Frequently Asked Questions (FAQs) --
Ordering

FAQs have been organized into the following categories:

Ordering questions (this page)

• How do I find information about the options available with each instrument?
• Where do I find pricing information for new instruments, calibration services, and/or repair services?
• Which Sea-Bird profiling CTD is best for my application?
• I want to integrate a moored CTD with some auxiliary sensors (transmissometer, fluorometer, etc.). Which CTD should I use?
• How should I pick the pressure sensor range for my CTD? Would the highest range give me the most flexibility in using the CTD?
• I am ordering a CTD and want to use auxiliary sensors. Should I order them from Sea-Bird also, or deal directly with the sensors' manufacturers?
• What are the pros and cons of ordering wet-pluggable connectors?
• Can Sea-Bird provide some guidance for ordering cable, winch, and deck gear?

	General instrument questions How do instruments handle external power if internal batteries are installed? What is the maximum cable length for real-time RS-232 data? Why do some instruments have zinc anodes, while others do not? Do Anti-Foulant Devices affect the conductivity cell calibration? What is Triton? Does it harm sensors? Do I need to purchase it from Sea-Bird? Where can I get information about safe handling/hazards associated with chemicals used with Sea-Bird equipment, such as Anti-Foulant Devices and Triton X-100 detergent? Why is Teflon tape used? My CTD has a Digiquartz pressure sensor. Can I use it above its rated pressure? My CTD has a Druck pressure sensor. Can I use it above its rated pressure? What do you recommend for cleaning barnacles off the exterior of the instrument? Why is the color on my instrument housing changing? Can I use hydrochloric acid to clean the outside of the housing? Why am I getting negative density values when testing the instrument? What is a wet-pluggable or wet-mateable or MCBH connector? Can I mate and unmate a cable with this connector underwater? Do you recommend a particular brand of alkaline D-cell batteries?
	General oceanographic questions What is the difference between psu and ppt? Is the salinity calculated by Sea-Bird valid above 42 psu? Does Sea-Bird software output Practical Salinity (psu) or Absolute Salinity? What is the difference between IPTS-68 and ITS-90? What is the difference between initial accuracy and resolution? Why is sound velocity (SV) computed from a CTD better than sound velocity from direct measuring instruments? Which algorithm for calculating sound velocity (SV) from CTD data should I use? What is hydrostatic head effect? How can I find the density of seawater at different temperatures and/or salinities? What is the cause of conductivity drift? Does it matter whether you use natural or artificial seawater for calibrations? Which does Sea-Bird use? Where can I purchase standard seawater? Why is my CTD data showing hysteresis?
	Recommended practices What are the major steps involved in taking a cast with a Profiling CTD? Should I collect water samples (close bottles) on the downcast or the upcast? Can I deploy my profiling CTD for monitoring an oil spill? What are the major steps involved in deploying a moored instrument? What are the recommended practices for mating and unmating connectors? How can I tell if my connectors have leaked, and what do I do about corrosion on connector pins? What are the recommended practices for replacing a bulkhead connector? What are the recommended practices for inspecting and cleaning o-rings and mating surfaces? How often should I replace o-rings? How should I handle my CTD to avoid cracking the conductivity cell? What is an Anti-Foulant Device? How often should I replace it? Does it require special handling? What are the recommended practices for deploying in frazil or pancake ice, or deploying at low temperatures? Does it matter if I deploy my moored instrument, which includes a conductivity sensor, in a horizontal or vertical position? How many / what kind of spares should I have on ship for my instrument? How many/what kind of spares should I have on ship for my SBE 9plus? How will my CTD be affected by adjacent objects? What are the safety concerns/procedures if the instrument floods? Can the instrument explode? Is it necessary to put my instrument in water to test it? Will I destroy the conductivity cell if I test it in air? How should I store my conductivity sensor if there is danger of freezing? What are the recommended practices for cleaning and lubricating winch cables? What are the recommended practices for splicing cables?
