Global Water
800-876-1172 • globalw.com
00-671
Publication Number 38320112
Global Water
Instrumentation, Inc.
151 Graham Road
P.O. Box 9010
College Station, TX 77842-9010
T: 800-876-1172
Int’l: (979) 690-5560, F: (979) 690-0440
Barometric Pressure: WE100
Solar Radiation: WE300
Wind Speed: WE550
Wind Direction: WE570
Humidity: WE600
Temperature Sensor: WE700
Solar Shield: WE770
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Global Water
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Congratulations on your purchase of the Glob al Water Weather Sensor. This
instrument has been quality tested and approved for providing accurate and
reliable measurements. We are confi dent that you will find the sensor to be a
valuable asset for your application. Should you require assistance, our
technical staff wil l be ha ppy to help.
Table of Contents
I. Checklist
• • • • • • • Page 3
II. Inspection
• • • • • • 3
III. General Sensor Installation
• • • • 4
IV. Barometric Pressure Sensor
• • • • 5
V. Solar Radiation Sensor
• • • • • 7
VI. Wind Speed Sensor
• • • • • 8
VII. Wind Direction Sensor
• • • • • 9
VIII. Humidity Sensor
• • • • • • 10
IX. Temperature Sensor
• • • • • 11
X. Solar Shield
• • • • • • 12
XI. Maintenance
• • • • • • 12
XII. Troubleshooting
• • • • • • 13
XIII. Warranty
• • • • • • • 15
XIV. Appendix A: Temperature Calibration Check
• • 16
XV. Appendix B: 2 Wire Sensor Measurement Diagr am
• 17
XVI. Appendix C: 3 Wire Sensor Measurement Diagram
* Copyright Global Water Instrumentation, Inc. 2002
• 18
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I. Sensor Checklist
a. Weather Sensor
b. Weather Sensor Manual
II. Inspection
a. Your Weather sensor was carefully inspec ted and certified by our
Quality Assurance Team before shipping. If any damage has occurred
during shipping, please notify Global Water Instrumentation, I nc . and
file a claim with the carrier involved.
Use the checklist to ensure that you hav e r ec eived every thing needed
to operate the weather instrument( s ) .
Global Water
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III. Genera l Sensor Installation
a. Weather sensors have many applications and ther efore many
installation options. The sensors s hould be loc ated in a clear area on
a level surface.
b. Install your Weather sensor so t hat it is easily accessible for calibration
purposes. You may need to remove and reinstall it in the future, so
plan ahead!
c. All G lobal Water Weather sensors produce a 4-20 mA output signal.
4-20 mA is an industrial standard signal for proc ess control monitoring.
Most PLCs (Programmable Logic Controller) , RTUs (Remote
Telemetry Unit), and data acquisition s y s tems accept this signal
directly. If the system only accepts volt age s ignals , the sensor output
must be converted to a voltage signal by reading t he v oltage across a
precision resistor in series with t he s ignal wir e. Since Ohms Law
states that V = IR, if the 4-20 mA signal is dropped across a 250 ohm
resistor, the output will be 1 to 5 volt s DC. If the 4-20 mA signal is
dropped across a 125 ohm resistor, the out put will be halved to 0.5 to
2.5 VDC. The 4-20 signal wire is connected to the datalogger v oltage
input terminal. The resistor is plac ed between this input and the
ground terminal of the datalogger’s bat tery. The power (or voltage to
the sensor) must be connected to positive bat tery terminal of the
datalogger.
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d. The sensors may be pulsed on or turned on by the logging sys tem
prior to taking a reading. Use a warm up time appropriate to t he
Weather sensor you are using to assure t hat t he sensor is fully on.
The sensors can run continuously for real t im e applications . Each
sensor draws between 4 and 20 mA depending on whether the sensor
is reading at the minimum or maximum of its r ange.
e. Weather sensors may be stored without any s pecial provis ions . Place
the sensor inside a bag to keep the sensor clean and stor e on a s helf
or hang it on a wall.
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IV. Barometr ic P r essure Sensor
a. Barometric Pressure sensor specifications.
Output: 4-19mA
Range: 800-1100 mill ibars
Accuracy: +1% of full scale
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temperature: -40° to +55°C
Size of Probe: 3”x2”x1”
Weight: .13 lb.
b. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.
c. The bar om etric pressure sensor may be stored without any s pec ial
provisions. Place the sensor inside a bag to keep t he s ens or c lean
and store on a shelf or hang it on a wall.
d. When you read a barometer the reading direct ly from it is the "station
pressure."
Two things affect the barometer's r eading, the high or low air pressure
caused by weather systems, and the air pressure caused by the
station's elevation, or how high it is abov e s ea lev el. No matter what
weather systems are doing, the air's pr es s ur e decreases with height. If
you're trying to draw a weather map of air pressure patterns, you need
a way to remove the effects of the station's elevation. That is, you want
to see what the pressure would be at the st ation if it were at sea level.
