Smart Sensor FAQs
What are PSIA (absolute), PSIG (gauge), and PSIS (sealed gauge) pressure sensors and how do they differ?
PSIA (absolute) sensors measure the depth plus the atmospheric pressure. This atmospheric pressure must be subtracted from the absolute pressure to give the actual pressure due to depth. For information on using the Aqua4Plus Barometric Compensation utility to perform these calculations, refer to the Barometric Compensation Utility application note.
INW’s PSIG (gauge) sensors 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.
INW also offers a PSIS (sealed gauge) pressure sensor. This is an absolute sensor to which 14.7 PSI offset has been included to account for air pressure. Thus the measurements reflect only the pressure due to depth, when assuming a standard barometric pressure of 14.7 PSI.
What is the desiccant tube and what do I do with it?
The desiccant tube prevents moisture in the air from being sucked into the vent tube, which can cause erratic readings and sensor damage. Install the sensor so that the desiccant tube will not flood or lie in water.
The desiccant is a bright blue color when active and dry. As moisture is absorbed the color will begin to fade becoming light pink, indicating full saturation and time to replace. The life of the desiccant varies depending on the environment in which it is installed. The damper the environment or the higher the humidity, the more often the desiccant will need to be replaced. Inspect the desiccant every few weeks, until you know how it responds in your particular environment. Desiccant refill bottles can be purchased from INW.
I’m getting erratic readings from my sensor.
Erratic readings can be caused by a poor connection, damaged cable, moisture in the unit, or a damaged sensor. In most cases, erratic readings are due to moisture getting into the system. First check the connection. Look for moisture between contacts or a loose or broken wire. Next, check the cable for cracking or fraying. If the connections and cable appear okay, but the readings are still erratic, the sensor may be damaged. Contact INW for evaluation and repair.
Erratic and erroneous readings can also occur due to improper grounding. See the Grounding Issues application note.
Pressure readings are oscillating over time.
If, after time, your sensor is functioning normally but your data is showing a cyclic effect in the absence of water level changes, you are probably seeing barometric changes. The amount is usually 0.5 to 1.5 feet of water. This can be caused by actual water level changes in the aquifer in response to barometric pressure changes. This effect can occur in tight formations where the sensor will immediately pick up barometric changes but the aquifer will not. If you think you are having this type of problem you will have to record the barometric pressure, as well as the water level pressure and compensate the data.
This can also be caused by a plugged vent tube in the cable. If a desiccant tube is not installed in line with the cable, or if the desiccant is fully saturated, water may have condensed in your vent tube causing it to plug. If it appears that the vent tube is plugged, consult the factory.
My pressure readings are zero.
Continuous zero readings are usually caused by an open circuit, which may indicate a broken cable, a bad connection, or possibly a damaged sensor. Check the connector to see if a wire has become loose or if the cable has been cut. If damage is not readily apparent, contact INW for evaluation and repair.
Will Aqua4Plus work on Windows 7?
Yes, Aqua4Plus works on both the 32 bit and 64 bit versions of Windows 7.
How can I get the most current software for my AquiStar Smart Sensor?
The most current release of Aqua4Plus can be downloaded from our web site: HERE.
I can’t communicate with my AquiStar Smart Sensor.
Your sensor should be connected to your computer as shown below:
Be sure the RS232 end of the RS485/RS232 connector is the end connected to your computer. If this is backwards, communication will fail.
If you do not have a serial port on your computer, see application note Using USB-to-Serial Cables to Connect AquiStar® Smart Sensors.
Make sure all connections are secure.
Be sure you have selected the correct COM port on the main window in Aqua4Plus.
Be sure you have selected the highest and lowest sensor address that you want to talk to in the Communications dialog box on the Options menu.
I don’t have a serial port on my computer.
See the application note Using USB-to-Serial Cables to Connect AquiStar Smart Sensors.
My PT2X measures pressure in PSI. How can I change this to feet of water or other units?
In Aqua4Plus, click on the Options menu and then select Display Units. Use this to select the units in which to display our data. This will control how data is represented on the Real Time Monitor, the File Display Window, the Graph Window, and for exported data.
I want to use my PT2X to measure water elevation. How do I do this?
Refer to Appendix C in the PT2X Manual.
How do I change the batteries in my AquiStar Smart Sensor?
The following AquiStar Smart Sensors use two standard AA Alkaline batteries – PT2X, CT2X, and TempHion. To change batteries, the housing for the sensor must be opened. Because there is sensitive electronic circuitry inside the housing, battery changing must be done in a clean, dry environment to avoid contamination or moisture damage to the circuitry.
For details on changing batteries in these sensors, refer to the Changing Batteries in AquiStar Smart Sensors application note.
How long will the batteries last in my AquiStar Smart Sensor?
Battery life varies by sensor type, frequency of recording, frequency and length of communication for uploading, original freshness of batteries, temperature, and other factors.
Following are sample estimates for battery life in a PT2X
| Records per hour | Battery life in weeks |
| 1 | 60 |
| 10 | 46 |
| 120 | 12 |
For estimates on other sensors, please contact your INW sales representative.
Can I run my AquiStar Smart Sensor on auxiliary power?
AquiStar Smart Sensors come with two AA internal batteries. If auxiliary power is desired, you can use a 6 – 13 VDC supply that can provide 15 mA. Connect to Vaux++ (pin 1 – white) and Ground (pin 5 – blue) or contact INW for auxiliary power supplies.