	Service How often do I need to have my instrument and/or auxiliary sensors recalibrated? Can I recalibrate them myself? I am planning to ship my instrument to Sea-Bird for calibration and minor repairs. What is the typical turn-around time? I am planning to ship my instrument to Sea-Bird for calibration and minor repairs. Should I also send the auxiliary sensors from other manufacturers? My auxiliary sensor (not manufactured by Sea-Bird) needs to be repaired / recalibrated. Where should I send it for servicing? I want to add an auxiliary sensor to my CTD. Assuming the auxiliary sensor is compatible with the instrument, what is the procedure? Do I need to remove batteries before shipping my instrument for a deployment or to Sea-Bird? Do I need to clean the exterior of my instrument before shipping it to Sea-Bird for calibration? 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? Can I brush clean and replatinize the conductivity cell myself? How often should this be done? 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? How can I tell if the conductivity cell on my CTD is broken? What are Configuration Sheets, and where can I find them for my instrument? What is Sea-Bird's policy on upgrading instruments? Should I purchase spare pressure sensors for my SBE 9plus? What do I need to send to Sea-Bird for calibration of my SBE 9plus? What do I need to send to Sea-Bird for calibration of my SBE 25 or 25plus? Does Sea-Bird have any calibration/service centers outside of the United States?
	Software I am confused by all these software names. Which software does what? Can I install my Sea-Bird CD-ROM on multiple computers or give it to another interested scientist? How can I copy the setup of my Sea-Bird software onto another computer? How can I view CTD data? What is a configuration (.con or .xmlcon) file and how is it used? What is a .psa file and how is it used? Does Seasoft have a provision for converting to MatLab data files? Can I use Seasoft on a Macintosh, Unix, or Linux system? Is the Windows version of Seasoft compatible with Microsoft's Vista operating system? Is the Windows version of Seasoft compatible with Microsoft's Windows 7 operating system? Your website Download Software from FTP Site page defines the latest software revision, but I cannot find the latest revision on the FTP site. Is it not posted yet? Why am I having trouble downloading software from your FTP site? How does Sea-Bird software calculate conductivity, temperature, and pressure in engineering units? How does Sea-Bird software calculate derived variables such as salinity, sound velocity, density, depth, thermosteric anomaly, specific volume, potential temperature, etc.? What is the flag variable column that is added to the data file by SBE Data Processing's Data Conversion or ASCII In module? What formula does Sea-Bird software use to convert pressure data to depth? In Sea-Bird software, is noon on January 1 Julian Day 0.5 or Julian Day 1.5? Can I edit my .dat data file to add some explanatory notes to header? Can I edit my .hex data file to add some explanatory notes to header? Why am I getting a class not registered error when running SBE Data Processing?
	Data analysis and processing Why and how should I align data from a 911plus CTD? What are the typical data processing steps recommended for each instrument? Where can I find formulas for calculating conductivity, temperature, pressure, and derived parameters such as salinity, sound velocity, density, depth, thermosteric anomaly, specific volume, potential temperature, etc.?
	Manufacturing Does Sea-Bird pressure test each instrument before shipping to verify integrity of housing, o-rings, assembly, etc.? Does Sea-Bird check and calibrate all sensors on a CTD system prior to shipping? Do Sea-Bird instruments have CE certification? Do Sea-Bird instruments have ISO certification?

