Global Water
800-876-1172 • globalw.com
00-997
10/25/06
Global Water
Instrumentation, Inc.
11390 Amalgam Way
Gold River, CA 95670
T: 800-876-1172
Int’l: (916) 638-3429, F: (916) 638-3270
Water Level Sensor: WL400
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Global Water
800-876-1172 • globalw.com
Congratulations on your purchase of the Global Water WL400 Water
Level Sensor. This instrument has been quality tested and approved for
providing accurate and reliable measurements. We are confident that you
will find the sensor to be a valuable asset for your application. Should you
require assistance, our technical staff will be happy to help.
Table of Contents
I. Checklist • • • • • • • Page 3
II. Inspection
III. General Sensor Installation • • • • 4
IV. WL400 Specifications
V. Maintenance
VI. Troubleshooting
VII. Warranty
• • • • • • • 11
VIII. Appendix A: Calibration Procedures
IX. Appendix B: 2 Wire Sensor Measurement Diagram
* Copyright © Global Water Instr umentation, Inc. 2006
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I. Sensor Checklist
a. Water Level Sensor
b. Water Level Sensor Manual
II. Inspection
a. The water Level sensor was carefully inspected and certified by Global
Water’s Quality Assurance Team before shipping. If any damage has
occurred during shipping, please notify Global Water Instrumentation,
Inc. and file a claim with the carrier involved.
Use the checklist to ensure that everything needed to operate the
water Level sensor was received.
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III. Sensor Installation
General
a. Water Level sensors have many applications and therefore many
installation options. All the sensors are fully submersible and may be
suspended by their waterproof cables in the water to be monitored.
b. Do not install the water Level sensor in applications that contain
solvents. Over time, many solvents can deteriorate the cable and the
sensing element.
c. Install the water Level sensor so that it is easily accessible for
calibration purposes. Take care not to kink the cable. This will close
the vent tube that the sensor uses to compensate for barometric
changes. Also be aware that the sensor may need to removed and
reinstalled in the future, so plan ahead!
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d. The sensor will not function correctly if mud, silt, leaves, or other
debris buries it. Install the sensor in a way that will avoid these
conditions.
e. All Global Water water level sensors produce a 4-20 mA output signal.
4-20 mA is an industrial standard signal for process control monitoring.
Most PLCs (Programmable Logic Controller), RTUs (Remote
Telemetry Unit), and data acquisition systems accept this signal
directly.
f. The power wire (red wire) must be connected to positive supply
terminal of the data logger or of the battery. The 4-20mA signal wire
(black wire) is connected to the data logger’s input terminal. If the
sensor is equipped with the optional temperature output circuit,
connect the output wire (white wire) to a second input terminal on the
logger in the same way as the level output.
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g. If the system only accepts voltage signals, the sensor output must be
converted to a voltage signal by reading the voltage across a precision
resistor in series with the signal wire. 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 5.00volts DC. If the 4-20 mA signal is dropped
across a 125 ohm resistor, the output will be halved to 0.5 to 2.50
VDC. The resistor is placed between this input and the ground
terminal of the data logger’s battery. The optional temperature output
produces a 0-10mA output current, generating either 0-2.50 volts or 0-
1.25 volts depending on the resistor selected.
h. The sensors may be manually pulsed on or turned on by the logging
system prior to taking a reading. Use a warm up time appropriate to
the water Level sensor being used to assure that the sensor is fully on.
The sensors can run continuously for real time applications. Each
sensor draws between 4 and 20mA depending on whether the sensor
is reading at the minimum or maximum of its range. The optional
temperature output will draw additional current up to the maximum
10mA.
Groundwater
i. The sensor may be suspended in a 2” monitoring well near the well
screen.
Surface Water
j. The sensor may be submerged at the monitoring point and hung from
its cable. It is recommended to protect the sensor inside a 4” PVC
drainpipe that will act as a protective stilling well. Put a cap on the
bottom end of the pipe to allow easy water flow past the sensors.
Drop the sensor until it touches the bottom of the stilling well and then
pull it up slightly and secure the cable.
Sewer Flow Option
k. The WL400 Sewer Pipe Flow Option includes a level sensor built into
a protective “mouse” housing and attached to a 12” stainless steel
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strap. The sensor/straps can be installed at the invert of a sewer or in
a pipe, the cable can be attached to a sewer’s stair rungs and run to
the data monitoring device.
l. When installed in a pipe that is under 12” diameter, the steel straps
spring into the pipe, holding the sensor in place. Additional fasteners
are usually not required for this type of installation.
m. For a sewer pipe over 12” diameter, the sensor’s steel straps must be
mounted into the pipe. The straps can be secured with molly or
concrete bolts, or with marine-grade epoxy.
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IV. WL400 Specifications
Sensing element:
Sensor Element: Silicone Diaphragm, Wet/Wet Transducer
Range: 0-3', 0-15', 0-30', 0-60', 0-120', 0-250'
Optional Temp: 32°-122°F (0°-50°C)
Linearity and Hysteresis: ±0.1% FS
Accuracy: Level: ±0.1% FS at constant temperature
Temp: Smaller of 0.5°F or ±1% of reading
Overpressure: 2 x full scale range
Resolution: Infinite (Analog)
Outputs: 4-20mA ±1mA at full scale
Optional Temperature: 0-10mA ±1mA FS
Supply Voltage: 10-36VDC
Current Draw: Sum of sensor outputs.
Warm Up Time: 10mS Min, 3 sec. recommended
Operating Temperature: 0° (Not Frozen) to +185°F
Compensated Range: 32° to 70°F submerged, automatic
Housing:
Material: WL400: 304L Stainless Steel
WL400-S: 316 SS
Size: WL400: 7.5” long x 0.82" diameter
WL400-S: 9” long x 1.0” diameter
Weight: WL400: 110g (4 oz)
WL400-S: 250g (9oz)
Cable:
Conductors: 4 each 22 AWG
Jacket Material: 87A shore hardness Polyurethane
Optional jacket: Fluorinated Ethylene Propylene (FEP)
Cable O.D.: 7.8mm (0.307”)
Vent tube: HD Polyethylene
Shield: Aluminum Mylar
Temperature range: -30 to 85°C (-22 to 185°F)
Weight: ~65g/m (0.7 oz/ft)
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±0.2% over 32° to 70°F range
barometric compensation
Teflon
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a. The sensor is a two-wire sensor using the red wire for power and the
black wire for the output signal. Warning: Always connect the
sensor with the power turned off.
b. The water level sensor may be stored without any special provisions.
Place the sensor inside a bag to keep the sensor clean and store on a
shelf or hang it on a wall.
c. To check the water level sensor calibration the following supplies are
needed:
1 column of water (the closer the depth is to the maximum range of the
sensor the better the calibration will be)
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 wire to the positive input of the
current meter. Connect the ground terminal of the power supply to the
ground of the current meter. Attach the red wire to the positive
terminal of the power supply. See Appendix B. Warning: Always
connect the sensor with the power turned off.
See Appendix A for the water level calibration worksheet.
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V. Maintenance
a. Global Water recommends verifying the sensor’s calibration with a
sounder or other measuring device once every 6 months.
b. The screen on the end of the sensor must be periodically checked for
clogging from mud, sludge, and other debris. Wash the screen with
clean water and/or scrub it gently with a toothbrush. Do not insert
objects through the screen, as this may cause damage to the sensor.
VI. Trouble Shooting
Issue: Sensor reading incorrectly
a. Verify power source is supplying the correct voltage.
b. Verify that the vent tube has not been kinked or sealed. The sensor
uses this tube to compensate for barometric pressure changes.
c. Clean the sensor following the maintenance instructions.
d. Verify the sensor’s calibration.
Issue: Water in the vent tube
a. If water gets into the vent tube of the cable place it next to a heater for
24 hours to dry the inside of the cable.
Other issues
a. Call Global Water for tech support: 800-876-1172 or 916-638-3429
(many problems can be solved over the phone). Fax: 916-638-3270 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. Global Water’s sales number or the invoice number.
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.
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5. Repair instructions and/or specific problems relating to the
product.
Be prepared to describe the problem being experienced including
specific details of the application, installation, and any additional
pertinent information.
b. In the event that the equipment needs to be returned to the factory for
any reason, please call to obtain a RMA # (Return Material
Authorization). Do not return items without a RMA # displayed on the
outside of the package.
Clean and decontaminate the WL400 if necessary.
Include a written statement describing the problems.
Send the package with shipping prepaid to our factory address. Insure
the shipment, Global Water’s warranty does not cover damage
incurred during transit.
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X. Warranty
a. Global Water Instrumentation, Inc. warrants that its products are
b. The warranty begins on the date of the product’s invoice.
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free from defects in material and workmanship under normal use
and service for a period of one year from date of shipment from
factory. Global Water’s obligations under this warranty 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 warranty does not apply to any equipment that has been
repaired or altered, except by Global Water Instrumentation, Inc.,
or which has been subject 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 warranty of
merchantability.
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Global Water
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XI. Appendix A: Calibration Procedures
Step 1) Turn on the power supply and the current meter.
Step 2) Record the output current of the sensor, I
Step 3) Place the water level sensor into the column of water.
Step 4) Record the depth of the sensor (the distance from the tip of the
sensor to the top of the column of water, W = _______, and
record the output current of the sensor, I
Step 5) Subtract I
from I
L
- IL = _______ = C.
H, IH
Step 6) Find the maximum current output for the sensor. (C/W)(Max
Range of sensor)+ I
= _____ = Output current.
L
Step 7) Use these new current values to recalibrate the system that is
monitoring the sensor output.
= _______.
L
= _______.
H
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XII. Appendix B: 2 Wire Sensor Measurement Diagram
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