You need to calculate, sea-level pressure, which is defined as: "A
pressure value obtained by the theoretical reduction of barometric
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Global Water
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pressure to sea level. Where the Earth's s ur face is above sea level, it
is assumed that the atmosphere extends to s ea level below t he s tation
and that the properties of that hypothetical atmosphere are related to
conditions observed at the station." To do t his , you have to take into
account the barometric reading at the station, the elevation above sea
level, and the temperature.
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V. Solar Radiation Sensor
a. Solar Radiation sensor specifications.
Output: 4-20mA
Range: 0-3000 Wm
Accuracy: 1% of full scale
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds m inimum
Operating Temperature: -40°C to +55°C
Size of Probe: 3" diameter x 1 1/2" high
Weight: 1/4 lb.
b. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.
Global Water
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2
c. Ensur e that the sensor is placed on a level surface, us e the alignment
bolts to adjust the sensor until it is lev el. Remove the red cap to begin
taking readings.
d. The solar radiation sensor or pyranomet er is an instr ument for
measuring solar radiation received f r om a whole hemisphere. It is
suitable for measuring global sun plus sky radiation. Solar radiation
varies significantly among regions. S eas on and time of day are major
considerations, but surroundin g terrain elevation, man-made
obstructions, and surrounding trees can als o c aus e lar ge v ar iations in
locations with a small area. Often, the required measurement is,
energy flux density of both direct beam and diffuse sky radiation
passing through a horizontal plane of known unit area (i.e., global sun
plus sky radiation).
e. Calibration should be confirmed annually.
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VI. Wind Speed Sensor
a. Wind Speed sensor specifications.
Output: 4-20mA
Range: 0-110 MPH
Accuracy: .2 MP H ov er the r ange 11 to 55 MP H
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temp: -40° to +55°C
Size of Probe: 7” diameter x 8 ½” long
Weight: 1 lb.
b. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.
Global Water
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c. The s ens or c om es w ith a stainless steel elbow that can be mounted on
a 1” diameter tube. For best results ens ur e that the s ens or is mounted
parallel to the ground surface.
d. The wind speed sensor or anemometer produces a s ine wav e v oltage
signal with a frequency that changes linearly with the wind speed. The
frequency is transformed into a 4-20 mA s ens or signal out put.
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VII. Wind Direction Sensor
a. Wind Direction sensor specifications.
Output: 4-19 mA
Range: 0 to 360° (352° electrical, 8° open)
Accuracy: 1% of full scale
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 3 seconds minimum
Operating Temp: -40° to +55°C
Size: 8 ½” diameter x 10 ½” long
Weight: 1 lb.
b. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.
Global Water
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c. The r idge on the fixed portion of the sensor represents t he 0° direction
of the sensor. The sensor comes with a stainless s teel elbow that can
be mounted on a 1” diameter tube. For best results ens ur e that the
sensor is mounted parallel to the ground sur face.
d. A wind direction sensor produces a ratiom etric voltage signal. That
voltage signal is transformed into a 4-19 m A sensor output signal.
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VIII. Humidity Sensor
a. Humidity sensor specifications.
Output: 4-19mA
Range: 0-100% RH
Accuracy: + 2% RH
Operating Voltage: 10-36VDC
Current Draw: 3 mA plus sensor
Warm Up Time: 3 seconds minimum
Operating Temp: -40° to +55°C
Size of Probe: 1 ½” diameter x 7” long
Weight: ½ lb.
b. The humidity sensor is a three-wire sensor. Three wire sensors use
the red wire for positive voltage, the w hite wire for the output signal,
and the black wire for ground. Warning: Alw ays con nect the
sensor with the power turned off.
Global Water
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c. Do not ins tall the humidity sensor in direct sunlight.
d. A humidity sensor utilizes a thin polymer that varies in dielectric
constant directly proportional to changes in the amount of water vapor
at the sensor element. The element provides a linear v oltage output
that is converted into a 4-19 mA sensor output signal.
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IX. Temperature Se nsor
a. Temperature sensor specifications.
Output: 4-19mA
Range: -50° C to + 50° C
Accuracy: ±0.2° F or ±0.1° C
Operating Voltage: 10-36VDC
Current Draw: Same as sensor output
Warm Up Time: 5 seconds minimum
Operating Temperature: -50°C to +100°C
Size of Probe: ¾" diameter x 4 ½" long
Weight: ½ lb.
b. The sensor is a two-wire sensor using the r ed wire f or power and the
black wire for the output signal. Warni ng : Always conn ect th e
sensor with the power turned off.
