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HydroCAT-EP

Measures conductivity, temperature, depth, dissolved oxygen, pH, turbidity, and chlorophyll. It is ideally suited for extended deployments in remote, biologically rich environments, for depths to 350 m.

Factory calibration and streamlined reference checks enable users to generate scientifically defensible data with minimal time and cost required for field maintenance. A five-year warranty and a set annual service cost means users can easily predict and plan for their service costs during the first five years of use. Ideally suited for long term deployments, the HydroCAT-EP can be easily integrated with external data loggers and telemetry systems.

Specifically designed for long-term deployments in remote, biologically rich environments, it comes equipped with multiple anti-fouling systems. Most sensors, including pH, are protected within the unique internal flow path by EPA approved anti-foulant devices. An integral pump minimizes the sensors' exposure to environmental waters, significantly reducing the impact of bio-fouling on sensor performance and drift. A copper faceplate and wiper protect the combination chlorophyll and turbidity sensor.

The HydroCAT-EP uses Sea-Bird Scientific UCI. This easy to use software can also be used with the SUNA V2 Nitrate Sensor.  Multiple task wizards and features like an automatic battery endurance calculator make it easy for anyone from novice water-quality professionals to senior experts to quickly learn how to use it.

Looking for the HydroCAT (alternative instrument without pH, Chlorophyll, or Turbidity)? Click here.

Measurement Range

Conductivity 0 to 70 mS/cm (0 to 70,000 μS/cm)
Temperature -5 to +45 °C
Optional Pressure 0 to 20 / 100 / 350 m (meters of deployment depth capability)
Optional Dissolved Oxygen 200% of surface saturation in all natural waters (fresh and salt)
pH 0 - 14 pH
Optional Turbidity 0 - 3,000 NTU
Optional Chlorophyll 0 - 400 µg/L

Initial Accuracy

Conductivity ± 0.003 mS/cm (3 μS/cm)
Temperature ± 0.002 °C (-5 to +35 °C); ± 0.01 (+35 to +45 °C)
Optional Pressure ± 0.1% of full scale range
Optional Dissolved Oxygen larger of ± 0.14 ml/L (equivalent to 0.2 mg/L) or ±2%
pH ± 0.1 pH
Optional Turbidity ± 1%
Optional Chlorophyll ± 3%

Typical Stability

Conductivity 0.003 mS/cm (3 μS/cm) per month
Temperature 0.0002 °C per month
Optional Pressure 0.05% of full scale range per year
Optional Dissolved Oxygen < 0.03 ml/L / 100,000 samples (20°C) (equivalent to 0.0429 mg/L)
pH 0.1 pH over 90 days
Optional Turbidity -
Optional Chlorophyll -

Resolution

Conductivity 0.0001 mS/cm (0.1 μS/cm)
Temperature 0.0001 °C
Optional Pressure 0.002% of full scale range
Optional Dissolved Oxygen 0.005 ml/L (equivalent to 0.07245 mg/L)
pH 0.01 pH
Optional Turbidity 0.06 - 0.17 based on range
Optional Chlorophyll 0.007 - 0.037 based on range

Miscellaneous

Input 9 - 24 VDC
Internal Battery 7.8 Amp hour
Communication Interface RS 232 / SDI 12
Data Memory 16 MB FLASH
Housing, Depth Rating, & Weight Plastic, 350 m

 

The list below includes (as applicable) the current product brochure, manual, and quick guide; software manual(s); and application notes.

For older HydroCAT-EP product manuals, organized by instrument firmware version, click here.

Title Type Publication Date PDF File
HydroCAT-EP Datasheet Product Datasheet Monday, June 19, 2017 datasheet-hydrocat-ep.pdf
HydroCAT-EP Manual Product Manual Thursday, August 24, 2017 HydroCAT-EPV5En.pdf
Sea-Bird pH Sensors Product Brochure Wednesday, April 26, 2017 4-Page-Web-Seabird_pH-APR-2017.pdf
HydroCAT-EP Manual (Español) Product Manual Thursday, August 24, 2017 HydroCAT-EPV5Es.pdf
HydroCAT-EP Quick Guide Product Quick Guide Monday, February 13, 2017 HydroCAT_EP_referencesheet_003.pdf
UCI Manual Software Manual Wednesday, September 6, 2017 UCI-1.2-User-Manual.pdf
Compare Integrated pH Sensors Technical Note Tuesday, August 2, 2016 pH-HydroCAT-EPvsSeapHOx.pdf
Long-Term Water Quality Monitoring Deployments With The Sea-Bird Hydrocat-EP White Paper Thursday, May 25, 2017 HydroCATEPCaseStudyMay2017.pdf
AN02D: Instructions for Care and Cleaning of Conductivity Cells Application Notes Monday, June 13, 2016 appnote2DJun16.pdf
Defensible Data with Less Time and Effort Application Article Tuesday, January 31, 2017 Defensible-Data-with-Less-Time-and-Effort_0.pdf
Long Term pH Monitoring Application Article Tuesday, January 31, 2017 Long-Term-pH-Monitoring.pdf
AN27D: Minimizing Strain Gauge Pressure Sensor Errors Application Notes Wednesday, May 18, 2016 appnote27DMay16.pdf
AN31: Computing Temperature and Conductivity Slope and Offset Correction Coefficients from Laboratory Calibrations and Salinity Bottle Samples Application Notes Monday, June 13, 2016 appnote31Jun16.pdf
Swapping/ Installing pH Sensor Technical Note Tuesday, January 31, 2017 HydroCAT-pH-Installation.pdf
AN69: Conversion of Pressure to Depth Application Notes Monday, July 1, 2002 appnote69.pdf
AN73: Using Instruments with Pressure Sensors at Elevations Above Sea Level Application Notes Wednesday, April 12, 2017 appnote73Apr17.pdf
AN83: Deployment of Moored Instruments Application Notes Wednesday, April 12, 2017 appnote83Apr17.pdf

