The calibration of Hygrometer (Lecture and Training Lecture and

The calibration of Hygrometer (Lecture and Training Lecture and

The calibration of Hygrometer
(Lecture and Training )
Japan Meteorological Agency
KAWAMURA HIROSHI
川村 裕志
1
Measurement methods
of Humidity(theory)
 Traceability and calibration methods
in JMA
ti )
 Calibration of Hygrometer (practice


About today’s practice
Place: the inspection room at 1st floor
2/35
1.1 Sorption methods（2types）
1.2 Psychrometric method
1 3 Condensation
C d
ti methods
th d （2types）
（2t
）
1.3
3/35
1.1 Sorption methods(1)
changes of the dimensions
hair hygrometer, hair hygrograph
1.1 Sorption methods(2)
changes of electrical properties
electronic hygrometer (capacitive type)
1.2 Psychrometric method
difference between the dry-bulb and wet-bulb
t
temperatureis
t i related
l t d to
t the
th ambient
bi t humidity
h idit
aspirated psychrometer
4/35
1.3 Condensation method(1)
equilibrium vapour pressure
at the surface of a salt solution
lithium chloride heated condensation
hygrometer
dewpoint
p
yg
1.3 Condensation method(2)
sense condensation
d
i with
i h an optical
i l detector
d
chilled-mirror dewpoint hygrometer
5/35
hair hygrograph
H i bundle
b dl
Hair
6/35
hair hygrograph
①Indicator adjusting screw
②Weight
③Main ccam
③
④Sub cam
⑤Rotation axis for main cam
⑥Rotation axis for sub cam
⑦Plate attaching sensor part
of humidity
⑧Screw attaching sub cam
⑨Connecting spring
⑩lever
⑪Hair bundle
Structure of hair hygrograph
7/35
electronic hygrometer(capacitive type)
converter
sensor
probe
b
sensor
filter
8/35
electronic hygrometer(capacitive type)
upper
electrode
upper electrode
(high-porosity)
polymer
membrane
bottom
electrode
glass plate
9/35
electronic hygrometer(capacitive type)
upper
electrode
upper electrode
(high-porosity)
l
polymer
membrane
bottom
electrode
glass plate
10/35
electronic hygrometer(capacitive type)
H2O
upper
electrode
upper electrode
(high-porosity)
l
polymer
membrane
bottom
electrode
glass plate
11/35
electronic hygrometer(capacitive type)
changes
h
in
i capacitive
iti between
b t
electrodes
l t d
（low humidity)
（high humidity)
12/35
aspirated psychrometer
JMA type
Assuman type
wet-bulb
dry-bulb
13/35
14/35
lithium chloride heated condensation
dewpoint
p
hygrometer
yg
（（dew cell))
resistance thermometer
wire as electrodes
humidity-sensitive part
・An operational equilibrium temperature exists for the instrument,
depending upon the ambient water-vapour pressure. At the equilibrium
temperature,neither evaporation nor condensation occurs because the
equilibrium vapour pressure and the ambient vapour pressure are equal.
15/35
chilled-mirror dewpoint hygrometer
感部
・ measurement of Td or Tf .
・ small polished-metal reflecting surface cooled
electrically by using a Peltier-effect device sense
condensation with an optical detector.・
16/35
17/35
Temperature,
p
,
Humidity,
Pressure, ・・・
(Without radiation)
Traceability chart of JMA
International Standard
(SI unit)
National Primary Standard
(National Metrology Institute of Japan)
JMA
National meteorological standard
(JMA standard)
Working
W
ki standards
d d
(JMA sub-standard)
(
)
MIC(RIC)
Working instruments
(Observation sites)
18/35
Traceability of Humidity (JMA)
National Primary
Standard
National Metrology
Institute of Japan
Standard humidity
generator set
Calibration
： every year
JMA Standard
Working Standard
Meteorological Instruments Center
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (display)
DewStar S-1M-0
(Shinyei technology, Japan)
Hygrometer (sensor)
DewStar S-2S-0K
S 2S 0K
(Shinyei technology, Japan)
Feb. 2012 by JMA
Field Instruments
Observatory
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (controller)
Hygro M2
(General Eastern, USA)
Hygrometer (sensor)
D2
(General Eastern, USA)
Electronic hygrometer
Calibration
： every year
Filter change:
Every 6 months
Check：
・every 3 months
(manned observatory)
・every year (automatic
weather station)
Tolerable range：±4%
Aspirated
psychrometer
Lithium chloride
dewpoint hygrometer
Check：
at the time
of installation
JMA Standard of
thermometer
Mercury-in-glass
thermometer
(Assuman type
19/35
psychrometer)
Sensor unit
Monitor
Chilled-mirror dewpoint hygrometer
20/35
JMA Standard
DT 12.3 ℃
Humidity
H idit generator
g
r t r
(Wet and dry air mixing type)
DT 12.6
12 6 ℃
W ki
St d d
Working
Standard
Fl
dj t
：Flow
adjuster
21/35
22/35
Traceability of Humidity (JMA)
National Primary
Standard
National Metrology
Institute of Japan
Standard humidity
generator set
Calibration
： every year
JMA Standard
Working Standard
Meteorological Instruments Center
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (display)
DewStar S-1M-0
(Shinyei technology, Japan)
Hygrometer (sensor)
DewStar S-2S-0K
S 2S 0K
(Shinyei technology, Japan)
Feb. 2012 by JMA
Field Instruments
Observatory
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (controller)
Hygro M2
(General Eastern, USA)
Hygrometer (sensor)
D2
(General Eastern, USA)
Electronic hygrometer
Calibration
： every year
Filter change:
Every 6 months
Check：
・every 3 months
(manned observatory)
・every year (automatic
weather station)
Tolerable range：±4%
Aspirated
psychrometer
Lithium chloride
dewpoint hygrometer
Check：
at the time
of installation
JMA Standard of
thermometer
Mercury-in-glass
thermometer
(Assuman type
23/35
psychrometer)
chamber(constant-temperature)
p
H 76.5％RH
Humidity generator
(Wet and dry air mixing type)
Field Instruments
（Electronic hygrometer）
Working Standard
Thermometer
Working Standard
DT 12.5 ℃
Pump
T
23.0 ℃
24/35
Traceability of Humidity (JMA)
National Primary
Standard
National Metrology
Institute of Japan
Standard humidity
generator set
Calibration
： every year
JMA Standard
Working Standard
Meteorological Instruments Center
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (display)
DewStar S-1M-0
(Shinyei technology, Japan)
Hygrometer (sensor)
DewStar S-2S-0K
S 2S 0K
(Shinyei technology, Japan)
Feb. 2012 by JMA
Field Instruments
Observatory
Chilled-mirror dewpoint
p
hygrometer
Hygrometer (controller)
Hygro M2
(General Eastern, USA)
Hygrometer (sensor)
D2
(General Eastern, USA)
Electronic hygrometer
Calibration
： every year
Filter change:
Every 6 months
Check：
・every 3 months
(manned observatory)
・every year (automatic
weather station)
Tolerable range：±4%
Aspirated
psychrometer
Lithium chloride
dewpoint hygrometer
Check：
at the time
of installation
JMA Standard of
thermometer
Mercury-in-glass
thermometer
(Assuman type
psychrometer)
26/35
Thermometer
Hygrometer
Air flow
27/35
28/35

