Specifications

1
APPLICATION NOTE NO. 2D Revised October 2006
Instructions for Care and Cleaning of Conductivity Cells
This application note presents new recommendations, based on our recent research, for cleaning and storing
conductivity sensors. In the past, Sea-Bird had recommended cleaning and storing conductivity sensors with a Triton
X-100 solution, and cleaning conductivity sensors with an acid solution. Our latest research leads us to recommend
adding the use of a dilute bleach solution to eliminate growth of bio-organisms, and eliminating the use of acid in
most cases.
The application note is divided into three sections:
General discussion
Rinsing, cleaning, and storage procedures
Cleaning materials
General Discussion
Since any conductivity sensors output reading is proportional to its cell dimensions, it is important to keep the cell
clean of internal coatings. Also, cell electrodes contaminated with oil, biological growths, or other foreign material will
cause low conductivity readings. A desire to provide better control of growth of bio-organisms in the conductivity cell
led us to develop revised rinsing and cleaning recommendations.
A dilute bleach solution is extremely effective in controlling the growth of bio-organisms in the conductivity
cell. Lab testing at Sea-Bird over the past year indicates no damaging effect from use of a dilute bleach
solution in cleaning the conductivity cell. Sea-Bird now recommends cleaning the conductivity sensor in a
bleach solution.
Triton X-100 is a mild, non-ionic surfactant (detergent), valuable for removal of surface and airborne oil
ingested into the CTD plumbing as the CTD is removed from the water and brought on deck. Sea-Bird had
previously recommended, and continues to recommend, rinsing and cleaning the conductivity sensor in a
Triton solution.
Sea-Bird had previously recommended acid cleaning for eliminating bio-organisms or mineral deposits on
the inside of the cell. However, bleach cleaning has proven to be effective in eliminating growth of bio-
organisms; bleach is much easier to use and to dispose of than acid. Furthermore, data from many years of
use shows that mineral deposits are an unusual occurrence. Therefore, Sea-Bird now recommends that, in
most cases, acid should not be used to clean the conductivity sensor. In rare instances, acid cleaning may
still be required for mineral contamination of the conductivity cell. Sea-Bird recommends that you return
the equipment to the factory for this cleaning if it is necessary.
Sea-Bird had previously recommended storing the conductivity cell filled with water to keep the cell wetted, unless the
cell was in an environment where freezing is a possibility (the cell could break if the water freezes). However, no
adverse affects have been observed as a result of dry storage, if the cell is rinsed with fresh, clean water before storage
to remove any salt crystals. This leads to the following revised conductivity cell storage recommendations:
Short term storage (less than 1 day, typically between casts): If there is no danger of freezing, store the
conductivity cell with a dilute bleach solution in Tygon tubing looped around the cell. If there is danger of
freezing, store the conductivity cell dry, with Tygon tubing looped around the cell.
Long term storage (longer than 1 day): Since conditions of transport and long term storage are not always under
the control of the user, we now recommend storing the conductivity cell dry, with Tygon tubing looped around the
cell ends. Dry storage eliminates the possibility of damage due to unforeseen freezing, as well as the possibility of
bio-organism growth inside the cell. Filling the cell with a Triton X-100 solution for 1 hour before deployment will
rewet the cell adequately.
Note that the Tygon tubing looped around the ends of the conductivity cell, whether dry or filled with a bleach or Triton
solution, has the added benefit of keeping air-borne contaminants (abundant on most ships) from entering the cell.
Sea-Bird Electronics, Inc.
1808 136th Place NE
Bellevue, WA 98005
US
A
Phone: [phone]
Fax: [phone]
E-mail: [e-mail]
Web: www.seabird.com
