Diver Datalogger Frequently Asked Questions
How do I connect a Diver to my computer?
The way in which a Diver is connected to a computer depends on the way in which the Diver is deployed in the monitoring well.
- A Diver suspended from a steel cable must first be pulled up to the surface before it can be read. First, the cap of the Diver must be removed (turn counter-clockwise), before it is placed in the USB Reading Unit, see the picture below.
Is it possible to use the TD-Diver in seawater?
The TD-Diver and Micro-Diver are made of stainless steel 316L, which is not suitable for use in seawater. The Cera-Diver and CTD-Divers are made of zirconia, a ceramic material. This material does not corrode in seawater and these Divers can therefore be used in seawater. Van Essen Instruments explicitly selected a ‘non-metal’ for the Diver types required for use under more aggressive environments, such as seawater. Any metal will eventually corrode in an aggressive environment. The zirconia housing is extremely resistant to corrosion. The ceramic (Alumina) pressure sensors exhibits the same properties. The Viton o-rings have been selected for their favourable properties in aggresive environments.
Is a Diver limited to being used at sea level?
No, Divers can be used from 300 m below sea level to 5,000 m above sea level.
Does the Diver measure absolute pressure or referenced to atmospheric pressure?
All Divers measure absolute pressure. The Diver can be used from 500 meters below sealevel to 5,000 meters above sealevel.
What happens if the memory of a Diver is full?
This depends on which sample method is programmed in the Diver. If the sample method is set to "Continuous memory" then the Diver will continue to record by overwriting the oldest data point. If the sample method is set to "Fixed length memory" then the Diver will stop logging when the memory is full.
How do I install a Diver?
Most Divers are installed underwater in a monitoring well. The depth at which you can suspend a Diver depends on the instrument’s measurement range. Determine the lowest possible water level measured from the top of the casing (or another reference point) prior to the installation. If the Diver is at least suspended at this depth, it is then certain that the Diver always measures the water level.
The Diver can be suspended from a DXT-Cable or from a stainless steel suspension cable. Attach the Diver to the monitoring well cover and the suspension eye with two cable clips.
A CTD-Diver should preferably be installed in the well screen. The water in the screen will most likely have an electrical conductivity that is very close to that of the water in the aquifer. Therefore, if the CTD-Diver is installed in the screen the conductivity measurements will represent the electrical conductivity of the water in the aquifer.
Do I need a Baro-Diver?
Yes, you need a Baro-Diver to convert the readings of the Diver in to water levels.
The Diver measures absolute pressure. This means that it measures the pressure of the water that is above the Diver plus the barometric pressure. As a rule of thumb, at sea level the barometric pressure equals 10 meter (33 feet) of water pressure and fluctuates over time with about 1 meter (3 feet). Therefore, if you do not compensate for barometric pressure your water levels will be 10 meters higher and vary with about 1 meter.
The barometric compensation, subtracting the barometric pressure from the Diver pressure and referencing it to for example the top of casing, can be done through the Diver-Office software. Diver-Office comes with some example data that can be used as an exercise for barometric compensation. Click here to download a pdf file of the exercise.
Do I need a Baro-Diver for each monitoring well?
No, but at least one Baro-Diver to monitor barometric pressure must be included in each network. For example, one Baro-Diver can be used for a a network of 20 monitoring wells. We recommend installing one backup Baro-Diver for larger networks.
What is the radius from the Divers within which the Baro-Diver should be placed to ensure proper compensation for atmospheric pressure?
As a rule of thumb on open terrain, at approximately the same elevation, one Baro-Diver suffices for a radius of 15 km. More Baro-Divers may be required depending on the environment of the network, for example elevation changes, rivers, lakes, mountains. All these factors may affect barometric pressure differences per location.
How do I clean the Diver?
If a Diver is very dirty, it can be cleaned with a white vinegar solution. A diluted phosphoric acid solution may also be used for the Cera-Diver and CTD-Diver types.
- Place the Diver in the cleaning solution for some time.
- Thoroughly rinse the Diver with clean water after cleaning, especially near the flow through openings.
- If necessary, use a soft cloth to remove any deposits. Never use any hard brushes, abrasives or sharp objects to clean your Diver.
Must the Diver be calibrated?
No, this is not necessary. Van Essen Instruments calibrates the Divers before they are shipped. A factory calibration certificate can be supplied upon request.
The Divers can only be calibrated by Van Essen Instruments.
What is the Diver’s battery’s lifespan?
The battery’s lifespan is dependent on the measurement frequency, number of data downloads, number of times of programming. The capacity is based on:
- 10.5 million measurements;
- 1000 downloading a full memory;
- 2000 times programming
Given past experience, a maximum lifespan of 10 years is considered standard under ‘typical’ use. Typical use means that, among other things, Divers are not exposed to extreme temperatures over extended periods of time, the measurement sampling interval is not set at 1 second, a download is not requested by modem every hour, etc.
- 1 measurement per hour over a period of 10 years produces 87,600 measurements.
- 1 measurement every 15 minutes over a period of 10 years produces 350,400 measurements.
The lifespan of the battery is also affected by temperature. Extremely, high or low temperatures will reduce the lifespan of the battery.
Can I use a Diver for surface water applications?
Although the Divers are specifically designed for groundwater applications in mind, they can also be used in surface water applications. Two specific issues related to surface water are:
- rapid temperature fluctuations; the small size of the Diver makes it respond quickly to temperature changes.
- waves; the averaging sampling method in the Micro, Cera and CTD-Diver allows for reducing the effect of waves on the level measurements.
How is the specific conductivity in the CTD-Diver measured?
The specific conductivity Cs is calculated from the 'true' conductivity by using the following equation:
Cm = Conductivity at the temperature Tm
Cs = Conductivity at 25°C
Tm = Sample temperature in degrees Celsius
In the CTD-Diver the temperature coefficient is 1.91 %/°C and the reference temperature is 25 °C
Could the size of the well influence of the CTD-Diver if there is not much annular space?
The CTD-Diver measures the conducitivity inside a cavity. The conductivity sensor is designed such that only the conductivity of the solution inside this cavity is measured. Therefore, the well casing should not affect the measurements.
Does the Diver-Mate download the data the automatically once it is connected to the Diver Data Cable?
Yes, the Diver-Mate starts to upload data from the Diver automatically when the Diver-Mate is connected to the Diver Data Cable. Lights on the Diver-Mate indicate that download is in progress and when downloading the data has finished.
Can I configure a Diver using the Diver-Mate?
No, you cannot program or start/stop a Diver using a Diver-Mate. The Diver-Mate is designed to only download data from a Diver.
How much Diver data can I download with the Diver-Mate?
The Diver-Mate can hold more than 10,000 full Diver memories. You can download data from many Divers on a fully charged battery. A low battery indicator on the Diver-Mate will tell you it is time to recharge the battery.
How do I retrieve data from the Diver-Mate?
First you have to connect the Diver-Mate through the supplied USB cable to your computer. Then there are two options.
- You can use Windows File Explorer and copy the data from the Diver-Mate to your computer. This is identical to copying data from a USB Flash Drive.
- In Diver-Office go to Import > Diver-Mate/Diver-Pocket and the connected Diver-Mate will automatically be recognized. Click on the Receive button to import the data into Diver-Office. Alternatively, you can choose to remove the imported data from the Diver-Mate so you start with a clean Diver-Mate the next time you go in to the field.
Is there a warranty on my groundwater monitoring equipment?
Yes, there is a 1 year warranty on all groundwater monitoring equipment, including dataloggers, accessories and Diver-NETZ.