UCI

UCI is a graphical software application that makes setup, operation, and in-field reference checks easy and robust. UCI is the recommended software for interacting with HydroCAT, HydroCAT-EP, SUNA, and Deep SUNA.
Version 1.2.2 released September 7, 2017

UCI 1.2.2 is now available for Apple Mac OS X / macOS. UCI now supports Deep SUNA. Please use the latest UCI for all SUNA interaction. SUNACom is now deprecated and is no longer maintained.

UCI-1.2.2-b192-x86.exe for Windows 7/8/10
UCI-1.2.2-176-macos-x86_64.pkg for Mac OS X / macOS

How can I tell if the conductivity cell on my CTD is broken?

Conductivity cells are made of glass, which is breakable.

  • If a cell is cracked, it typically causes a salinity shift or erratic data.
  • However, if the crack occurs at the end of the cell, the sensor will continue to function normally until water penetrates the epoxy jacket. Post-cruise calibration results will reveal whether or not water has penetrated the epoxy jacket.

Inspect the cell thoroughly and make sure that it isn’t cracked or abused in any way.

  • (SBE 9plus, 25, or 25plus) If the readings are good at the surface but erratic at depth, it is likely that the problem is in the cable or the connector, not the conductivity cell. Check the connections, making sure that you burp the connectors when you plug them in (see Application Note 57: Connector Care and Cable Installation). Check the cable itself (swap with a spare cable, if available).
  • If the readings are incorrect at the surface but good after a few meters, it is likely that the problem is flow-related. Verify that the pump is working properly. Check the air bleed valve (the white plastic piece in the Y-fitting, which is installed on vertically deployed CTDs) to see if it is clogged; clean out the small hole with a piece of fine wire supplied with your CTD.
  • If the readings are incorrect for the entire cast, there may be an incorrect calibration coefficient or the cell may be cracked.
  • Check the conductivity calibration coefficients in the configuration (.con or .xmlcon) file.
  • Do a frequency check on the conductivity cell. Disconnect the plumbing on the cell. Rinse the cell with distilled or de-ionized water and blow it dry (use your mouth and not compressed air, as there tends to be oil in the air lines on ships). With the cell completely dry, check the frequency reading. It should read within a few tenths of a Hz of the 0 reading on your Calibration Sheet. If it does not, something is wrong with the cell and it needs to be repaired.

What are the major steps involved in deploying a moored instrument?

Application Note 83: Deployment of Moored Instruments contains a checklist, which is intended as a guideline to assist you in developing a checklist specific to your operation and instrument setup.

What are the recommended practices for connectors - mating and unmating, cleaning corrosion, and replacing?

Mating and Unmating Connectors:

It is important to prepare and mate connectors correctly, both in terms of the costs to repair them and to preserve data quality. Leaking connectors cause noisy data and even potential system shutdowns. Application Note 57: Connector Care and Cable Installation describes the proper care and installation of connectors for Sea-Bird instruments. The Application Note covers connector cleaning and cable or dummy plug installation, locking sleeve installation, and cold weather tips.

Checking for Leakage and Cleaning Corrosion on Connectors:

If there has been leakage, it will show up as green-colored corrosion product. Performing the following steps can usually reverse the effect of the leak:

  1. Thoroughly clean the connector with water, followed by alcohol.
  2. Give the connector surfaces a light coating of silicon grease.

Re-mate the connectors properly — see Application Note 57: Connector Care and Cable Installation and 9-minute video covering O-ring, connector, and cable maintenance.

Replacing Connectors:

  • The main concern when replacing a bulkhead connector is that the o-rings on the connector and end cap must be prepared and installed correctly; if they are not, the instrument will flood. See the question below for general procedure on handling o-rings.
  • Use a thread-locking compound on the connector threads to prevent the new connector from loosening, which could also lead to flooding.
  • If the cell guard must be removed to open the instrument, take extra care not to break the glass conductivity cell.

What is an Anti-Foulant Device? Does it affect the conductivity cell calibration? How often should I replace it? Does it require special handling?

The Anti-Foulant Device is an expendable device that is installed on each end of the conductivity cell, so that any water that enters the cell is treated. Anti-Foulant Devices are typically used with moored instruments (SBE 16, 16plus, 16plus-IM, 16plus V2, 16plus-IM V2, 37-SM, 37-SMP, 37-SMP-IDO, 37-SMP-ODO, 37-SI, 37-SIP, 37-SIP-IDO, 37-IM, 37-IMP, 37-IMP-IDO, 37-IMP-ODO, HydroCAT, HydroCAT-EP), thermosalinographs (SBE 21 and 45), glider CTDs (Glider Payload CTD), moored profilers (SBE 52-MP), and drifters (SBE 41/41CP Argo float CTDs), and optionally with SBE 19plus, 19plus V2, and 49 profilers.

