SATO KEIRYOKI SK-5RAD-SP User manual

Instruction Manual for
No. 7435-00 Multiple Measuring System
Model SK-5RAD-SP
No. 3 Nishi-Fukudacho, Kanda, Chiyodaku, Tokyo 101-0037 Japan
URL: http://www.sksato.co.jp/english/
02.07

1
Thank you for purchasing the multiple measuring system model SK-5RAD-SP.
- This product is designed to measure dry bulb and wet bulb temperatures, relative humidity.
dew point temperature and absolute humidity. Do not use it for other purposes.
- Read this manual carefully before using. Keep the manual in a safe place for future
reference whenever necessary.
Warning
The SK-5RAD-SP is not explosion-proof. Never use it in an atmosphere containing flammable
gases.
Beware of explosion!
There is a risk of explosion. Take extreme care.
Features
(1) Direct reading is possible.
Relative humidity, dew point temperature and absolute humidity readings are indicated.
Any calculation or conversion table is not required.
(2) Easy-to-read bright digital display
The large display makes the values easy to read, and the data (values) can be checked
even from a distance
(3) No deterioration with time
The instrument will not deteriorate with time since it is not influenced by ambient gases for
measurement,
(4) Provides outputs
Data for dry bulb temperature and relative humidity can be taken in analog voltage (0 to
1VDC).
Its application is wide, connection to a recorder to give an example.
(5) Possible remote measurement (standard cable length: 10m)
The display unit and the sensor unit can be placed separately. It is possible to extend the
cable up to 50m at option.
(6) Error message display function
The system is equipped with self-diagnosis capabilities to prevent incorrect operating
procedures and accidents. If data or any function is found to be abnormal, an error
message is displayed in the relative humidity display section.

2
Name of Each Part
* Measured values for current dry-bulb and wet-bulb temperatures are indicated.
* Operated values for relative humidity, absolute humidity and dew point temperature are
indicated.
* If extraordinary value is found in a data etc. under measurement, error message will be
indicated in the display section of relative humidity.
(1) Display Unit
Front view Rear view
(2) Sensor Unit
1. Display section 6. Fuse (2A)
2. Case 7. Power switch
3. Control knob 8. Terminal for analog output (temperature)
4. Stand (handle) 9. Terminal for analog output (R.H.)
5. Connector for AC line 10. Receptacle for the sensor cable
11. Hanging ring 17. Air intake tube for dry bulb
12. Connection cable 18. Air intake tube for wet bulb (upper part)
13. PT sensor (inside of intake tube) 19. Hook
14. Stand fastener 20. Air intake tube for wet bulb (lower part)
15. Reservoir holder 21. Hook for mount
16. Water reservoir

3
Water
supply
bottle
Fill water
four-fifths
full
Water
reservoir
Operation method
(1) Inspection
When shipment is first received, check the appearance and confirm the accessories
attached.
(2) Storage
When the instrument is not used for a long period of time, discard remaining water in
feed water tank, put a dust cover on it and keep it at a place free from damp, dusts and
direct sunlight. The storage temperature is 0 to 50℃and humidity is lower than 85%rh.
(3) Wiring
a. Connecting sensor unit and display unit
Insert the connection cable plug into the sensor cable connection port (socket) on the
display unit. Align the socket with the plug carefully and insert the plug fully. Use a
coupling nut to fasten the tightly.
b. Connecting the power cable
Make sure that the power switch is in the OFF position before inserting the attached
AC power cable into the AC power cable connection port.
c. Connecting other cables
Before connecting output cables (optional parts), check the respective output
terminals. Never apply a voltage to the output terminals.
(4) Fastening of the sensor unit
Mount the unit by using either the stand or the hanging ring on
the top. The unit may also be suspended from a tripod (option).
NB. Do not hold the unit in your hands while measuring.
(5) Placing the display unit
The display unit is designed to be installed anywhere. It can be carried hung, fixed in
place, or suspended as necessary with ease. The angle of tilt can be adjusted by rotating
the control knob for optimum viewing of the display unit
(6) Water supply
a. Carefully pull the string from the guide above the water reservoir.
NB. Thoroughly wash your hands or use forceps
when removing wick. This reduces the
build-up of salts and acids on the wick.
b. Fill the water reservoir to four-fifths with distilled water, using
the water bottle supplied. Ordinary tap water should be
avoided because it affects the accuracy of the measurements.
Be sure that the inside of the air intake tube stays dry.
Moisture on the walls of the intake tube will cause
lower-than-normal wet bulb temperature.
Stand
fastener
stand
Air intake clamp
String
Water reservoir