Global Water
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c. Do not ins tall the temperature sensor in direct sunlight.
d. To check the temperature sensor calibration y ou wil l need:
1 thermometer
3 containers of water
1 power supply
1 current meter
Connecting wires as necessary
Connect the sensor to the power supply and current meter in
the following way. Attach the black wir e to the positive input of the
current meter. Connect the ground ter minal of the power supply to the
ground of the current meter. Attac h the red w ire to the positive
terminal of the power supply. Warning: Always connect the sensor
with the power turned off.
See Appendix A for the temperature calibration worksheet.
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X. Solar Shield
a. Solar Shield specifications.
Size: 4” diameter x 8 ½” long
Weight: 1 lb.
b. The solar shield is used to protect sensors , t y pically humidity and
temperature, from direct sunlight. Insert a sensor into one of the two
holes located on the underside of the s hield. The shield provides a
friction lock so the sensors will not acc identally fall out. The sensors
can be removed by firmly twisting and pulling them out of the solar
shield.
c. The s hield c om es w ith a stainless steel elbow that can be mounted on
a 1” diameter tube. For best results ens ur e that the s hield is m ounted
vertically.
Global Water
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XI. Maintenance
a. Global Water recommends confirm ing the calibration annually.
b. The sensors should be cleaned periodical ly . Sensors can be cleaned
using a damp cotton cloth. NOTE: DO NOT submerge sensors . The
sensors are water resistant, not water proof.
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XII. Trouble Shooting
Issue: Sens or reading incorrectly
a. Verify power source is supplying correct v oltage.
b. Clean the sensor.
c. Confir m the sensor’s calibration.
Other issues
d. Call Global Water for tech support: 800-876-1172 or 979-690-5560
(many problems can be solved over the phone). Fax: 979-690-0440 or
Email:
globalw@globalw.com.
When calling for tech support, please have the following information
ready;
1. Model #.
2. Unit serial number.
3. P.O.# the equipment was purchased on.
4. Our sales number or the invoice number.
5. Repair instructions and/or specific problems relating to the
product.
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Be prepared to describe the problem you are experiencing including
specific details of the application, installation, and any additional
pertinent information.
e. In the event that the equipment needs to be returned t o the factory for
any reason, please call to obtain an RMA# (Return M aterial
Authorization). Do not return items without an RMA# displayed on the
outside of the package.
Clean and decontaminate the sens or if neces s ar y .
Include a written statement describing the problems.
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Send the package with shipping prepaid to our factory address. Insure
your shipment, Global Water’s warr anty does not cover damage
incurred during transit.
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XIII. Warranty
a. Global Water Instrumentation, Inc. warrants that its products are free
b. The warranty begins on the date of your invoice.
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from defects in material and workmanship under norm al us e and
service for a period of one year from date of shipment from factory.
Global Water’s obligations under this w ar r anty are limited to, at Global
Water’s option: (I) replacing or (II) repairing; any products determined
to be defective. In no case shall Global Water ’s liability exceed the
products original purchase price. This w ar r anty does not apply to any
equipment that has been repaired or altered, ex c ept by Global Water
Instrumentation, Inc., or which has been s ubjec t to misuse, negligence
or accident. It is expressly agreed that this warranty will be in lieu of
all warranties of fitness and in lieu of the warr anty of merchantability.
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Global Water
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XIV. Appendix A: Temperature Calibration check
Step 1) Fill a container of water with enough ice that it will not melt
quickly.
Step 2) Place the temper ature sensor and thermometer into the
container. Turn on the power supply and the current m eter.
Let the sensor stabilize for 30 minutes before taking any
measurements.
Step 3) Record the ice bath temperature, I
output current of the sensor, I
C
Step 4) Fill a container wit h enough w ar m water that it will not cool
down quickly.
Step 5) Place the temper ature sensor and thermometer into the
container. Turn on the power supply and the current m eter.
Let the sensor stabilize for 30 minutes before taking any
measurements.
Step 6) Record the warm water temperature, W
record the output current of the sensor, W
Step 7) Subtract I
Step 8) Subtract IT from W
Step 9) Calculate B. W
from W
C
- IC = _______ = C.
C, WC
- IT = _______ = T.
T, WT
– (C/T)(WT)= _______ = B.
C
Step 10) Find the low current value for the sensor. –(C/T)(50)+B= _____
= L
. This current is the output current the sensor would
C
produce if the temperature were -50°C.
Step 11) Find the high current value for the sensor. (C/T)(50)+B= _____
= H
. This current is the output current the sensor would
C
produce if the temperature were 50°C.
Step 12) Use these new cur r ent values to recalibrate the system that is
monitoring the sensor output.
= _______, and record the
T
= _______.
= _______, and
T
= _______.
C
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XV. Appendix B: 2 Wire Sensor Measurement Diagram
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XVI. Appendix C: 3 Wire Sensor Measurement Diagram
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