Frequently Asked Questions (FAQs) --
General Instrument Questions
FAQs have been organized into the following categories:
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General instrument questions (this page) |
- How do instruments that can be internally or externally powered handle external power if internal batteries are installed?
- 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?
- 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?
Our Glossary page is another good source of information.
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.
A zinc anode attracts corrosion and prevents aluminum from corroding until all the zinc is eaten up. Sea-Bird uses zinc anodes on an instrument if it has an aluminum housing and/or end cap. Instruments with titanium or plastic housings and end caps (for example, SBE 37 MicroCAT) do not require a sacrificial anode.
Anti-Foulant Devices have no effect on the calibration, because they do not affect the geometry of the 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.
Triton X-100 is Octyl Phenol Ethoxylate, a reagent grade non-ionic surfactant (detergent). Sea-Bird uses it to help keep our conductivity cells clean and the electrodes wetted and ready for immediate use in water (a dry cell requires a few minutes to become completely wetted after immersion). Triton X-100 will not harm conductivity cells, temperature sensors, or pumped fluorometers. Do not place concentrated Triton X-100 directly on the membrane of a dissolved oxygen sensor.
Triton X-100 is supplied in 100% strength.
Conductivity sensors -- Triton is typically diluted to 0.1% strength (by 1000) for rinsing and for rewetting the conductivity cell just before deployment, and to 1% to 2% strength (by 50 to 100) for cleaning the conductivity cell. Refer to Application Note 2D: Instructions for Care and Cleaning of Conductivity Cells and to the maintenance section in the instrument manual for details.
Dissolved Oxygen sensors -- Triton is typically diluted to 0.1% strength (by 1000) for rinsing, and to 1% (by 100) for cleaning. Refer to Application Note 64: SBE 43 Dissolved Oxygen Sensor for details.
Triton X-100 can be ordered from Sea-Bird, but should also be available locally from a chemical supply or laboratory products companies. It is manufactured by Mallinckrodt Baker (see http://www.mallbaker.com/changecountry.asp?back=/Default.asp for local distributors). See our MSDS page to view the Material Safety Data Sheet.
See Material Safety Data Sheets (MSDS) for chemicals commonly used with Sea-Bird instruments.
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.
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.
The overpressure rating for a 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.
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. After scraping off the barnacles and marine growth, rinse the instrument well with fresh water.
Note: If sending the instrument to Sea-Bird for calibration, remove as much biological material as possible before shipping. Sea-Bird cannot place an instrument with a large amount of biological material on the housing in our calibration bath; if we need to clean the exterior before calibration, we will charge you for this service.
The housings of some of our instrument are made from anodized aluminum. In our experience it is very common to see color change when anodized housings are moored in seawater. We even see some discoloration during the brief time instruments undergo calibration and testing.
There are probably several causes of discoloration:
Zinc from the protective anodes tends to deposit on the surface, causing the color to lighten toward gray.
Some seawater components, for example, carbonates, may precipitate onto the surfaces.
The anodized coating does not completely cover the aluminum: at microscopic scale the coating has the appearance of a dry lake bed ‑ there are patches of anodizing surrounded by cracks. These cracks allow water to reach bare aluminum and cause local oxidation that is light in color. Fortunately, once a thin oxide coating forms on aluminum, further corrosion tends to be inhibited. Unless you see severe pitting, there is usually no danger to the safety of the housing.
We do not advise using hydrochloric acid (HCl) to clean instrument housings. Such highly corrosive acids will not hurt the anodized surfaces, but will attack any bare aluminum ‑ including the aluminum in the cracks ‑ and can also damage O-rings, connectors, and other sensor components. A milder acid, for example household (cooking) vinegar, is a better choice.
Several customers who have completely wrapped their instrument housings with plastic tape report good results. The bio-organisms still grow, but after recovery it is easy to peel off the tape, shells and mussels and all!
The density equation is not valid for a salinity less than 2 psu, so if you test your instrument in fresh water your data will show negative density. For more information on the practical salinity scale, refer to UNESCO Technical Papers of Marine Science 44.
Wet-pluggable (also referred to as wet-mateable or MCBH) connectors, an option on many of our 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 and require less force to mate, making them easier to mate reliably under dark or cold conditions, compared to our standard (Impulse XSG/RMG) connectors (standard 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 standard connectors, wet-pluggables need proper lubrication and require care during use to avoid trapping water in sockets.
Last modified: 06 Apr 2007
Sea-Bird Home Phone: 425-643-9866 Fax: 425-643-9954 E-mail: seabird@seabird.com
