection
The load resistance (Combined resistance seen from the flow sensor side) between the Vout
and GND terminals of the flow sensor should be 10kΩ or more. However, if you want to connect
a resistor (R1) between the voltage output terminal (Vout) of the flow sensor and the terminal to
detect the voltage (such as ADC input), please be mindful of the voltage drop by resistor (R1). In
general, it is recommended that R1 is less than 1/1000 (Less than 0.1% output voltage drop) of
the parallel resistance of R3 and R2 (R2||R3). Also be sure to check the cable resistance. If the
cable length is long, the resistance of the cable shall be deemed as R1.
Fig.8 Load resistance of the output line
R1
R2
R3
Vcc
Vout
GND
ADC etc.
MCU Board etc.
Flow
Sensor Load resistance : R1+R2||R3 ＞10kΩ
Voltage drop at R1 : ΔV = Vout×R1/(R1+R2||R3)