Instrumentation Northwes AquiStar PT2X Manuel utilisateur
INSTRUMENTATION NORTHWEST,I NC.
AquiStar
PT2X
Smart Sensor
Pressure/Temperature
Sensor and Datalogger
Including PT2X-BV
Barometric/Vacuum Sensor
INSTRUCTION
MANUAL
®
Instrumentation
Northwest, Inc.
Protecting our water resources since 1982
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Table of Contents
Introduction ..................................................................................................................... 3
What is the PT2X? .................................................................................................... 3
Initial Inspection and Handling ................................................................................ 3
Do’s and Don’ts ....................................................................................................... 3
How Pressure Sensors Work ........................................................................................... 4
Installation ....................................................................................................................... 6
Installing the Sensor ................................................................................................. 6
Connecting External Power ....................................................................................... 7
Installing the Aqua4Plus Software ............................................................................ 7
Connecting the PT2X to a Computer ........................................................................ 8
Maintenance .................................................................................................................... 8
Changing Batteries ................................................................................................... 8
Desiccant Tubes ...................................................................................................... 10
Recalibration and Check-up ..................................................................................... 10
Miscellaneous ......................................................................................................... 10
Trouble Shooting ............................................................................................................ 11
Erratic Readings ....................................................................................................... 11
Oscillating Readings Over Time .............................................................................. 11
Zero Readings When Pressurized ........................................................................... 11
Grounding Issues .................................................................................................... 12
Appendix A: Technical Specifications ............................................................................ 13
General Specification ............................................................................................... 13
Wiring and Component Information ........................................................................ 13
Operating Specifications .......................................................................................... 15
Mechanical Specifications ....................................................................................... 15
Battery Life Calculation ........................................................................................... 16
Appendix B: Field Calibration (Pressure) ........................................................................ 17
Appendix C: Measuring Elevation or Depth-to-Water ................................................... 19
Measuring Depth-to-Water ..................................................................................... 19
Measuring Groundwater Elevation .......................................................................... 20
Appendix D: Using USB to Serial Cables ........................................................................ 21
Appendix E: PT2X-BV Barometric/Vacuum Sensor ......................................................... 22
What is the PT2X-BV? ............................................................................................. 22
Software ................................................................................................................... 22
Connecting the PT2X-BV to a Computer ................................................................. 23
Recalibration and Check-up ..................................................................................... 23
Changing Batteries .................................................................................................. 23
Operating and Mechanical Specifications ............................................................... 24
Reordering Information ................................................................................................... 25
Limited Warranty/Disclaimer-AquiStar® PT2X .............................................................. 26
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Information in this document is subject to change without notice and does not represent
a commitment on the part of the manufacturer. No part of this manual may be
reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording, for any purpose without the express written
permission of the manufacturer.
©1997 - 2004 Instrumentation Northwest, Inc.
Registered trademarks and trademarks belong to their respective owners.
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Introduction
What is the PT2X?
INW’s AquiStar®PT2X Smart Sensor is a submersible pressure/temperature sensor and
datalogger combined in one small diameter unit. This industry standard digital RS485
interface device records over 130,000 records of pressure, temperature and time data,
operates with low power, and features easy-to-use software with powerful features.
The PT2X is powered internally with two AA batteries or with an auxiliary power
supply for data intensive applications. The unit is programmed using a laptop or
desktop Windows®based computer via its RS485/RS232 connector and easy to use
Aqua4Plus software. Once programmed the unit will measure and collect data on a
variety of time intervals.
The AquiStar®PT2X can be used to replace analog sensors hooked to separate
dataloggers. The MODBUS®interface protocol can be used for RTU and PLC applica-
tions. (See factory for details. ) Units can be used to monitor groundwater, well, tank
and tidal levels, as well as for pump testing and flow monitoring.
Initial Inspection and Handling
Upon receipt of your smart sensor, inspect the shipping package for damage. If any
damage is apparent, note the signs of damage on the appropriate shipping form. After
opening the carton, look for concealed damage, such as a cut cable. If concealed
damage is found, immediately file a claim with the carrier.
Check the etched label on the sensor to be sure that the proper range and type were
provided. Also check the label attached to the cable at the connector end for the proper
cable length.
