• Preventive Field Maintenance Between Profiles: After each cast, flush with a 0.1% solution of Triton X-100,
using a 60 cc syringe (see Application Note 34). Then rinse thoroughly with fresh water. Between casts, ensure
that the sensor remains shaded from direct sunlight and stays cool and humidified. Plugging the inlet and exhaust
of the plumbing after rinsing will trap sufficient humidity.
• Routine (post-cruise) Cleaning (no visible deposits or marine growths on sensor) - Follow this
two-step procedure:
A. Flush the sensor for 1 minute with a 1% solution of Triton X-100 warmed to 30 ºC (86 ºF).
Drain and flush with warm (not hot) fresh water for 5 minutes.
B. Soak the sensor for 1 minute in a 500 – 1000 ppm solution of Bleach. After the soak, drain and flush
with lukewarm (not hot) fresh water for 5 minutes.
• Cleaning Severely Fouled Sensors (visible deposits or marine growths on sensor): Soak the sensor in
de-ionized water overnight to loosen deposits. Repeat the Routine Cleaning procedure up to 5 times.
Do not attempt to clean the membrane with high pressure flow or by wiping or touching the membrane.
• Long-Term Storage (after field use): Do not fill the tubing with water, Triton solution, or Bleach solution.
¾ If there is no danger of freezing, loop tubing from inlet to outlet. Place a small piece of clean sponge,
slightly dampened with fresh, clean water, in the center of the tubing (not near the membrane).
¾ If there is danger of freezing, shake all excess water out of the plenum and loop tubing from inlet to
outlet, leaving the sensor membrane dry.
¾ Because the sensor is continuously polarized by an internal battery, oxygen in the plenum and tubing will
continue to be consumed, depleting the electrolyte and causing drift. Storing the sensor in a zero-oxygen
environment will stop calibration drift between uses. To minimize drift during storage, if possible, connect
one end of the tubing loop to the plenum, displace the air in the plenum and tubing with Nitrogen gas, and
connect the other end of the tubing to the plenum. If tubing is not available, displace the air in the plenum
with Nitrogen gas and close off the plenum with a cap on each end (tape can be used if nothing else is
available); do not insert a cap or plug inside the plenum.
Materials
• Triton X-100 - 100% Triton X-100 is included with every CTD shipment and may be ordered from Sea-Bird;
dilute as directed above. Triton X-100 is Octyl Phenol Ethoxylate, a mild, non-ionic surfactant (detergent), and is
manufactured by Mallinckrodt Baker (see http://www.mallbaker.com/changecountry.asp?back=/Default.asp
for local distributors). Other liquid detergents can probably be used, but scientific grades having no colors,
perfumes, glycerins, lotions, etc. are required.
• Bleach – Bleach is a common household product used to whiten and disinfect laundry. Commercially available
bleach is typically 4% - 7% (40,000 ppm – 70,000 ppm) sodium hypochlorite (Na-O-Cl) solution that includes
stabilizers. Some common commercial product names are Clorox (U.S.) and eau de Javel (French).
Clean the SBE 43 with a 500 – 1000 ppm solution of water and sodium hypochlorite. Dilute the concentrated
household bleach 50 to 1 (50 parts water to 1 part bleach) to produce the proper concentration to clean the
oxygen sensor.
• Water – We recommend de-ionized (DI) water because it is reliably pure, but commercially distilled water or
fresh clean tap water is also sufficient for all uses above. On ships, fresh water can occasionally contain traces
of oil and should not be used for rinsing, cleaning, or storing sensors, unless there is no alternative.
Notes:
• Do not use stronger solutions or longer wash times than recommended above.
• Do not place concentrated Triton or bleach directly on the SBE 43 sensor membrane. A strong Triton solution
can leave a film on the membrane, adversely affecting results.
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