Our Glossary page is another good source of information.

Product Configuration Options & Accessories lists all the features and options as well as accessories / spares for each product. Next to each product heading is a link for more details -- those pages provide explanatory information, illustrations, and photographs describing each item. Alternatively, you can navigate to the detailed pages from each product's specification sheet, by clicking on the Configuration link at the top of the specification sheet page.

Third Party Product Configuration Options lists instruments and integration options for sensors produced by other manufacturers (altimeters, fluorometers, transmissometers, etc.).

Sea-Bird does not publish prices on the website. Please contact us for pricing:

• Email seabird@seabird.com,
• Phone 425-643-9866,
• Fax 425-643-9954, or
• Fill out our Quote Request Form

Sea-Bird makes four main profiling CTD instruments, as well as several profiling CTD instruments for specialized applications.

In order of decreasing cost, the four main profiling CTD instruments are the SBE 911plus CTD, SBE 25plus Sealogger CTD, SBE 19plus SeaCAT Profiler CTD, and SBE 49 FastCAT CTD Sensor:

• The SBE 911plus is the world’s most accurate CTD. Used by most leading oceanographic institutions, the SBE 911plus is recognized for superior performance, reliability, and ease-of-use. Features include: modular conductivity and temperature sensors, Digiquartz pressure sensor, TC-Ducted Flow and pump-controlled time response, 24 Hz sampling, 8 A/D channels and power for auxiliary sensors, modem channel for real-time water sampler control without data interruption, and optional 9600 baud serial data uplink. The SBE 911plus system consists of: SBE 9plus Underwater Unit and SBE 11plus Deck Unit. The SBE 9plus can be used in self-contained mode when integrated with the optional SBE 17plus V2 Searam. The Searam provides battery power, internal 24 Hz data logging, and an auto-fire interface to an SBE 32 Carousel Water Sampler to trigger bottle closures at pre-programmed depths.
• The SBE 25plus Sealogger is the choice for research work from smaller vessel not equipped for real-time operation, or use by multi-discipline scientific groups requiring configuration flexibility and good accuracy and resolution on a smaller budget. The SBE 25plus is a battery-powered, internally-recording CTD featuring the same modular C & T sensors used on the SBE 9plus CTD, an integral strain gauge pressure sensor, 16 Hz sampling, 2 GB of memory, TC-Ducted Flow and pump-controlled time response, and 8 A/D channels plus 2 RS-232 channels and power for auxiliary sensors. Real-time data can be transmitted via RS-232 simultaneous with data recording. The SBE 25plus integrates easily with an SBE 32 Carousel Water Sampler or SBE 55 ECO Water Sampler for real-time or autonomous operation.
• The SBE 19plus V2 SeaCAT Profiler is known throughout the world for good performance, reliability, and ease-of-use. An economical, battery-powered, internally-recording mini-CTD, the SBE 19plus V2 is a good choice for basic hydrography, fisheries research, environmental monitoring, and sound velocity profiling. Features include 4 Hz sampling, 6 differential A/D channels plus 1 RS-232 channel and power for auxiliary sensors, 64 MB of memory, and pump-controlled conductivity time response. Real-time data can be transmitted via RS-232 simultaneous with data recording, The SBE 19plus V2 integrates easily with an SBE 32 Carousel Water Sampler or SBE 55 ECO Water Sampler for real-time or autonomous operation.
• The SBE 49 FastCAT is an integrated CTD sensor intended for towed vehicle, ROV, AUV, or other autonomous profiling applications. Real-time data ‑ in raw format or in engineering units ‑ is logged or telemetered by the vehicle to which it is mounted. The SBE 49’s pump-controlled, TC-ducted flow minimizes salinity spiking, and its 16 Hz sampling provides very high spatial resolution of oceanographic structures and gradients. The SBE 49 has no memory or internal batteries. The SBE 49 integrates easily with an SBE 32 Carousel Water Sampler or SBE 55 ECO Water Sampler for real-time operation.

The specialized profiling CTD instruments are the SBE 52-MP Moored Profiler, Glider Payload CTD, and SBE 41/41CP Argo CTD module:

• The SBE 52-MP Moored Profiler is a conductivity, temperature, pressure sensor, designed for moored profiling applications in which the instrument makes vertical profile measurements from a device that travels vertically beneath a buoy, or from a buoyant sub-surface sensor package that is winched up and down from a bottom-mounted platform. The 52-MP's pump-controlled, TC-ducted flow minimizes salinity spiking. The 52-MP can optionally be configured with an SBE 43F dissolved oxygen sensor.
• The Glider Payload CTD measures conductivity, temperature, and pressure, and optionally, dissolved oxygen (with the modular SBE 43F DO sensor). It is a modular, low-power profiling instrument for autonomous gliders with the high accuracy necessary for research, inter-comparison with moored observatory sensors, updating circulation models, and leveraging data collection opportunities from operational vehicle missions. The pressure-proof module allows glider users to exchange CTDs (and DO sensors) in the field without opening the glider pressure hull.
• Argo floats are neutrally buoyant at depth, where they are carried by currents until periodically increasing their displacement and slowing rising to the surface. The SBE 41/41CP CTD Module obtains the latest CTD profile each time the Argo float surfaces. At the surface, the float transmits in-situ measurements and drift track data to the ARGOS satellite system. The SBE 41/41CP can be integrated with Sea-Bird's Navis float, Navis float with Biogeochemical Sensors, or floats from other manufacturers. The SBE 41N CTD is integrated with Sea-Bird's Navis Float with Integrated Biogeochemical Sensors.

See Products at a Glance for a table summarizing the features of our profiling CTDs.

Sea-Bird currently manufactures only 1 moored CTD that can accept auxiliary sensors, the SBE 16plus V2 SeaCAT (and its inductive modem version, the 16plus-IM V2). These instruments measure conductivity and temperature; a pressure sensor is optional. They have 6 differential A/D channels and 1 RS-232 channel available for auxiliary sensors.