Do’s and Don’ts
Do handle the device with care.
Do store the device in a dry, inside area when not in use.
Do install a desiccant tube if you are doing long-term outdoor monitoring.
Don’t install the device so that the connector end is submerged.
Don’t support the device with the connector or with the connectors of an extension
cable. Use a strain relief device to take the tension off the connectors.
Don’t allow the device to free-fall down a well at high velocities as impact damage
can occur.
Don’t bang or drop the device on hard objects.
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How Pressure Sensors Work
The following paragraphs outline the basics of how pressure is measured using
submersible pressure sensors:
Liquids and gasses do not retain a fixed shape. Both have the ability to flow and are
often referred to as fluids. One fundamental law for a fluid is that the fluid exerts an
equal pressure in all directions at a given level. Further, this pressure increases with an
increasing depth of “submergence”. If the density of a fluid remains constant
(noncompressible...a generally good assumption for water at “normal” pressures and
temperatures), this pressure increases linearly with the depth of “submergence”.
We are all “submerged” in the atmosphere. As we increase our elevation, the pressure
exerted on our bodies decreases as there is less of this fluid above us. It should be
noted that atmospheric pressure at a given level does vary with changes in the weather.
One standard atmosphere (pressure at sea level at 20º C) is defined to be 14.7 PSI
(pounds per square inch).
There are several methods to reference a pressure measurement (see Figure 1). Abso-
lute pressure is measured with respect to an ideal vacuum (no pressure). Gauge
pressure is the most common way we express pressure in every day life and is the
pressure exerted over and above atmospheric pressure. With this in mind, gauge
pressure (Pg) can be expressed as the difference between the absolute pressure (Pa) and
atmospheric pressure (Patm):
Pg = Pa - Patm
Figure 1: Pressure Diagram
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To measure gauge pressure, atmospheric pressure is subjected to one side of the system
and the pressure to be measured is subjected to the other. The result is that the differen-
tial (gauge pressure) is measured. A tire pressure gauge is a common example of this
type of device.
Recall that as the level of submergence increases (in an incompressible fluid), the
pressure increases linearly. Also, recall that changes in weather cause the absolute
atmospheric pressure to change. In water, the absolute pressure Pa at some level of
depth (d) is given as follows (see Figure 2):
Pa = Patm + kd
where k is simply a constant (i.e.: 2.307 ft of water = 1 PSI)
Figure 2: Pressure Diagram, Detail "A"
INW’s standard gauge submersible pressure devices utilize a vent tube in the cable to
allow the device to reference atmospheric pressure. The resulting gauge pressure
measurement reflects only the depth of submergence. That is, the net pressure on the
diaphragm (Figure 2) is due entirely to the depth of submergence.
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Installation
Installing the Sensor
The PT2X measures pressure. The most common application is measuring liquid levels
in wells and tanks. In order to do this, the sensor must be installed below the water
level at a fixed depth. The installation depth depends on the range of the sensor. One
(1) PSI is equal to approximately 2.31 feet of water. If you have a 5 PSI sensor, the
range is 11.55 feet of water and the sensor should not be installed at a depth below
11.55 feet. If the sensor is installed below its maximum range, damage may result to
the sensor and the output reading will not be correct.
Monitoring Wells
Lower the sensor to the desired depth. Fasten the cable to the well head using tie wraps
or a weather proof strain-relief system. When securing a vented cable, make sure not to
pinch the cable too tightly or the vent tube inside the cable jacket may be sealed off.
Take a measurement to insure the sensor is not installed below its maximum range.
Important Note: If the sensor is to be left in the well for a long-term monitor-
ing application and the connector end is not in a dry, thermally-stable environ-
ment, a desiccant tube must be installed in line with the cable to prevent
condensation in the cable vent tube. Water in the vent tube will cause inaccu-
rate readings and, in time, will work its way into the sensor and damage it.
Instrumentation Northwest, Inc.
