All Divers FAQ

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.

• A Diver suspended on a DXT-Cable can be left hanging in the well. Connect the top of the DXT-Cable to the computer using the Smart Interface Cable.

The TD-Diver and Micro-Diver are made of stainless steel 316L, which is not suitable for use in sea water. The Cera-Diver and CTD-Divers are made of zirconia, a ceramic material. This material does not corrode in sea water and these Divers can therefore be used in sea water. Van Essen Instruments explicitly selected a ‘non-metal’ for the Diver types required for use under more aggressive environments, such as sea water. 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 aggressive environments.

No, Divers can be used from 500 m below sea level to 5,000 m above sea level.

All Divers measure absolute pressure. The Diver can be used from 500 meters below sea level to 5,000 meters above sea level.

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.

There are various option to install a Diver. Three common options are

• 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.

You will need barometric pressure data to convert the readings of the Diver in to water levels. The barometric pressure data can be measured by a Baro-Diver. Alternatively, online barometric data from a nearby weather station can be used.

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.

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.

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.

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.

1. Place the Diver in the cleaning solution for some time.
2. Thoroughly rinse the Diver with clean water after cleaning, especially near the flow through openings.
3. If necessary, use a soft cloth to remove any deposits. Never use any hard brushes, abrasives or sharp objects to clean your Diver.

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.

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 times downloading a full memory and
• 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 to 1 second, a data download is not requested every hour, etc.

Examples:

• 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.

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.

Yes, there is a 1 year warranty on all groundwater monitoring equipment, including dataloggers, and accessories.