4
(7) Operation
a. Place the power switch on the front of the instrument in ON position. The ventilation
fan will begin to turn. Display will appear in about three seconds.
b. Warm up the instrument for at least five minutes after it is turned on. This warming up
should be performed longer when the instrument is moved to a place with different
circumstances, viz. from a room with temperature of 20℃to a room with temperature
40℃. It is necessary to condition the instrument thermally with ambient atmosphere.
c. Measurement will be possible when the indicated value of dry-bulb temperature and
wet-bulb temperature come to stabilize.
d. If the instrument is stabilized once, measurement can be done almost in real time
against the change of circumstances. However, there may be delay in time against the
sudden change of circumstances.
e. Sampling time is three seconds. Each value on the display will change every 3
seconds.
f. Be sure to place power switch in OFF position when measurement is suspended or
over.
(8) Connecting analog outputs with other instruments
a. Connection
Analog outputs for temperature and humidity can be created by using the terminal
block located at the back of the unit. See the figure below for details of the wiring.
b. On output under measurement
Temperature: display will change every three seconds, but output will change in real
time.
temperature
time
Relative humidity: Both display and output will change every three seconds.
humidity
timetime
* For principles, refer to the block diagram at page 9.
dry bulb temperature:
: 0 to 50°C / 0 to 1VDC
relative humidity:
: 0 to 100% / 0 to 1VDC
displa
y
output
display and output

5
c. Application of data output
Continuous measurement of recording is possible in connecting with the recorder.
Recorder
10m
humidity
0 to 1VDC
temperature
0 to 1VDC
Connection cable

6
Maintenance
(1) Replacing the wick
Before using the instrument, make sure the wick is free from dust and dirt. Replace
the wick if it is dirty. Replace wick and distilled water once every seven days.
Be sure your hands are clean when replacing the wick.
a. Remove the water reservoir.
b. Pull horizontally the air intake clamp, and pull
down the air intake tube.
c. Pull down the old wet bulb wick and clean
the sensing part (at 30 mm from the top of
PT sensor) with clean, dry cloth.
d. Use forceps to attach a wick to the sensing part.
e. Don’t let the string get stuck or caught
between the housing and air intake tube,
between the clamp and air intake tube or
in the grooves.
Join the upper and lower sections of the
air intake tube and lock with the clamp.
N.B. Carefully connect the clamp tabs with
the groove on the upper part of the air
intake tube.
f. Reattach the water reservoir to the reservoir
holder, and place the string into the reservoir.
Air intake tube
(upper part)
Groove
for clamp
Air intake
tube
(lower part)
Clamp tabs
String guide
Hole for
string
Clamp
Air intake tube
(lower part)
String
Grooves
Air intake tube
(upper part)
Air intake tube
(upper part)
Sensor
Wet bulb wick
Groove for
string
Install the wick by
aligning the string with
the groove for string.
Air intake tube
(upper part)
Air intake tube
(lower part)
Old wick
Air intake clamp
Water reservoir
String

7
(2) Using gauze as the wet bulb wick
Using gauze is an alternative to using the standard wicks when more accurate
measurement is required at the state of lower than 25%RH.
a. Remove the old wick as shown in (1) “Replacing the wick”on
page 6.
b. Use gauze and a thread made of cotton fiber.
We do not recommend a synthetic fiber. Boil the gauze and
cotton thread in soapy water, rinse the materials with distilled
water to remove soap residues and oils.
c. Cut a piece of gauze large enough to fit around the bulb (100 x 15 mm), and dampen it
with distilled water. Extend the gauze about 10mm from the end of the bulb, and wind the
gauze around the sensing part without making wrinkles.
d. Use cotton thread to tie the gauze firmly around the
sensing part.
e. Tie of the end of the gauze with another piece of tread.
The knot should be snug.
f. Cut off the gauze about 2 or 3 mm beyond the end of
the sensing part.
g. Carefully pull out and remove the horizontal threads
(woofs) of gauze above the hollow of the sensing part,
leaving only the vertical strands (warps). Make a string
by binding the remaining wraps of gauze.
h. Follow steps 5 and 6 in “Replacing Wick”. Replace the lower part of air intake pipe, clamp,
water reservoir, and insert the string into the water reservoir.
Use cotton thread
to the gauze firmly
Tie off the end of
the gauze
Cut off the gauze
Make a string by
binding the
remaining warps
Knot
above
bulb
Bulb

8
Explanation of Each Error Message
Cautions
(1) On interval of water supply
Duration of continuous operation with a supply of water differs depending on the
circumstances where the instrument is used. Be careful about water level of feed water
tank referring to the following (table 1). The chart is given just for criteria.
Display
Contents
Causes and countermeasures
Dry bulb or wet bulb temperature
has fallen below 0℃
*Exceeds the conditions for use. Use it at
temperature of higher than 0℃
Dry bulb or wet bulb temperature
has risen to more than 51℃
*Exceeds the conditions for use. Use it at
temperature of lower the 50℃
Operation result of relative humidity
has become less than 0% RH
*Operation function may be abnormal.
*Turn off power switch and turn on again.
*There will be something wrong with the
instrument if it is not restored.
Consult us.
Operation result of relative humidity
has become more than 100%R.H.
*Wet bulb temperature is higher than dry bulb
temperature.
*Check with water level of feed water tank and
check if wet bulb paper string contains water
or not. There is a possibility that this may
occur in atmosphere where the relative
humidity is over saturated.
It is because the instrument is used beyond
the conditions for use.
Operation result of dew point has
become lower than -41℃
*Exceeds the display range for dew point.
When capacity of battery is not
enough or power source is less
than 90VAC.
*Charge the exclusive battery.
Use the instrument at 100VAC±10%
Lower than 40% R.H.
Higher than 40% R.H.
Lower than 15℃
about 20 hours
about 30 hours
15 - 35℃
about 25 hours
about 35 hours
35 -50℃
about 15 hours
about 20 hours

9
(2) On measuring range for continuous measurement and measuring area
Part and are areas where measurement is
possible.
Part is an area where continuous measurement is
possible.
Part is an area where a short time measurement is
possible.
Principles of Operation
When the sensor section of thermometer is wrapped with a gauze which is dampened
with water, the temperature of the sensing sensor will fall. The latent heat of evaporation
of water at this time has a definite relation with vapor pressure and therefore relative
humidity etc. can be calculated by formula.
The instruments uses platinum resistance temperature detector which has stable
accuracy for a long period of time for the temperature measurement of dry bulb and wet
bulb and uses the latest CPU in its operation section to operate with high precision.
%RH
100
90
80
70
60
50
40
30
20
10
0
10
20
30
40
50 ℃
R/V
converter
A/D
converter
dry bulb
temperature
wet bulb
temperature
CPU
relative humidity
D/A converter
dew point
absolute humidity
0～1V DC
0～1V DC

10
Specifications
Cat. No.
7435-00
Model
SK-5RAD-SP
Elements
Dry Bulb
Temperature
Wet Bulb
Temperature
Relative
Humidity
Dew Point
Temperature
Absolute
Humidity
Display
7 segment red LED 3 digits
7 segment
red LED
2 digits
Measuring Range
0 to 50.0°C
---
Operation Range
---
0 to 99.9%rh
-40 to 50.0°C
0 to 83g/m³
Resolution
0.1°C
0.1%rh
-40 to -10°C
: 1°C
-9.9 to 50°C
: 0.1°C
1g/m³
Measurement
Accuracy
within ±0.2% F.S.
---
Operation Accuracy
---
within ±0.01%
Indication Accuracy
0.2% F.S. ±1 digit
1% ±1 digit
0.1°C ±1 digit
within 1%
Sampling Time
about 3 seconds
Detective Sensors
Pt100
---
Output
0 to 50°C /
0 to 1VDC
---
0 to 100% /
0 to 1VDC
---
Output Impedance
500Ω
---
500Ω
---
Air-flow Speed
more than 3m/s at an outlet
or air-flow
---
Operating Ambient
Temperature : 0 to 50°C (no freezing of wet bulb)
Humidity : less than 85% (no condensing)
Power Requirements
100VAC ±10% 50/60Hz
Power Consumption
100mA
Outer Dimensions
Display unit : 311 (W) × 192.5(H) × 144 (D) mm
Sensor unit : 80 (W) × 264 (H) × 110 (D) mm
Weight
Display unit: about 4.5kg Sensor unit: about 1.5kg (including the cable)
Standard Accessories
Power cable (2 m), wicks (20 pcs.), water supply bottle, exclusive stand, test
result

No. 3 Nishi-Fukudacho, Kanda, Chiyodaku, Tokyo 101-0037 Japan
URL: http://www.sksato.co.jp/english