PS9105 0-30PSIG
MADEINRE DMOND, WA USA-PA TENT# 5,033,297
Figure 3: Installation
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Other Installations
The sensor can be installed in any position; however, when it leaves the factory it is
tested in the vertical position. Strapping the sensor body with tie wraps or tape will not
hurt it. INW can provide an optional 1/4" NPT input adapter which is interchangeable
with the standard end cone for those applications where it is necessary to directly attach
the sensor to a pipe, tank or other pipe port (see Figure 3). If the sensor is being
installed in a fluid environment other than water, be sure to check the compatibility of
the fluid with the wetted parts of the sensor. INW can provide a variety of seal materi-
als if you are planning to install the sensor in an environment other than water.
Connecting External Power
The PT2X comes with two AA internal batteries. This provides enough power for at
least one year of operation at the rate of four measurements per hour. (See Battery Life
Calculation section in Appendix A for further details.)
If auxiliary power is desired, you can use a 6 - 13 VDC supply that can provide 15 ma.
Connect to Vaux++ (white) and Ground (blue) or contact INW for auxiliary power
connectors.
Installing the Aqua4Plus Software
The PT2X comes with the Aqua4Plus host software that is installed on your PC or
laptop. This software is used to program the datalogger, to retrieve data from the logger,
to view collected data, and to export data to external files for use with spreadsheets or
databases.
Refer to the Aqua4Plus software manual for details on installing and using Aqua4Plus.
Software is also available for some handheld PDA’s. Contact your sales representative
for details.
Using the PT2X Without Aqua4Plus
For those who want to access the PT2X data via the Modbus protocol and their
own software, please refer to the application note “Converting Raw Data from PT2X and
Applying Calibration Values” - available at:
http://www.inwusa.com/pdfs/pt2x_converting_raw_data.pdf
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Maintenance
Changing Batteries
Because changing the batteries involves opening the water-tight seal, this must be
done in a clean, dry environment to avoid contamination or moisture damage to the
circuitry.
Battery Type
The PT2X uses two standard AA Alkaline batteries. A fresh set of batteries should last
up to one year when taking four samples per hour. For details in calculating battery life,
see Appendix A.
Connecting the PT2X to a Computer
In its cabled configuration, the Smart Sensor cable is terminated with a waterproof
connector. In its free-suspension configuration, the PT2X is terminated with a screw-
cap. Remove the screw-cap to access the waterproof connector. Connect the waterproof
connector to your PC or laptop serial port via the interface cable and an RS485/RS232
adapter, as shown below. For USB connections, see Appendix D.
Figure 4: Connecting the PT2X to a computer
PC or Laptop
Computer
RS485/RS232
Adapter
Interface
Cable
Waterproof
Connectors
Serial Port
PT2X
Screw-
PT2X
cap Free-Suspension
Configuration
PC or Laptop
Computer
RS485/RS232
Adapter
Interface
Cable
Waterproof
Connectors
Serial Port
PT2X
PT2X
Cable
Cabled
Configuration
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Replacing the Batteries
Open the housing by removing the top-cap, as outlined below. The top-cap is the
connector between the tube housing the PT2X and the cable. (See figure 7, page 14 for
illustration.)
1. Remove the two set screws at the top of the housing tube, using a 1/16” allen
wrench.
2. Very gently work the top cap loose. Note, two o-rings provide a water-tight seal
for the PT2X housing and often seal tightly. Inserting the blade of a flat screw-
driver between the top-cap and the housing and twisting gently can help to
release the o-rings’ seal. Then rock the top-cap back and forth, while applying
steady, but controlled, upward pressure.
Caution! Pulling forcefully on the top-cap can cause the O-rings to
release suddenly and the top-cap to disengage with enough force to
pull the insides out of the sensor or snap the connections inside.
Removing the circuit board or pushing on the surface of the pressure
element may void your warranty.
3. Remove the black service connector (Figure 5)
4. Tip housing over and gently slide batteries out.
5. Insert new batteries - positive terminals towards the top-cap.
6. Replace service connector. Note: this connector is keyed and can only be
connected in one direction.
7. Carefully wrap the cable around the slot in the connector board.
8. Replace top-cap.
9. Replace set screws and tighten with a 1/16” allen wrench.
Figure 5: Removing Service Connector
Service
Connector
Ce manuel convient aux modèles suivants
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