Comparisons against a reference instrument

Standard Calibration



Relative humidity
ex) 20[％],40[％] ,60[％] ,80[％] ,95[％]
at 23[℃]±3[℃]
Dew point temperature
ex) -5[℃] ,0[℃] ,5[℃] ,10[℃] ,15[℃] ,20[℃] ,25[℃]
under suitable steady conditions

Humidity chamber




Dynamic two-pressure humidity generator
Wet and dry air mixed-flow generator （MIC using）
etc.
Saturated salt solutions
29/35
constant-temperature bath
controlled by liquid circulator
Saturation
tank
Dry air
Chamber
Flow controller
[diagram of system]
30/35
Vessels containing saturated solutions of appropriate
salts mayy be used to calibrate relative humidityy
sensors.
Barium chloride (BaCl2): 90.3 ％
Sodium chloride (NaCl)
(NaCl):
75.3 ％
Magnesium nitrate (Mg(NO3)2): 52.9 ％
Calcium chloride (CaCl2): 29.0 ％
Lithium chloride (LiCl)
(LiCl): 11.1 ％
etc.
at
25°C
31/35
ex） Vaisala HMK15
Refer to User Guide
32/35
Comparisons against a reference instrument
under
d the
th room
Purpose: Check the difference between the Hygrometers.
Reference Hygrometer:
“Chilled-mirror dewpoint hygrometer“
“Platinum resistance thermometer“
Hygrometer１:“Electronic hygrometer“
Hygrometer２: “Hair hygrograph“
Hygrometer３:“Aspirated psychrometer“
Demonstrations：Chilled-mirror dewpoint hygrometer setting
Saturated salt solutions(NaCl) setting
Group A;
Bangladesh
Cambodia
Lao PDR
Maldives
Mongolia
Myanmar
Nepal
For Group A
For Group B
Hygrometer
1,2,3
And
Reference
Hygrometer
1,2,3
And
Reference
※ 1st floor
Calibbration
chaamber
Calibration chambers
Group B;
Oman
Pakistan
Qatar
Sri Lanka
Th il d
Thailand
Viet Nam
34/35
Example (Group A)
Dewpoint temperature
1st
The time of
reading
No.
1
2
3
4
5
6
7
Reference(HYGRO M-2)
(Example)
Bangladesh
Cambodia
Laos
Maldives
Mongolia
Myanmar
Nepal
hh:mm
15:00
：
：
：
：
：
：
：
The value of
correction
reading
[℃]
-5.9
①
[℃]
The value of
correction
reading
1
2
3
4
5
6
7
(Example)
Bangladesh
Cambodia
Laos
Maldives
Mongolia
Myanmar
Nepal
-
[℃]
10.9
vapour
pressure in
air ※1
corrected
value
[℃]
Reference　(F-250)
[℃]
Saturation
vapour
pressure※1
The value of
corrected
correction
reading
value
[hPa]
[℃]
22.225
[℃]
②
Wet Bulb
No.
Air temperature
[℃]
[hPa]
Relative
humidity[B]
Reference
value
[%RH]
③
p
ppsychrometer
y
Aspirated
Dry Bulb
⑥
corrected
value(T)
The value of
reading
[℃]
[℃]
22.5
⑦
Calibrated
Hygrometer's
reading value
Electronic
hygrometer
[%RH]
14.31
Hair
hygrometer
[%RH]
21
④⑤
correction
corrected
value(Tw）
T-Tw
[℃]
[℃]
[℃]
Atmospheric
pressure
[hPa]
1009.80
Relative
⑧humidity※2
[%RH]
-
Please pass the staff after finished.
Please
read twice
(①→⑧
①→⑧)
36/35