Specifications

4
Acid
In rare instances, acid cleaning is required for mineral contamination of the conductivity cell. Sea-Bird
recommends that you return the equipment to the factory for this cleaning. Information below is provided if you
cannot return the equipment to Sea-Bird.
CAUTIONS:
SBE 37-IMP, 37-SMP, or 37-SIP MicroCAT; SBE 49 FastCAT; or other instruments with an integral,
internal pump - Do not perform acid cleaning. Acid cleaning may damage the internal, integral pump.
Return these instruments to Sea-Bird for servicing if acid cleaning is required.
SBE 9plus or SBE 25 CTD  Remove the SBE 4 conductivity cell from the CTD and remove the TC Duct
before performing the acid cleaning procedure.
All instruments which include AF24173 Anti-Foulant Devices  Remove the AF24173 Anti-Foulant
Devices before performing the acid cleaning procedure. See the instrument manual for details and handling
precautions when removing AF24173 Anti-Foulant Devices.
WARNING! Observe all precautions for working with strong acid. Avoid breathing acid fumes. Work in
a well-ventilated area.
The acid cleaning procedure for the conductivity cell uses approximately 50 - 100 cc of acid. Sea-Bird recommends
using a 20% concentration of HCl. However, acid in the range of 10% to full strength (38%) is acceptable.
If starting with a strong concentration of HCl that you want to dilute:
For each 100 cc of concentrated acid, to get a 20% solution, mix with this amount of water -
Water = [(conc% / 20%)  1 ] * [100 + 10 (conc% / 20% )] cc
Always add acid to water; never add water to acid.
Example -- concentrated solution 31.5% that you want to dilute to 20%:
[(31.5% / 20%)  1 ] * [100 + 10 (31.5% / 20% )] = 66.6 cc of water.
So, adding 100 cc of 31.5% HCl to 66.6 cc of water provides 166.6 cc of the desired concentration.
For 100 cc of solution:
100 cc * (100 / 166.6) = 60 cc of 31.5% HCl 66.6 cc * (100 / 166.6) = 40 cc of water
For acid disposal, dilute the acid heavily or neutralize with bicarbonate of soda (baking soda).
1. Prepare for cleaning:
A. Place a 0.6 m (2 ft) length of Tygon tubing over the end of the cell.
B. Clamp the instrument so that the cell is vertical, with the Tygon tubing at the bottom end.
C. Loop the Tygon tubing into a U shape, and tape the open end of the tubing in place at the same height
as the top of the glass cell.
2. Clean the cell:
A. Pour 10% to 38% HCl solution into the open end of the tubing until the cell is nearly filled. Let it
soak for 1 minute only.
B. Drain the acid from the cell and flush for 5 minutes with warm (not hot), clean, de-ionized water.
C. Rinse the exterior of the instrument to remove any spilled acid from the surface.
D. Fill the cell with a 1% Triton X-100 solution and let it stand for 5 minutes.
E. Drain and flush with warm, clean, de-ionized water for 1 minute.
F. Carefully remove the 0.6 m (2 ft) length of Tygon tubing.
3. Prepare for deployment, or follow recommendations above for storage.
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