Xylem 6-Series Multiparameter - Manual (Page 128)

Sondes Section 2
YSI Incorporated Environmental Monitoring Systems Operations Manual 2-122
RAPID PULSE DISSOLVED OXYGEN
Rapid Pulse dissolved oxygen sensors should always be stored with a membrane and electrolyte in place
and in such a way that the drying out of the electrolyte on the probe face is minimized. For long-term
storage, the medium should be water rather than the moist air used in interim storage. The long-term
storage protocol is also dependent on the instrument under consideration.
ROX dissolved oxygen sensors should always be stored in a moist environment, i.e., either in water or in
water-saturated air with storage in water being preferable. The easiest storage method is to use the
protective plastic cap (and enclosed sponge) which was on the probe at receipt. If you have retained this
cap/sponge, then simply soak the sponge in water and replace the cap on the probe tip. Inspect the sponge
every 30 days to make sure it is still moist. Alternatively, you can remove the probe from the sonde and
place it directly in water (making sure that the water does not evaporate over time or leave the probe in the
sonde and make certain that the calibration cup has an atmosphere which is water-saturated by placing
approximately ½ inch of water in the bottom of the cup and then sealing it snugly to the sonde.
For all 6-series sondes other than the 600R, 600QS, and 600 OMS V2-1, two long-term storage methods
are equally acceptable.
1. Remove all probes other than dissolved oxygen (Rapid Pulse or ROX), conductivity, and
temperature from the sonde and seal the vacant ports with the provided port plugs. Leave the
electrolyte and membrane in place on the Rapid Pulse dissolved oxygen sensor. Fill the
calibration cup with water (tap, deionized, or distilled are equally acceptable) and insert the sonde.
Make certain the water level is high enough to completely cover the DO sensor. Seal the vessel to
prevent evaporation of the water. At the end of the storage time, remove the existing membrane
and re-membrane the probe using new electrolyte.
2. Remove the Rapid Pulse dissolved oxygen sensor from the sonde leaving the electrolyte and
membrane in place. Store the probes in water (tap, deionized, or distilled are equally acceptable)
in a beaker, flask, or other vessel of the user‟s choice. Be sure not to damage the membrane or
the probe tip when placing the probe on the bottom of the vessel. If possible cover the vessel
with parafilm or plastic wrap to minimize evaporation of the water during long-term storage.
Monitor the water level in the storage vessel periodically and replenish if loss due to evaporation
occurs. At the end of the storage time, remove the existing membrane and re-membrane the probe
using new electrolyte.
Because the user cannot remove the dissolved oxygen probe of the 600R and 600QS from the sonde, a
slightly different long-term storage protocol is required:
For 600 systems equipped with a replaceable reference electrode module, remove the reference module,
store it as described below and plug the open port with the port plug that was provided. Make certain that
the dissolved oxygen sensor has an undamaged membrane and electrolyte in place. Fill the provided
storage vessel with a solution which is 2 molar (2 M) in potassium chloride (KCl), insert the sonde and seal
the vessel with the cap and O-ring. This solution can be prepared by dissolving 74.6 g of KCl in 500 mL
(approximately 1 pint) of water or 37.3 g of KCl in 250 mL (approximately 0.5 pint) of water. The water
should be distilled or deionized. If KCl solution is unavailable, it is acceptable to store the dissolved
oxygen and pH glass sensors in tap water. Do not use deionized or distilled water in this case, as it may
damage the pH glass sensor, which must remain in the sonde. At the end of the storage time, remove
the existing membrane and re-membrane the probe using new electrolyte.