Notes:

• The SBE 19plus V2 SeaCAT, intended primarily for profiling applications, can also be used in moored mode. The 19plus V2 also has 6 differential A/D channels and 1 RS-232 channel available for auxiliary sensors. When in moored mode, it functions similar to a 16plus V2 with optional pressure sensor.
• The older versions of these products, the SBE 16 / 16plus and SBE 19 / 19plus, also accept auxiliary sensors.

See Products at a Glance for a table summarizing the features of our moored instruments.

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

This depends on your own expertise and resources. We have extensive experience in integrating and supporting a wide range of auxiliary sensors, but not everything under the sun. We have a large list of commonly used sensors that we routinely offer for sale (see our Third Party Product Configuration page).

When you purchase any of these auxiliary sensors from Sea-Bird, we are able to apply this experience to integrating the sensors with the CTD. The integration includes installing the sensors (with appropriate mounting kits and cables) in a manner that puts each sensor in the best possible orientation for optimum performance. It also includes configuring the CTD system and software to accept the sensors’ inputs and properly display the data, and testing the entire system, typically in a chilled saltwater bath overnight, to confirm proper operation. Having done the integration, we also support the entire system in terms of follow-on service and end-user support with operational and data analysis questions *. There is significant added value in our integration service, and there is some extra cost for this, compared to doing it yourself. However, we do not base our business on selling services, and the prices charged for Third Party sensors carry minimal mark-ups that vary depending on the pricing we are offered by the manufacturers. In some cases we can sell at the manufacturer's list price, and in others we have to add margin.

*Notes:
1. As described in our Warranty Policy, auxiliary sensors manufactured by other companies are warranted only to the limit of the warranties provided by their original manufacturers (typically 1 year).
2. See FAQs -- Service for information on repairing / recalibrating auxiliary sensors manufactured by other companies.

Wet-pluggable (also referred to as wet-mateable or MCBH) connectors, an option on all of our underwater instruments, may be mated in wet conditions. Their pins do not need to be dried before mating. By design, water on the connector pins is forced out as the connector is mated. However, they must not be mated or un-mated while submerged. Wet-pluggable connectors have a non-conducting guide pin to assist pin alignment & require less force to mate, making them easier to mate reliably under dark or cold conditions, compared to our Impulse XSG/RMG connectors (XSG/RMG connectors may not seal well in extreme cold; we recommend connecting cables in warm ship’s lab rather than on deck for these conditions). Like XSG/RMG connectors, wet-pluggables need proper lubrication & require care during use to avoid trapping water in sockets.

Note: Prior to 2005, the wet-pluggable connectors available had a rubber-to-metal seal that could break down with prolonged use (3 - 5 years); seal breakdown will lead to instrument flooding. Sea-Bird recommended frequent inspection of the connectors for damage. We also discouraged the use of wet-pluggable connectors for moored deployments, because they cannot be inspected during a prolonged deployment.
From 2005 to 2007, Sea-Bird transitioned to the WB (water block) type of wet-pluggable connectors. WB connectors have a water block that minimizes the possibility of instrument flooding; we do not discourage the use of these types of connectors for moored deployments. If you have wet-pluggable connectors on your instrument and are unsure of which type you have, contact Sea-Bird.

For a Sea-Bird CTD used with one of our Deck Units (SBE 11plus, SBE 33, or SBE 36), the electrical requirements of the armored cable are simple. Only one conductor is required (the armor is used as ground) and the total 2-way resistance (conductor plus armor) should be under 350 ohms. The mechanical requirements are most driven by the characteristics of the winch and weight of the payload to be lifted. The winch should have a level wind device which is either adjustable or pre-designed to lay the correct number of wraps across the drum, as determined by the cable diameter and drum width. The winch must also be equipped with a slip ring (rotating contact) assembly (at least 2 channels). A cable breaking strength of at least 5 to 7 times the maximum payload weight is recommended for safety and cable longevity. The cable must also be terminated both mechanically and electrically at the underwater (instrument) end. Cable termination (mechanical) at the winch drum is usually addressed by the winch maker. The cable is terminated electrically to the slip ring per the slip ring manufacturer's specification.

Sea-Bird is not expert in winch and deck gear and cannot recommend a block and A-frame. From past experience and with knowledge of what other customers use, we can point out sources for typical cable solutions, and cable terminations suppliers. For links to suppliers of winches, cable, and cable termination hardware, see our Cable and Winch Manufacturers page.

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