SBE 45 MicroTSG Thermosalinograph
The externally powered SBE 45, typically mounted near the ship’s seawater intake, accurately determines sea surface temperature and conductivity from underway vessels. Measured data and derived variables (salinity, sound velocity) are output in real-time in engineering units.
As an option, the SBE 45 connects to an AC-powered interface box near a computer. The interface box provides power and an isolated data interface; it contains a NMEA 0183 port for appending navigation data, and a port for appending the output of an optional remote temperature sensor (SBE 38). The SBE 38, installed at the seawater intake (ideally near the bow), measures sea surface temperature with minimal thermal contamination from the hull.
- Conductivity and Temperature at user-programmable intervals.
- Optional interface box for appending navigation data and remote temperature sensor (SBE 38) data.
- No memory, powered externally.
- RS-232 interface.
- Expendable anti-foulant device for bio-fouling protection.
- Sensor assembly easily removed for cleaning.
- Seasoft© V2 Windows software package (setup, and data acquisition and processing).
- Five-year limited warranty.
- Unique internal-field conductivity cell eliminates proximity effects. This is critically important for thermosalinographs, where the cell operates in a water jacket’s confined volume, and also permits use of expendable anti-foulant devices, for long-term bio-fouling protection.
- Aged and pressure-protected thermistor has a long history of exceptional accuracy and stability.
1. Seasave also supports acquisition of data from a NMEA device connected directly to computer.
2. Some installations require a de-bubbler. Click here for information on a de-bubbler produced by the State University of New York, Ocean Instrument Laboratory; information provided for reference only.
System Schematic: MicroTSG with Interface Box
& Remote Temperature Sensor
|Conductivity||0 to 7 S/m|
|Temperature||-5 to +35 °C|
|Temperature, SBE 38 remote||-5 to +35 °C|
|Conductivity||± 0.0003 S/m|
|Temperature||± 0.002 °C|
|Temperature, SBE 38 remote||± 0.001 °C|
|Conductivity||0.0003 S/m per month|
|Temperature||0.0002 °C per month|
|Temperature, SBE 38 remote||0.001 °C per month|
|Temperature, SBE 38 remote||0.0003 °C|
|Sample Interval||user-programmable 1-sec to 9-hour intervals (minimum dependent on setup; see manual)|
|Input Power||8 - 30 VDC|
|Power Draw||Acquisition: 34 mA at 8 VDC; 30 mA at 12-30 VDC
Quiescent: 10 microAmps
|Recommended Flow Rate||10 to 30 ml/sec (0.16 to 0.48 gal/min)|
|Operating Pressure||34.5 decibars (50 psi) maximum|
|Materials & Weight||PVC housing; 4.6 kg|
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.
What are the typical data processing steps recommended for each instrument?
Section 3: Typical Data Processing Sequences in the SBE Data Processing manual provides typical data processing sequences for our profiling CTDs, moored CTDs, and thermosalinographs. Typical values for aligning, filtering, etc. are provided in the sections detailing each module of the software. This information is also documented in the software's Help file. To download the software and/or manual, go to SBE Data Processing.
How often do I need to have my instrument and/or auxiliary sensors recalibrated? Can I recalibrate them myself?
- 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.
- 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.
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.
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.
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 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:
- Thoroughly clean the connector with water, followed by alcohol.
- 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.
- 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), 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.
- 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 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*|
*Note: Consult instrument manual for baud rates supported for your instrument.
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.
MicroTSG (Thermosalinograph) - In PVC flow-through housing. Requires 8-30 VDC input power. Includes RS-232 interface, 2.4 m data I/O & power input cable (801392), AF24173 Anti-Foulant Devices, spare o-ring & hardware kit, Seasoft software, & complete documentation.
|SBE 45 Remote Sea Surface Temperature Sensor and NMEA (GPS) Data Interface Options|
|38.110x||SBE 38 Digital Oceanographic Remote Seawater Intake Thermometer (titanium housing, XSG connector)||Optional 90402.1 Interface Box supports input from remote SBE 38 thermometer through 4-pin SBE 38 connector, providing sea surface temperature. Ideal location for SBE 38 is on pipe near seawater intake, as close to ship's bow as possible, to minimize water temperature changes due to ship's thermal mass. User can add SBE 38 to system at any time. 38.110x includes only SBE 38; order interface box, mount kit (50244), & interface cable (80438, 80456, or 80458) separately.|
|90402.1||SBE 45 Power, Navigation & Remote Temperature Interface box with AC power cord, DC input connector, 3 m computer serial cable (RS-232), 2.4 m SBE 45 interface cable, & NMEA test cable||
Interface Box comes with:
|50244||Stainless steel/plastic pipe coupling mounting kit for SBE 38 remote sensor (1 inch female NPT thread) with dummy sensor plug||Ideal location for SBE 38 is on pipe near seawater intake, as close to ship's bow as possible, to minimize water temperature changes due to ship's thermal mass. User can add SBE 38 to system at any time. Shown below is SBE 38 installed in 50244 mounting kit; see document 67071.
