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CTD

Groundwater data logger

FAQ

FAQ

How do I install my OTT CTD?
How do I connect an CTD to my computer?
How long does an OTT CTD battery last?
Can the OTT CTD be used in saltwater?
How do I clean my OTT CTD it it is very dirty?
Does the OTT CTD have to be calibrated?
When does the OTT CTD have to be calibrated?
How do I calibrate my OTT CTD?
How often should I calibrate my OTT CTD?
Can I order individual cable lengths?
What waterlevel measurement ranges are available?
What is the maximum depth of water that I can use the OTT CTD in?
Is it possible to order a manual portable reel?
Of what material is the communication cable made of and how solid is it?
How fast is the response time of the system for depth, temperature and conductivity measurements?
Where can I get software upgrades?
How long is the turn around time for repairs?
How can I contact OTT in case of problems?
How do I arrange a return for instrument service and/or calibration?
Can I set up more than one scheduled test on the OTT CTD?
How do I transfer data from the rugged PDA TDS Recon to my PC/Laptop?
How do I synchronize the clock on the OTT CTD with my PC/Laptop?
How do I determine the COM port number for my USB and Infrared interface?
What can I do when I'm unable to connect the OTT CTD to the user software?
Can drift of the values happen?
Is the OTT CTD only for groundwater applications?
Can I attach a telemetry device to OTT CTD unit?
What can I do when the data communication from PC/Laptop to the OTT CTD fails?
Is the OTT CTD applicable for very contaminated groundwater e.g. landfills where oil or other contaminants are present?
When should an OTT CTD be used?
What is conductivity?
What is the difference between conductivity and specific conductance?
How is salinity measured using this sensor?
How do I determine total dissolved solids (TDS)?
Can I do a specific conductance parameter setup?

How do I install my OTT CTD?

Most OTT CTDs are installed underwater in a monitoring well. The depth at which you can suspend an OTT CTD depends on the measuring range of the instrument. For installation, determine the lowest possible water level measured from the top of the well (or another reference point). If you then hang the OTT CTD at least at this depth, you will be certain that the OTT CTD can always measure the parameters. back...

How do I connect an OTT CTD to my computer?

The communication between the OTT CTD and a PC/Laptop can be established via infrared interface (IrDA) using an OTT IrDa-link USB cable with infrared reading head or an OTT Duolink Infrared reading head with RS232 connector (RS232 or USB - depends on the interfacing possibilities of the PC/Laptop.
Set up a communication link:

Connect the OTT IrDA-Link USB to a USB interface or the OTT DuoLink (RS232 connector) optical reading head to a RS232 COM Port of your PC/Laptop.

Place the optical reading head onto the OTT CTD infrared interface.

Start the CTD operating program and select the right communication path. back...

How long does an OTT CTD battery last?

The lifetime of a battery depends on the measuring intervals, readout and programming cycles.

Example for: 1h measurement interval / 50 m cable lengths / readout once per month

Lifetime 5 years (or longer) with lithium battery

Lifetime 1.5 years with alkaline battery
back...

Can the OTT CTD be used in seawater?

The OTT CTD housing is made of high quality stainless steel (904L). The pressure sensor is made out of corrosion free ceramic material. back...

How do I clean my OTT CTD if it is very dirty?

If your OTT CTD is very dirty (sediment, biofoulig film etc.), use descaler agent to thoroughly clean the instrument. Immerse the OTT CTD in the solution for a while to soften the gunk. After cleaning, always rinse the OTT CTD with clean water. If necessary, use a soft cloth to remove any scale. Never use hard brushes, abrasives or sharp objects to clean your OTT CTD. back...

Does the OTT CTD have to be calibrated?

OTT Hydromet calibrates its OTT CTDs before they are shipped (the OTT CTD is factory calibrated and ready for deployment).
A factory acceptance test certificate (FAT) comes automatically with every new CTD. After the factory calibration there is no need to calibrate the new OTT CTD again. The sonde is ready for deployment. Later it is recommended that the conductivity cell is calbirated regularly to ensure that measurement results remain reliable. back...

When does the OTT CTD have to be calibrated?

We recommend calibrating the OTT CTD at the beginning of a new measurement campaign. If you calibrate the OTT CTD after the measuring campaign as well, you will have a better understanding of any irregularities during the measuring campaign. back...

How do I calibrate my OTT CTD?

With the intuitive and user friendly operating software the user is guided through the calibration procedure step by step. back...

How often should I calibrate my OTT CTD?

For optimum performance we recommend that you calibrate your CTD annually. back...

Can I order individual cable lengths?

Individual cable lengths can be ordered for the OTT CTD. Max. cable length is 200 m. back...

What waterlevel measurement ranges are available?

The offered waterlevel measurement ranges are 0-4m / 0-10m / 0-20m / 0-40m / 0-100m back...

What is the maximum depth of water that I can use the OTT CTD in?

100m back...

Is it possible to order a manual portable reel?

At the moment there is no portable reel available, but it is planned to offer a solution for this. back...

Of what material is the communication cable made of and how solid is it?

Overview of used materials

Pressure probe: stainless steel 1.4539 (904 L) and POM

Conductivity sensor: ABS, Graphite (Electrodes) and stainless steell 1.459 (904 L), (NTC-housing)

Cable: PUR

Communication unit: stainless steel 1.4301 (304) and 1.4462 (UNS S31803) and PC/Laptop/ABS back...

How fast is the response time of the system for depth, temperature- and conductivity measurements?

