Our engineering team at Measurand spends a lot of time improving and revising our software and manuals and providing what we hope is outstanding support for our products. For SAAV, and for many other geotechnical instruments, installation details are key to success of monitoring programs.
The following is a short list of installation concerns that will greatly increase the success of incorporating SAAV into your monitoring program. These items frequently arise as causes when we hear from customers about issues with data, or that we see in some installation photos. All of the information in the list can be obtained in the SAAV manual.
For those planning to install SAAV, we hope this list will provide a good synopsis of some common installation and pre-installation planning faults that can be avoided. It should be used in conjunction with the information presented in the SAAV manual.
1. Settle the SAAV inside the casing before compressing and securing the SAAV inside the casing
During the installation process, the SAAV will undergo compression under its own weight. To ensure that the SAAV is properly settled into the casing, make a physical mark on the Extension Tube to mark the position of the SAAV inside the casing. Pump the SAAV up and down approximately 0.5 m to 1 m, using an action similar to churning butter. This will help to arrange the joints in a stable position. Repeat this process until little or no increase in settlement is observed using the mark made on the Extension Tube. Use the SAAV Installation Verification tool from the Diagnostics menu in SAARecorder to confirm that the SAAV is properly settled.
2. Secure the SAAV inside the casing
Use the Measurand SAAV Casing Cap or Compression Clamp to secure the SAAV to the casing. If left unsecured, the SAAV can rotate within its casing, which can produce data that looks like deformation, but is simply rotation. The erroneous-data problem increases with slant of the SAAV away from vertical. It is possible to correct most rotations using the anti-rotation algorithm in software, but it is better to minimize it mechanically first.
4. Be aware that SAAV can be damaged by lightning
When an SAAV has a long cable, energy from a nearby lightning strike can induce electromagnetic forces along the SAAV cable. Use a Measurand SAA Surge Protection Device (SAASPD) near the top of the SAAV with long cables to protect it from these surges. An SAA232 or SAA232-5 at the logger station provides some protection for the logger. Using an SAASPD will minimize the chances of destruction by nearby lightning strikes. For more information, see ShapeArray™ Lightening Protection.
5. Ensure SAAV is connected directly to the power source
When logging with Campbell Scientific data loggers via a Measurand SAA232 or SAA232-5 interface, we recommend that you power the SAAV directly from a 12 V power source, such as a battery, without going through the data logger. The current being drawn by the SAAV can overwhelm the logger's ability to provide power under some circumstances. This can lead to bad readings being recorded by the logger as the SAAV is not receiving appropriate power. We recommend connecting the red and black wires from the SAA232 or SAA232-5 directly to the power source instead of a logger's 12 V and G terminals.
6. Ensure that water cannot freeze within the casing
If there is water inside the casing after the SAAV has been installed, steps must be taken to ensure that the water does not freeze. Water freezing within the casing can cause pressures that greatly exceed the tolerances of the SAAV which can lead to damage to the instrument. Consult local guidelines for antifreeze before installation.