|80438||SBE 38 remote temperature cable for 90402 Interface Box, RMG-4FS to 4-pin MS3106A connector, 10 m (DN 31063)||Connects SBE 38 remote temperature sensor to 90402 Interface Box.|
|80456||SBE 38 remote temperature cable for 90402 Interface Box, RMG-4FS to 4-pin MS3106A connector, 30 m (DN 31063)|
|80458||SBE 38 remote temperature cable for 90402 Interface Box, RMG-4FS to 4-pin MS3106A connector, 50 m (DN 31063)|
|SBE 45 Spares & Accessories|
|801392||Data I/O cable, SBE 45 (MCIL-4MP) to computer (DB-9S), 2.4 m (DN 32756)||Connects SBE 45 to computer. Included with standard shipment; this is spare.|
|801216||Data I/O cable, SBE 45 (MCIL-4MP) to 90402 interface box, 2.4 m (DN 32397)||Connects SBE 45 to 90402 Interface Box. 801216 (2.4 m) included with Interface Box; these are spares.|
|801416||Data I/O cable, SBE 45 (MCIL-4MP) to 90402 interface box, 10 m (DN 32397)|
|801417||Data I/O cable, SBE 45 (MCIL-4MP) to 90402 interface box, 30 m (DN 32397)|
|801418||Data I/O cable, SBE 45 (MCIL-4MP) to 90402 interface box, 50 m (DN 32397)|
|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.|
|801422||NMEA test cable, DB-9S to MS3106A, SBE 11p/33/36/45, 1.8 m (DN 32786)||Connects NMEA on 90402 Interface Box to computer simulating NMEA input for testing NMEA interface. Included with 90402 Interface Box; this is spare. NMEA simulation program, NMEATest, is part of Seasoft software, & is installed when you install SBE Data Processing.|
|801542||AF24173 Anti-Foulant Device pair (spare, bagged, labeled for shipping)||Anti-foulant device fits into anti-foulant device cup at end of conductivity cell. 1 anti-foulant device 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.
|60036||SBE 45 Spare O-ring/hardware kit||See document 67095.|
|70410||Debubbler, Vortex, MSRC VDB-1, 2"||Some installations require a de-bubbler. Click here for information on this de-bubbler, which is produced by the State University of New York, Ocean Instrument Laboratory.|
- 801392 To computer COM port, 2.4 m, DN 32756
- 801216 To PN 90402 - SBE 45 Interface Box, 2.4 m, DN 32397
- 171887 To computer COM port (from PN 90402 - SBE 45 Interface Box PC), 3 m
- 80437 To SBE 38 with XSG connector (from PN 90402 - SBE 45 Interface Box SBE 38), 2.4 m, DN 31063
- 80438 To SBE 38 with XSG connector (from PN 90402 - SBE 45 Interface Box SBE 38), 10 m, DN 31063
- 801422 To NMEA simulation computer COM port (from PN 90402 - SBE 45 Interface Box NMEA), 1.8 m, DN 32786
- 17015 To AC power supply from PN 90402 - SBE 45 Interface Box (U.S. Standard)
- For SBE 38 on seawater intake pipe leading to SBE 45
50244 Thermosalinograph Stainless Remote Temperature Sensor Mount Kit (document 67071)
- 801542 AF24173 Anti-Foulant Device (pair, bagged, labeled for shipping)
- 60036 Hardware & O-ring kit for SBE 45 (document 67095)
Compare Shipboard Thermosalinographs (Conductivity & Temperature)
|SBE 21 SeaCAT Thermosalinograph||T, C||4||1000||64 Mb||RS-232|
|SBE 45 MicroTSG Thermosalinograph||T, C||10-30||*||*||RS-232|
|C = conductivity, T = temperature
* With optional PN 90402 SBE 45 Power, Navigation, and Remote Temperature Interface Box