Transporting monitoring instruments

You must ensure that the sonde and sensors are not damaged or the calibration impacted during transport to the field site.

Here are a few tips:

• It's better not to transport sonde with the calibration cup. Removing the cup in the field exposes the sensors and can be costly if an accident happens.
• Instead, install the sonde guard and wrap the sonde in a wet white towel to keep the sensors in water-saturated air
  
  
  
  -OR-
• Transport using a white cooler that has been vented. Use 1-inch foam in the bottom for shock and vibration protection.
• The cooler will maintain a saturated-air environment for the pre-deployment DO check.

If you are transporting sondes for "unattended" deployment, you should check the instrument's data while it is in transit to the site. Verify that the instrument is still running and check the DO data that was recorded while in the wet towel or cooler.

If "sampling," you can power up the instrument while it is in the wet towel or cooler and check the DO. You should do this at the beginning of each site measurement and at the end to ensure good DO data. This is especially important with Clarke-type or polarographic DO sensors.

Calculating DO Readings

For both optical and polarographic DO sensors, the DO% readings can be calculated by dividing the local barometric pressure (mm hg) by 7.6.

Example: 760 / 7.6 = 100%

Each monitoring site is unique and care should be taken to identify possible problems upfront (biofouling, aquatic vegetation, storms, vandalism, etc.) and address them during the platform design.

These steps will help you avoid common problems in natural environments and make the most of your monitoring platform:

• Install sonde so that it is always submerged, even at low tide, and at a fixed distance from the bottom (or the surface).
• Sondes should be installed inside a perforated pipe or steel cage to protect it from hazards such as floating logs.

Perforated pipe

This mounting pipe has been drilled with 0.75" holes on 2.0" centers. A 0.5"bolt is installed through the bottom as a stop for the sonde.

Steel mooring cage

• If deploying in an environment where biofouling is expected, then the pipe should be protected from fouling. Pipes that are not protected can have the flow-through holes sealed with growth in a short period of time.
• If considering a bottom-mounted deployment, be aware that sediment re-suspension from the bottom may adversely affect readings.
• To attach the PVC or ABS pipe to a piling or other structure, use stainless steel hose clamps and drive screws. You can check this with a magnet. You could also use copper clevis hangers mounted to a treated 2x4 board.
• To protect your equipment from potential vandalism, consider using a chain and padlock through the tube and a locking well cap.

You may also want to check out this comprehensive document for designing and setting up environmental monitoring stations:

Chesapeake Bay NERR Guidelines for Shallow Water Quality Monitoring: Continuous Monitoring Stations [PDF 5.9MB]

Chap 3: Selection and Assembly of Sensors Protection Device

Battery Voltage

It is important to monitor battery voltage preferably before and during a deployment. Sondes can operate 6-13.8 volts (depending on model). However, battery consumption is extremely dynamic based on sampling interval, optical wiper interval, number of parameters, etc. The monitoring sonde has a meter to estimate the useful battery life based on these dynamics.

If you are not attaching the sonde to an external power source, then checking this meter is critical.

When you are attaching to an external power source, then the battery voltage will qualify the reserve capacity and solar panel operation during a deployment.

If you need assistance with building and deploying your monitoring site, contact YSI's field services team.

info@amjenviro.com
877-392-9950 or 727-565-2201