Anti-Foulant Devices have no effect on the calibration, because they do not affect the geometry of the conductivity cell in any way. The Anti-Foulant Devices are mounted at either end of the conductivity cell. For an in-depth explanation of how Sea-Bird makes the conductivity measurement, see Conductivity Sensors for Moored and Autonomous Operation.

Useful deployment life varies, depending on several factors. We recommend that customers consider more frequent anti-foulant replacement when high biological activity and strong current flow (greater dilution of the anti-foulant concentration) are present. Moored instruments in high growth and strong dilution environments have been known to obtain a few months of quality data, while drifters that operate in non-photic, less turbid deep ocean environments may achieve years of quality data. Experience may be the strongest determining factor in specific deployment environments. Sea-Bird recommends that you keep track of how long the devices have been deployed, to allow you to purchase and replace the devices when needed.

Note that the anti-foulant device does not actually dissolve, so there is no way to visually determine if the anti-foulant device is still effective.

The cost of the anti-foulant devices is small compared to the deployment costs, so we recommend that you replace the devices before each deployment. This will provide the maximum bio-fouling protection, resulting in long-term data quality. 

Shelf Life and Storage: The best way to store Anti-Foulant Devices is in an air-tight, opaque container. The rate of release of anti-foulant is based on saturation of the environment. The anti-foulant will release until the environment is fully saturated (100% saturated) and then it will no longer release any anti-foulant. So if you keep Anti-Foulant Devices sealed well in an air-tight container, theoretically they will stay good for extended periods of time. Exposure to direct sunlight can also affect the release of anti-foulant; we recommend storage in an opaque container.

Handling:

  • For details, refer to the Material Safety Data Sheet, enclosed with the shipment and available on our MSDS page.
  • Anti-Foulant Devices are not classified by the U.S. DOT or the IATA as hazardous material.

What are the recommended practices for storing sensors at low temperatures, and deploying at low temperatures or in frazil or pancake ice?

General

Large numbers of Sea-Bird conductivity instruments have been used in Arctic and Antarctic programs.

Special accommodation to keep temperature, conductivity, oxygen, and optical sensors at or above 0 C is advised. Often, the CTD is brought inside protective doors between casts to achieve this.

Conductivity Cell

When freezing is possible, we recommend that the conductivity sensor be stored dry. Remove larger droplets of water by blowing through the cell. Do not use compressed air, which typically contains oil vapor. Attach a length of Tygon tubing to each end of the conductivity cell to close the cell ends. See Application Note 2D: Instructions for Care and Cleaning of Conductivity Cells for details.

There are several considerations to weigh when contemplating deployments at low temperatures in general, and in frazil or pancake ice:

  • Ensure that the instrument is at or above water temperature before it is deployed. If the cell gets colder than 0 to -2 ºC while on deck, when it enters the water a layer of ice forms inside the cell as the cell warms to ocean temperature. If ice forms inside the conductivity cell, measurements will be low of correct until the ice layer melts and disappears. Thin layers of ice will not hurt the conductivity cell, but repeated ice formation on the electrodes will degrade the conductivity calibration (at levels of 0.001 to 0.020 psu) and thicker layers of ice can lead to glass fracture and permanent damage of the cell.
  • For accurate measurements, keep ice out of the sensing region of the conductivity cell. The conductivity measurement involves determining the electrical resistance of the water inside the sensor. Ice is essentially a non-conductor. To the extent that ice displaces the water, the conductivity will register (very) misleadingly low. Some type of screening is necessary to keep ice out of the cell. This is relatively easy to arrange for the Sea-Bird conductivity cell, which is an electrode-type cell, because its sensing region is totally inside a long tube; plastic mesh could be positioned at each end and would have zero effect on accuracy and stability.

The above considerations apply to all known conductivity sensor types, whether electrode or inductive types. 

If deploying at low temperatures but no surface frazil or pancake ice is present, rinse the conductivity cell in one of the following salty solutions (salty water depresses the freezing point) to prevent freezing during deployment. But this does not mean you can store the cell in one of these solutions outside . . . it will freeze.

  • Solution of 1% Triton in sterile seawater (use 0.5-micron filtered seawater or boiled seawater),   or
  • Brine solution (distilled seawater or homemade salt solution that is higher than 35 psu in salinity).

Note that there is still a risk of forming ice inside the conductivity cell if deploying through frazil or pancake ice on the surface, if the freezing point of the salt water is the same as the water temperature. Therefore, we recommend that you deploy the conductivity cell in a dry state for these deployments.

Commercially available alcohol or glycol antifreezes contain trace amounts of oils that will coat the conductivity cell and the electrodes, causing a calibration shift, and consequently result in errors in the data. Do not use alcohol or glycol in the conductivity cell.

Temperature Sensor

In general, neither the accuracy of the temperature measurement nor the survival of the temperature sensor will be affected by ice.

Oxygen Sensor

For the SBE 43 and SBE 63 Dissolved Oxygen sensor, avoid prolonged exposure to freezing temperature, including during shipment. Do not store with water (fresh or seawater), Triton solution, alcohol, or glycol in the plenum. The best precaution is to keep the sensor indoors or in some shelter out of the cold weather.

Does it matter if I deploy my moored instrument, which includes a conductivity sensor, in a horizontal or vertical position?

Yes, vertical is usually preferable. In the presence of consistent currents and suspended sediment, we have seen instances where a horizontal conductivity cell is scoured by the abrasive effect of the flow. When scouring is particularly intense, the electrodes can be stripped of their electroplated platinum-black coating, driving the calibration toward fresher readings. Sedimentation (silting) in the cell also drives the readings fresh of correct.

