Gas flow sensor
Features
•
Solid State reliability
•
Low cost, small size
•
Long-term stability (parts of a percent)
•
Interchangeability (0.5%)
•
Protective polymer coating
•
Custom designs on request
Applications
•
Flow detection
•
Gas-flow measurements
•
Flow control
•
Absolute temperature measurement
•
Fluid detection
GFL-9722
Gas flow sensor
Description
The Gas Flow Sensor GFL-9722 is a ceramic based thermal sensor. It consists of two thick-film
heating resistors and a thick-film temperature sensor. Both temperature sensor and heating resis-
tors are laser trimmed which provides a true sensor-to-sensor interchangeability. The sensitive
parts of the sensor are coated with a black polymer, which protects them from harsh environments
like aggressive solvents, corrosive gasses and aggressive vapors.
When the GFL-9722 is heated by the heating resistors, a gas flow passing the sensor will cool it.
Because of this the output resistance will change. External temperature effects can be compensa-
ted using a second, not-heated, sensor connected in a Wheatstone bridge configuration.
Specifications
(in air, ambient temperature 20
o
C, 1 Atm.)
Parameter
Dimensions
Operating temperature
Storage temperature
Heating resistor
Typical heating voltage
Max. heating voltage
Temperature sensor
Stability
Sensitivity
Time constant
typ
7.5 x 7.5
-40 to + 70
-50 to + 170
50 ± 1
7
9
2000 ± 10
< 0.5
5.5 ± 0.5
3
units
mm
o
C
o
C
Ω
V
V
Ω
%
Ω/
o
C
sec.
notes
depending on flow and mounting
Xensor Integration
bv
copyright Xensor Integration
24 August 2005
Smart Sensor Devices
PO Box 3233
Distributieweg 28 Phone +31 (0)15-2578040 Founded 18 May 1988 ABN-AMRO 60 50 40 311
2601 DE Delft
2645 EJ Delfgauw Fax
+31 (0)15-2578050 Trade reg. 27227437 IBAN
NL42ABNA0605040311
www.xensor.nl
VAT NL 009122746 B01
The Netherlands The Netherlands Email
info@xensor.nl
Site
page 1 of 3
Gas flow sensor
Dimensions
GFL-9722
Positioning the sensor
The sensor is usually positioned parallel with
the gas stream:
•
in the heart of the stream (a).
•
protuding from the wall of the tube (b).
Front
7.62 mm (0.3”)
0.5 mm
a
tube
b
7.62 mm
(0.3”)
Front
10 mm
0.25 mm
(0.1”)
Heat + Out
Out
0.25 mm
(0.1”)
Heat
1.8 mm
Flow direction
3
1
2
Example of resistence response vs flow
Measurement in windtunnel by Mierij Meteo bv in de Bilt. GFL-9722 Sensor vertical parallel to
flow, connections down. Pressure: 1024 mBar, temperature: 300 K, heating voltage: 7.00 V.
Flow velocity
(m/s)
0
0.542
1.051
2.049
3.099
4.086
5.010
5.997
7.089
8.065
9.052
10.076
Temp sensor
(Ω)
2819
2625
2534
2455
2409
2379
2361
2343
2327
2317
2307
2292
ptc-resistance (Ohm)
2800
2600
2400
2200
0 1 2 3 4 5 6 7 8 9 10 11
flow velocity (m /s)
Xensor Integration
bv
copyright Xensor Integration
24 August 2005
Smart Sensor Devices
PO Box 3233
Distributieweg 28 Phone +31 (0)15-2578040 Founded 18 May 1988 ABN-AMRO 60 50 40 311
2601 DE Delft
2645 EJ Delfgauw Fax
+31 (0)15-2578050 Trade reg. 27227437 IBAN
NL42ABNA0605040311
www.xensor.nl
VAT NL 009122746 B01
The Netherlands The Netherlands Email
info@xensor.nl
Site
page 2 of 3
Gas flow sensor
GFL-9722
Application circuits: Temperature compensation
The following circuit can be used to compensate for temperature using the temperature reference
chip TD5 from Honeywell. This circuit is driven by a constant voltage source and gives an analog
output signal.
NB: there is a DC-offset on the output signal which must be compensated out.
The temp sensor is 2000
Ω
at 20ºC + 2750 ppm/K.
GFL-9722
Us 7V
4.99
kΩ
11.3
kΩ
U sensor
U comp
1
2
temp
sensor
3
50
Ω
heater
1
TD5
sensor
3
0V
Application circuits: Temperature compensation + read out
The following circuit can be used to read out the sensor.
GFL-9722
Us 7V
4.99
kΩ
11.3
U sensor
kΩ
1
TD5
sensor
3
0V
instr.
amp.
U comp
1
2
temp
sensor
3
50
Ω
heater
Conditions: Use of sensors for industrial applications is subjected to patent rights. Xensor Integration assumes no liability
arising from violation of these rights
Warranty: Xensor Integration warrants its products against defects in materials and workmanship for 12 months from
date of shipment. Products not subject to misuse will be replaced or repaired. The foregoing is in lieu of all
other expressed or implied warranties. Xensor Integration reserves the right to make changes to any product
herein and assumes no liability arising out of the application or use of any product or circuit described or
referenced herein.
Xensor Integration
bv
copyright Xensor Integration
24 August 2005
Smart Sensor Devices
PO Box 3233
Distributieweg 28 Phone +31 (0)15-2578040 Founded 18 May 1988 ABN-AMRO 60 50 40 311
2601 DE Delft
2645 EJ Delfgauw Fax
+31 (0)15-2578050 Trade reg. 27227437 IBAN
NL42ABNA0605040311
www.xensor.nl
VAT NL 009122746 B01
The Netherlands The Netherlands Email
info@xensor.nl
Site
page 3 of 3
京公网安备 11010802033920号
EEWORLD