Depth sensor: Reaction time 200 mS

Temperature sensor: Reaction time 200 mS

Conductivity sensor: 2 secondes to get a value - output value is an average value of several measurements.

However, the minimum measurement interval of the OTT CTD is fixed to 5 seconds. back...

Where can I get software updates?

On the OTT Hydromet website (www.ott.com) - Login in "myOTT". back...

How long is the turn around time for repairs?

10 days. back...

How can I contact OTT in case of problems?

Send an Email (hydroservice@ott.com) or Fax (Fax +49 831 5617 439) to the OTT HydroService, or give us a call: Tel +49 831 5617 430. For repairs and questions referring repair please use: Tel +49 831 5617 433, Fax + 49 831 5617 439 or Email repair@ott.com. back...

How do I arrange a return for instrument service and/or calibration?

If you would like to return equipment for service, please use the OTT Service Memorandum document, available at: http://www.ott.com/web/ott_de.nsf/if/pa_repservice_e.html. Please fill in the required fields and then submit the form together with the instrument. back...

Can I set up more than one scheduled test on the OTT CTD

You can store individual instrument configurations on the PC/Laptop. If a different or new configuration is needed, the stored configuration file can be opened with the OTT CTD configuration software and downloaded to the OTT CTD. back...

How do I transfer data from the Rugged PDA TDS Recon to my PC/Laptop?

Use Microsoft Active Sync Software to establish a connection between the PC/Laptop and the TDS handheld. back...

How do I synchronize the clock on the OTT CTD with my PC/Laptop?

By using the CTD configuration software - select "time sync with PC/Laptop". back...

How do I determine the COM port number for my USB and Infrared interface?

Auto detection by PC/Laptop. back...

What can I do when I'm unable to connect the OTT CTD to the user software?

Make sure that all physical connections are secure and properly installed. If necessary reset all devices. Then, make sure that the COM port number in the OTT CTD user software settings matches the COM port assigned to the drive on the PC/Laptop device manager. Connect the instrument to the software. If this does not resolve the connection issue, factory service may be required. back...

Can drift of the values happen?

The long-term lack of repeatability can be caused by fouling of the sensor, shifts in the calibration of the system or damaged sensors. back...

Is the OTT CTD only for groundwater applications?

No. The instrument can be used in surface and groundwater applications. The water level can be measured as depth to water or water level. back...

Can I attach a telemetry device to OTT CTD unit?

Yes, the OTT ITC communication device can be easily attached. It supports GSM, GSM/SMS and GSM/GPRS communication. back...

What can I do when the data communication from PC/Laptopto the OTT CTD fails?

Please check if the batteries are ok. If empty exchange batteries. After the batteries are placed in the communication unit, the OTT CTD system will reboot incl. memory verification check - this can take up to seven minutes.
If the batteries are ok, please check if the interfaces and COM settings are ok. back...

Is the OTT CTD applicable for very contaminated groundwater e.g. landfills- where oil or other contaminants are present?

The material of the CTD is highly corrosion resistant - please use the material data sheet to clarify if the deployment conditions are acceptable. Please consider that above described environmental conditions can influence the measurement and its results. back...

When should an OTT CTD be used?

The OTT CTD measures the level, temperature and electrical conductivity of (ground)water. An OTT CTD can be used in situations of increasing or decreasing contamination or salinisation of the groundwater.

Typical applications:

Aquifer storage and recovery

Saltwater intrusion monitoring

Deep saline aquifer studies

Wetlands restoration projects

Irrigation return flows

Mine water quality analysis

Road salt runoff studies

Surface water testing

Tide gauge monitoring

Tracer studies

Estuary studies

Riverbank filtration/infiltration

Remediation projects back...

What is conductivity?

Conductivity is inversely related to the resistance of a solution. Conductivity is the ratio of the electric current density to the electric field in a material, also known as electrical conductivity. In limnology, conductivity is a measure to the ability of water to pass an electrical current. Compensation of this measurement to 25°C constitutes specific conductance. This parameter indicates the amount of dissolved substances (salt). Salts and their concentration dictate osmoregulatory (salt balancing) functions in plants and animals. The ionic strength of water also regulates the toxicity of many substances. back...

What is the difference between conductivity and specific conductance?

Specific conductance is the scientific term for conductivity values that have been compensated to 25°C.
Electrical conductivity is a measure of a water's ability to conduct electricity, and therefore a measure of the water's ionic activity and content. The higher the concentration of ionic (dissolved) constituents, the higher the conductivity. Conductivity of the same water changes substantially as its temperature changes. This can have a confounding effect on attempts to compare this feature across different waters, or seasonal changes in this parameter for a particular body of water. The use of specific conductance, the conductivity normalized to a temperature of 25°C, eliminates this complication and allows valuable comparisons to be made. back...

How is salinity measured using this sensor?

Salinity is a value that is derived mathematically from the conductivity readings. The OTT CTD uses an algorithm from the USGS Water Supply Paper 2311, titled "Specific Conductance: Theoretical Considerations and Application to Analytical Quality Control" as the default. Users also have the option to choose the algorithm described in section 2520 B, or "Standard Methods for the Examination of Water and Wastewater". back...

How do you determine total dissolved solids (TDS)?

Total Dissolved Solids is also derived mathematically from the conductivity readings. The default factor for TDS calculations is 0.64. However, this can be user defined if historical data for a specific water body dictates the need for a different factor. back...

Can I do a specific conductance parameter setup?

Yes, with the OTT CTD it is possible to select specific conductance functions (freshwater, saltwater Standard 2510, ISO 7888/EN 27888 and none. back...

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