Mounting the instrument vertically avoids abrasive flow and sediment build-up while allowing wave motions and Bernoulli pressures to flush the cell.

Note that some moored sensors (SBE 37-SIP37-SIP-IDO, 37-SMP37-SMP-IDO37-SMP-ODO37-IMP37-IMP-IDO37-IMP-ODO, HydroCAT, HydroCAT-EP) have a recommended orientation because of their u-shaped plumbing configuration. Refer to the instrument manual for details.

Is it necessary to put my instrument in water to test it? Will I destroy the conductivity cell if I test it in air?

It is not necessary to put the instrument in water to test it. It will not hurt the conductivity cell to be in air.

If there is a pump on the instrument, it should not be run for extended periods in air.

  • Profiling instruments (SBE 9plus, 19, 19plus, 19plus V2, 25, 25plus, 49, GPCTD) and some moored instruments (all pumped MicroCATs with integral dissolved oxygen (DO), pumped MicroCATs without DO with firmware 3.0 and later, and all HydroCATs and HydroCAT-EPs) do not turn on the pump unless the conductivity frequency is above a specified minimum value (minimum value is hard-wired in 9plus, user-programmable in other instruments). This prevents the pump from turning on in air. See the instrument manual for details.
  • If your instrument does not check for conductivity frequency before turning on the pump: 
    - For moored SeaCATs (16, 16plus, 16plus-IM, 16plus V2, 16plus-IM V2): Disconnect the pump cable for the test. 
    - For older pumped MicroCATs: orient the MicroCAT to provide an upright U-shape for the plumbing. Then fill the inside of the pump head with water via the pump exhaust tubing; this will provide enough lubrication to prevent pump damage during brief testing.

Can I use a pressure sensor above its rated pressure?

Digiquartz pressure sensors are used in the SBE 9plus, 53, and 54. The SBE 16plus V2, 16plus-IM V2, 19plus V2, and 26plus can be equipped with either a Druck pressure sensor or a Digiquartz pressure sensor. All other instruments that include pressure use a Druck pressure sensor.

  • The overpressure rating for a Digiquartz (as stated by Paroscientific) is 1.2 * full scale. The sensor will provide data values above 100% of rated full scale; however, Sea-Bird does not calibrate beyond the rated full scale.
  • The overpressure rating for a Druck (as stated by Druck) is 1.5 * full scale. The sensor will provide data values above 100% of rated full scale; however, Sea-Bird does not calibrate beyond the rated full scale.

Note: If you use the instrument above the rated range, you do so at your own risk; the product will not be covered under warranty.

How should I handle my CTD to avoid cracking the conductivity cell?

Shipping: Sea-Bird carefully packs the CTD in foam for shipping. If you are shipping the CTD or conductivity sensor, carefully pack the instrument using the original crate and packing materials, or suitable substitutes.

Use: Cracks at the C-Duct end of the conductivity cell are most often caused by:

  • Hitting the bottom, which can cause the T-C Duct to flex, resulting in cracking at the end of the cell.
  • Removing the soaker tube from the T-C duct in a rough manner, which also causes the T-C Duct to flex. Pulling the soaker tube off at an angle can be especially damaging over time to the cell. Pull the soaker tube off straight down and gently.
  • Improper disassembly of the T-C ducted temperature and conductivity sensors (SBE 25, 25plus, and 9plus) when removing them for shipment to Sea-Bird for calibration. See Shipping SBE 9plus, 25, and 25plus Temperature and Conductivity Sensors for the correct procedure.

Note: If a Tygon tube attached to the conductivity cell has dried out, yellowed, or become difficult to remove, slice (with a razor knife or blade) and peel the tube off of the conductivity cell rather than twisting or pulling the tube off.

How do instruments handle external power if internal batteries are installed?

Most Sea-Bird instruments that are designed to be powered internally or externally incorporate diode or'd circuitry, allowing only the voltage that has the greater potential to power the instrument. You can power the instrument externally without running down the internal batteries. This allows you to lab test using external power that has higher voltage than the internal batteries, and then deploy using internal power, knowing that the internal batteries are fresh.

For the SBE 25plus, if external power of 14 volts or higher is applied, the 25plus runs off of the external power, even if the main battery voltage is higher.

How should I pick the pressure sensor range for my CTD? Would the highest range give me the most flexibility in using the CTD?

While the highest range does give you the most flexibility in using the CTD, it is at the expense of accuracy and resolution. It is advantageous to use the lowest range pressure sensor compatible with your intended maximum operating depth, because accuracy and resolution are proportional to the pressure sensor's full scale range. For example, the SBE 9plus pressure sensor has initial accuracy of 0.015% of full scale, and resolution of 0.001% of full scale. Comparing a 2000 psia (1400 meter) and 6000 psia (4200 meter) pressure sensor:

  • 1400 meter pressure sensor ‑ initial accuracy is 0.21 meters and resolution is 0.014 meters
  • 4200 meter pressure sensor ‑ initial accuracy is 0.63 meters and resolution is 0.042 meters

What is the maximum cable length for real-time RS-232 data?

Cable length is one of the most misunderstood items in the RS-232 world. The RS-232 standard was originally developed decades ago for a 19200 baud rate, and defines the maximum cable length as 50 feet, or the cable length equal to a capacitance of 2500 pF. The capacitance rule is often forgotten; using a cable with low capacitance allows you to span longer distances without going beyond the limitations of the standard. Also, the maximum cable length mentioned in the standard is based on 19200 baud rate; if baud is reduced by a factor of 2 or 4, the maximum length increases dramatically. Using typical underwater cables, allowable combinations of cable length and baud rate for Sea-Bird instruments communicating with RS-232 are shown below:

Maximum Cable Length (meters) Maximum Baud Rate*
1600 600
800 1200
400 2400
200 4800
100 9600
50 19,200
25 38,400
16 57,600
8 115,200

*Note: Consult instrument manual for baud rates supported for your instrument.

 

How often do I need to have my instrument and/or auxiliary sensors recalibrated? Can I recalibrate them myself?

General recommendations:

  • Profiling CTD — recalibrate once/year, but possibly less often if used only occasionally. We recommend that you return the CTD to Sea-Bird for recalibration. (In principle, it is possible for calibration to be performed elsewhere, if the calibration facility has the appropriate equipment andtraining. However, the necessary equipment is quite expensive to buy and maintain.) In between laboratory calibrations, take field salinity samples to document conductivity cell drift.
  • Moored CTD — recalibrate at least once/year, but possibly more often depending on the degree of bio-fouling in the water.
  • Thermosalinograph — recalibrate at least once/year, but possibly more often depending on the degree of bio-fouling in the water.
  • DO sensor —
    — SBE 43 — recalibrate once/year, but possibly less often if used only occasionally and stored correctly (see Application Note 64), and also depending on the amount of fouling and your ability to do some simple validations (see Application Note 64-2)
    — SBE 63 — recalibrate once/year, but possibly less often if used only occasionally and stored correctly and also depending on the amount of fouling and your ability to do some simple validations (see SBE 63 manual)
  • pH sensor —
    — SBE 18 pH sensor or SBE 27 pH/ORP sensor — recalibrate at the start of every cruise, and then at least once/month, depending on use and storage
    — Satlantic SeaFET pH sensor — recalibrate at least once/year. See FAQ tab on Satlantic's SeaFET page for details (How often does the SeaFET need to be calibrated?).
  • Transmissometer — usually do not require recalibration for several years. Recalibration at the manufacturer’s factory is the most practical method.

Profiling CTDs:

We often have requests from customers to have some way to know if the CTD is out of calibration. The general character of sensor drift in Sea-Bird conductivity, temperature, and pressure measurements is well known and predictable. However, it is very difficult to know precisely how far a CTD calibration has drifted over time unless you have access to a very sophisticated calibration lab. In our experience, an annual calibration schedule will usually maintain the CTD accuracy to within 0.01 psu in Salinity.

Conductivity drifts as a change in slope as a result of accumulated fouling that coats the inside of the conductivity cell, reducing the area of the cell and causing an under-reporting of conductivity. Fouling consists of both biological growth and accumulated oils and inorganic material (sediment). Approximately 95% of fouling occurs as the cell passes through oil and other contaminants floating on the sea surface. Most conductivity fouling is episodic, as opposed to gradual and steady drift. Most fouling events are small and mostly transitory, but they have a cumulative affect over time. A severe fouling event, such as deployment through an oil spill, could have a dramatic but only partially recoverable effect, causing an immediate jump shift toward lower salinity. As fouling becomes more severe, the fit becomes increasingly non-linear and offsets and slopes no longer produce adequate correction, and return to Sea-Bird for factory calibration is required. Frequently checking conductivity drift is likely to be the most productive data assurance measure you can take. Comparing conductivity from profile to profile (as a routine check) will allow you to detect sudden changes that may indicate a fouling event and the need for cleaning and/or re-calibration.

Temperature generally drifts slowly, at a steady rate and predictably as a simple offset at the rate of about 1-2 millidegrees per year. This is approximately equal to 1-2 parts per million in Salinity error (very small).

Pressure sensor drift is also an offset, and annual comparisons to an accurate barometer to determine offset will generally keep the sensor within specification for several years, particularly as the sensors age over time.

How accurate is salinity measured by my CTD? What factors impact accuracy?

One of the reasons that this is not a simple question is that there are several factors to take into consideration regarding the error margin for practical salinity measurements. Salinity itself is a derived measurement from temperature, conductivity, and pressure, so any errors in these sensors can propagate to salinity. For example, our initial accuracy specification for the SBE 3plus temperature sensor and SBE 4 conductivity sensor on an SBE 9plus CTD is approximately equivalent to an initial salinity accuracy of 0.003 PSU (note that conductivity units of mS/cm are roughly equivalent in terms of magnitude to PSU).

However, another issue to consider is that this accuracy is defined for a clean, well-mixed calibration bath. In the ocean, some of the biggest factors that impact salinity accuracy are 1) sensor drift from biofouling or surface oils for conductivity in particular and 2) dynamic errors that can occur on moving platforms, particularly when conditions are rapidly changing, which will be true for all sensors that measure salinity. Sea-Bird provides recommendations, design features such as a pumped flow path, and data processing routines to align and improve data for the salinity calculation to account for thermal transients and hysteresis, and to match sensor response times.  Depending on the environment and the steepness of the gradient, and after careful data processing, this may continue to have an impact on salinity on the order of 0.002 PSU or more, for example. For more details, see Application Note 82.

Lastly, note that salinity in PSU is calculated according to the Practical Salinity Scale (PSS-78), which is defined as valid for salinity ranges from 2 – 42 PSU.

Do I need to remove batteries before shipping my instrument for a deployment or to Sea-Bird?

Alkaline batteries can be shipped installed in the instrument. See Shipping Batteries for information on shipping instruments with Lithium or Nickel-Metal Hydride (NiMH) batteries.

Do I need to clean the exterior of my instrument before shipping it to Sea-Bird for calibration?

Remove as much biological material and/or anti-foul coatings as possible before shipping. Sea-Bird cannot place an instrument with a large amount of biological material or anti-foul coating on the housing in our calibration bath; if we need to clean the exterior before calibration, we will charge you for this service.

  • To remove barnacles, plug the ends of the conductivity cell to prevent the cleaning solution from getting into the cell. Then soak the entire instrument in white vinegar for a few minutes. After scraping off the barnacles and marine growth, rinse the instrument well with fresh water.
  • To remove anti-foul paint, use a Heavy Duty Scotch-Brite pad (http://www.3m.com/us/home_leisure/scotchbrite/products/scrubbing_scouring.html) or similar scrubbing device.

I want to change the pressure sensor on my CTD, swapping it as needed to get the best data for a given deployment depth. Can I do this myself, or do I need to send the instrument to Sea-Bird?

On most of our instruments, replacement of the pressure sensor should be performed at Sea-Bird. We cannot extend warranty coverage if you replace the pressure sensor yourself.

However, we recognize that you might decide to go ahead and do it yourself because of scheduling/cost issues. Some guidelines follow:

  1. Perform the swap and carefully store the loose sensor on shore in a laboratory or electronics shop environment, not on a ship. The pressure sensor is fairly sensitive to shock, and a loose sensor needs to be stored carefully. Dropping the sensor will break it.
  2. Some soldering and unsoldering is required. Verify that the pressure sensor is mounted properly in your instrument. Properly re-grease and install the o-rings, or the instrument will flood.
  3. Once the sensor is installed, back-fill it with oil. Sea-Bird uses a vacuum-back filling apparatus that makes this job fairly easy. We can provide a drawing showing the general design of the apparatus, which can be modified and constructed by your engineers.
  4. For the most demanding work, calibrate the sensor on a deadweight tester to ensure proper operation and calibration.
  5. Enter the calibration coefficients for the new sensor in:
  • the CTD configuration (.con or .xmlcon) file, using Seasave V7 or SBE Data Processing, and
  • (for an instrument with internally stored calibration coefficients) the CTD EEPROM, using the appropriate terminal program and the appropriate calibration coefficient commands

Note: This discussion does not apply to the SBE 25 (not 25plus), which uses a modular pressure sensor (SBE 29) mounted externally on the CTD. Swap the SBE 29 as desired, use the CC command in Seaterm or SeatermAF to enter the new pressure range and pressure temperature compensation value, and type the calibration coefficients for the new sensor into the CTD configuration (.con or .xmlcon) file in Seasave V7 or SBE Data Processing.

Can I brush-clean and replatinize the conductivity cell myself? How often should this be done?

Brush-cleaning and replatinizing should be performed at Sea-Bird. We cannot extend warranty coverage if you perform this work yourself.

The brush-cleaning and replatinizing process requires specialized equipment and chemicals, and the disassembly of the sensor. If performed incorrectly, you can damage the cell. Additionally, the sensor must be re-calibrated when the work is complete.

Sea-Bird determines whether brush-cleaning and replatinizing is required based upon how far the calibration has drifted from the original calibration. Typically, a conductivity sensor on a profiling CTD requires brush-cleaning and replatinizing every 5 years.

I sent my conductivity sensor to Sea-Bird for calibration, and you also performed a Cleaning and Replatinizing (C &P). You sent the instrument back with 2 sets of calibration data. What does this mean?

The post-cruise calibration contains important information for drift calculations. The post-cruise calibration is performed on the cell as we received it from you, and is an indicator of how much the sensor has drifted in the field. Information from the post-cruise calibration can be used to adjust your data, based on the sensor’s drift over time. See Application Note 31: Computing Temperature and Conductivity Slope and Offset Correction Coefficients from Laboratory Calibrations and Salinity Bottle Samples.

If the sensor has drifted significantly (based on the data from the post-cruise calibration), Sea-Bird performs a C & P to restore the cell to a state similar to the original calibration. After the C & P, the sensor is calibrated again. This calibration serves as the starting point for future data, and for the sensor’s next drift calculation.

The C & P tends to return the cell to its original state. However, there are many subtle factors that may result in the post-C & P calibration not exactly matching the original calibration. Basically, the old platinizing is stripped off and new platinizing is plated on. Anything in this process that alters the cell slightly will result in a difference from the original calibration. We compare the calibration after C & P with the original calibration, not to make any drift analysis, but to make sure we did not drastically alter the cell, or that the cell was not damaged during the C & P process.

Family Model . Housing Pressure Sensor/Range SBE 63 Optical
Dissolved Oxygen
Turbidity &
Chlorophyll a
HC EP . 1 – 350 m (plastic) 0 – none 0 – none 0 – none
        1 – 20 m strain gauge 1 – yes 1 – yes
        2 – 100 m strain gauge    
        3 – 350 m strain gauge    

Example: HCEP.1311 is a HydroCAT-EP with 350 m housing, 350 m strain gauge pressure sensor, integrated SBE 63 Optical Dissolved Oxygen Sensor, and integrated Turbidity and Chlorophyll a sensor. See table below for description of each selection.

PART # DESCRIPTION NOTES
HCEP

HydroCAT-EP Conductivity, Temperature and pH (Depth, Chlorophyll, Turbidity and Optical Dissolved Oxygen optional) Recorder, Serial Interface, Memory and Internal Pump- Includes 350 meter plastic housing, 16 MB flash memory, RS-232/SDI-12 interface, external power input capability (power plus RS-232 serial on 6 pin MCBH wet-pluggable connector) lithium batteries (non-hazardous), AF24173 Anti-Foulant devices, data/power interface cable, UCI software, and complete documentation.

SDI-12 interface is in addition to RS-232 interface. Instrument can be set up via RS-232, using full set of commands, and then a more limited set of commands can be sent via SDI-12 to make small setup changes in the field.

HydroCAT-EP is intended for coastal applications.

HydroCAT-EP Pressure Sensor Range (depth) Selections MUST SELECT ONE
HCEP.10xx No pressure sensor Pressure sensor is not field replaceable / swappable. While highest pressure rating gives you most flexibility in using HycroCAT-EP, it is at expense of accuracy & resolution. It is advantageous to use lowest range pressure sensor compatible with your intended maximum operating depth, because accuracy & resolution are proportional to pressure sensor's full scale range. For example, comparing 100 & 350 m sensors:
  • 100 m sensor:
    initial accuracy = 0.1 m (= 0.1% * 100 m),
    resolution = 0.002 m (= 0.002% * 100 m)
  • 350 m sensor:
    initial accuracy =0.35 m (= 0.1% * 350 m),
    resolution = 0.007 m (= 0.002% * 350 m)
HCEP.11xx 20 m strain gauge pressure sensor
HCEP.12xx 100 m strain gauge pressure sensor
HCEP.13xx 350 m strain gauge pressure sensor
HydroCAT-EP Optical Dissolved Oxygen Sensor Selections MUST SELECT ONE
HCEP.1x0x No oxygen sensor  
HCEP.1x1x Optical dissolved oxygen sensor
HydroCAT-EP Turbidity and Chlorophyll a Selections MUST SELECT ONE
HCEP.1xx0 No Turbidity & Chlorophyll a sensor  
HCEP.1xx1 Turbidity & Chlorophyll a sensor with Wiper  
HydroCAT-EP Spares & Accessories
50616 Bail mounting kit
HC-pH Replacement pH sensor for HydroCAT-EP  
50647 pH teflon junction & electrolytes maintenance kit. Hydrolab part number 013410HY.  
SAS-541483 Replacement optical sensor (Turbidity & Chlorophyll a) for HydroCAT-EP  
SAS-542035 Solid secondary standard for use with HydroCAT-EP  
801542 AF24173 Anti-Foulant Device pair (spare, bagged, labeled for shipping) Anti-foulant devices fit into anti-foulant device cups at intake & exhaust. Anti-foulant devices included with standard shipment; these are spares.
Useful life varies, depending on several factors. We recommend that customers consider more frequent replacement when high biological activity & strong current flow (greater dilution of anti-foulant concentration) are present. Moored instruments in high growth & strong dilution environments have been known to obtain a few months of quality data, while drifters that operate in non-photic, less turbid deep ocean environments may achieve years of quality data. Experience may be strongest determining factor in specific deployment environments.
50441 HydroCAT-EP lithium batteries (spare), package of twelve 3.6V AA cells (Saft LS 14500)

One set of batteries is included with standard shipment; 50441 are spares. Batteries are easily accessed by removing 2 screws from connector end cap & pulling out end cap. Shipping restrictions apply for lithium batteries; see HydroCAT-EP manual for details. Click here to buy Saft LS 14500 from Amazon.

801863 is battery holder, without batteries. Battery holder is included with standard shipment; this is a spare.


801863 shown with 50441 cells installed
(Note: Cells cannot be shipped
installed in battery holder)


Cells packed in heat-sealed plastic (above),
then placed in bubble-wrap outer sleeve &
strong packaging for shipment (below)

801863 Yellow top battery holder (14V nominal, Version 2) for use with twelve 3.6V AA lithium cells
802220 Data/Power interface cable for RS-232 and SDI-12 interface, Wet-pluggable, MCIL-6FS to DB-9S & red/black twisted wire leads, 2.4 m (DN 33733) Included with standard shipment; this is spare.
20200 USB to Serial Port Adapter, FTDI UC232R-10 (connects computers with USB ports to RS-232 instruments) Many newer PCs & laptop computers have USB port(s) instead of RS-232 serial port(s). USB serial adapter plugs into USB port, & allows a serial device to be connected through adapter. Multi-port adapters are available from other companies; see Application Note 68.
802255 Data/Power polyurethane jacketed interface cable, 5 m, SDI-12, wet-pluggable, MCIL-6FS to DB-9S with red/black & yellow/black twisted wire leads (DN 33768)  
802256 Data/Power polyurethane jacketed interface cable, 10 m, SDI-12, wet-pluggable, MCIL-6FS to DB-9S with red/black & yellow/black twisted wire leads (DN 33768)
802257 Data/Power polyurethane jacketed interface cable, 15 m, SDI-12, wet-pluggable, MCIL-6FS to DB-9S with red/black & yellow/black twisted wire leads (DN 33768)
235192.01 Replacement copper intake plate. Replacement frequency is determined by remaining thickness when instrument is returned for service, this cost will not be included in annual service
Photo shows copper intake plate being removed

 

Cables

  • 802220 To computer COM port with power leads and leads to SDI-12 (from Wet-pluggable connector), 2.4 m, DN 33733

Mount Kits

  • 50616 Bail mounting kit

Spare Parts

Batteries

  • 801863 Yellow battery holder (14V nominal, Version 2) for use with twelve 3.6V AA lithium cells
  • 50441 HydroCAT lithium batteries, package of twelve 3.6V AA cells (Saft LS 14500) - Click here to buy Saft LS 14500 from Amazon.

Hardware & O-Ring Kits

  • 60074 Hardware & O-ring kit (document 67232)

Miscellaneous

  • 801542 AF24173 Anti-Foulant Device (pair, bagged, labeled for shipping)
  • 50640 HydroCAT-EP Reference Check Kit (procedure 67233)

Compare  Moored / Time Series Recording Instruments

SBE Measures
(C, T, P)
Auxiliary Sensors Memory Power Communication Real-Time
Data
Comments
Internal External
SBE 16plus V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb RS-232 Optional pump
SBE 16plus SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb RS-232 or -485 Replaced by SBE 16plus V2 in 2008
SBE 16 SeaCAT C-T (P) Recorder
C, T, P* 4 A/D 1 Mb RS-232 Replaced by SBE 16plus in 2001
SBE 16plus-IM V2 SeaCAT C-T (P) Recorder C, T, P* 6 A/D; 1 RS-232 64 Mb   Inductive Modem Optional pump
SBE 16plus-IM SeaCAT C-T (P) Recorder
C, T, P* 4 A/D; optional RS-232 or PAR 8 Mb   Inductive Modem Replaced by SBE 16plus-IM V2 in 2008
SBE 19plus V2 SeaCAT Profiler CTD C, T, P 6 A/D; 
1 RS-232
64 Mb RS-232 Programmable mode — profiling or moored
SBE 19plus SeaCAT Profiler CTD
C, T, P 4 A/D; optional PAR 8 Mb RS-232 Replaced by SBE 19plus V2 in 2008
SBE 19 SeaCAT Profiler CTD
C, T, P 4 A/D 1 - 8 Mb RS-232 Replaced by SBE 19plus in 2001
SBE 37-SM MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232 or -485  
SBE 37-SMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb RS-232, RS-485, or SDI-12 Integral pump
SBE 37-SMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb RS-232 or -485 Integral pump; Replaced by SBE 37-SMP-ODO in 2014
SBE 37-SMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb RS-232, RS-485, or SDI-12 Integral pump
HydroCAT C-T-(DO)-(P) Recorder C, T, P* Integrated Optical DO* 8 Mb RS-232 & SDI-12 Integral pump; for Coastal applications to 350 m
HydroCAT-EP
C-T-pH-(DO)-(P)-(Chl)-(NTU) Recorder
C, T, P* Integrated pH, Optical DO*, Chlorophyll*, Turbidity* 16 Mb RS-232 & SDI-12 Integral pump; for Coastal applications to 350 m
SeapHOx Ocean C-T-DO-pH (P) Recorder C, T, P* Integrated Optical DO, pH 8 Mb RS-232 37-SMP-ODO with SeaFET pH sensor; to 50 m
Deep SeapHOx Ocean C-T-DO-pH (P) Recorder C, T, P* Integrated Optical DO, pH 8 Mb RS-232 37-SMP-ODO with Deep SeaFET pH sensor; to 2000 m
SBE 37-IM MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem  
SBE 37-IMP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   Inductive modem Integral pump
SBE 37-IMP-IDO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated DO 8 Mb   Inductive modem Integral pump; Replaced by SBE 37-IMP-ODO in 2014
SBE 37-IMP-ODO MicroCAT C-T-DO (P) Recorder C, T, P* Integrated Optical DO 8 Mb   Inductive modem Integral pump
SBE 37-SI MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485  
SBE 37-SIP MicroCAT C-T (P) Recorder C, T, P*   8 Mb   RS-232 or -485 Integral pump

SBE 37-SIP-IDO MicroCAT C-T-DO (P) Sensor

C, T, P* Integrated DO 8 Mb   RS-232 or -485 Integral pump
SBE 39plus Temperature (P) Recorder T, P*   64 Mb Optional USB & RS-232 Optional  
SBE 39 Temperature (P) Recorder
T, P*   32 Mb Optional RS-232 Optional Replaced by SBE 39plus in 2014
SBE 39plus-IM Temperature (P) Recorder T, P*   64 Mb   Inductive Modem & USB  
SBE 39-IM Temperature (P) Recorder T, P*   32 Mb   Inductive modem Replaced by SBE 39plus-IM in 2016
SBE 56 Temperature Logger T   64 Mb   USB    
SBE 26plus Seagauge Wave & Tide Recorder T, P C optional 32 Mb RS-232
(tides, waves, & wave statistics)
Wave & tide recorder
SBE 26 Seagauge Wave & Tide Recorder
T, P C optional 8 Mb RS-232   Replaced by SBE 26plus in 2004
SBE 53 BPR Bottom Pressure Recorder T, P C optional 32 Mb RS-232 Bottom pressure recorder
SBE 54 Tsunameter Tsunami Pressure Sensor T, P   128 Mb Optional RS-232 Tsunami pressure sensor

C = conductivity, T = temperature, P = pressure, DO = dissolved oxygen
* = optional
products are no longer in production. Follow the links above to the product page to retrieve manuals and application notes for these older products.