Question: We have had a problem with inclinometers shearing off. Does GeoFlex allow for more movement before becoming unusable?

Answer:  The GeoFlex does not allow for more movement, as both systems will perform until the signal cable  is pulled apart or cut. However, the shorter gauge lengths of the GeoFlex system do increase the reliability of the data once shearing begins. With the typical longer gauge of the IPIs, the shearing is more likely to bend the gauge rod making the displacement results questionable.

Question: Is the presentation of data different for GeoFlex versus IPIs? Can they all go to the same logger?

Answer:  Presentation of the data will be exactly the same (with the exception of the higher density of readings for GeoFlex – 2 feet vs 5 or 10 feet). Both systems are plotted as displacement vs. depth.

Both GeoFlex and IPIs can be installed on the same Campbell data logger. The GeoFlex uses an RS485 bus and the IPIs use an analog (RS232) bus.

Multiple GeoFlex strings can be connected to the same Campbell data logger. The number of strings depends on the logger you are using. The CR300 can handle one string, the CR800 three strings, and the CR1000 up to five strings. Please note that an MD-485 module will be required for each string. The CR6 and CR1000X can each handle two strings but do not require the MD-485 module as they have native RS-485 communication.

Question: IPIs can have different length gauge tubes. Why should I use GeoFlex instead of a short IPI?

Answer:  The IPI sensors have the flexibility of having variable length gauge tubes. They are most typically installed with 5 or 10 feet gauge tubes, but any length can be used down to about 1.5 feet. The GeoFlex system has a 2 feet gauge length at a cost of about the same as 10 feet gauge tubes for the IPIs, thus you achieve a higher density of readings over the same distance for the same cost.

Question: Are there any benefits to installing in 2.75” inclinometer casing over 1.5” PVC for GeoFlex?

Answer: The 2.75” inclinometer casing will be able to be read longer than the 1.5” PVC due to its larger diameter – the same way that 3.34” casing will be able to be read longer than the 2.75” casing. The larger diameter means that it will allow for more shear before it closes off completely.

The second advantage of casing over PVC is the ability to run traversing probes and spiral probes in the casing prior to installation of your permanent system. This is especially helpful in determining if you have an acceptable installation (angle from vertical, spiral, twist, etc.) prior to installing your permanent system. It is also helpful to be able to check the inclinometer in case there is ever a question about the results from your permanent system. While this is not often required, if it is needed the permanent system can be removed and a traversing probe run down the hole to validate the data. The traversing probe is not compatible with the PVC due to the lack of grooves.

Question: Can the GeoFlex or IPIs be removed so that a traversing inclinometer probe can be run down the inclinometer and then the GeoFlex or IPIs placed again in casing? If so, how difficult is this?

Answer:  Both the IPIs and the GeoFlex systems can be removed and replaced. Please note that a new baseline will need to be set once the system has been reinstalled. Due to the lighter weight of the system, the GeoFlex is generally considered easier to remove and replace.

Question: Can the GeoFlex be removed at the end of a project and used on a different project? For example, one with a different number and length of inclinometers.

Answer: Yes. The standard GeoFlex segment consists of five 2 feet nodes (10 feet total) that are connected electrically via a waterproof Seacon connector and mechanically via a pinned universal joint. Once the project is complete the system can be removed and broken down into its 10 feet segments (provided that the shear isn’t so great that they can’t be removed from the casing). Those segments can be used on another project and because each node is addressable, it doesn’t matter in what order the segments are installed on the next project.

The Campbell Scientific CR300, CR800 and CR1000 all require a module in order to read the RS485 signal. The CR6 and CR1000X can read the GeoFlex natively, but may require a module for additional strings. It should be noted that some of these layouts may preclude the reading of other sensor types and you should contact your DGSI representative if you have a more complicated layout.

Please click on the chart below to see how many strings can be installed on each logger model: