YSI 6 series User Manual page 356

ROX Optical DO Sensor
How should I store my ROX sensor when it is not in use?
When the 6150 sensor is not in field use, it MUST BE STORED IN A MOIST ENVIRONMENT, i.e.,
either in water or in water-saturated air with storage in water being preferable. If the sensor membrane is
allowed to dry out by exposure to ambient air, it is likely to drift slightly at the beginning of your next
deployment unless it is rehydrated. Thus, to make the use of the sensor as simple as possible, remember to
store it WET whenever possible. 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.
If I have inadvertently allowed my ROX sensor membrane to dry out for several days, is it ruined?
No. The sensor membrane can easily be rehydrated using the following basic procedure:
Place approximately 400 mL of water in a 600 mL beaker or other similar glass vessel – do NOT
use plastic vessels – and heat the water on a thermostatted hotplate or in an oven so that a
consistent temperature of 50+/- 5 C is realized. Place the probe tip containing the sensor
membrane in the warm water and leave it at the elevated temperature for approximately 24 hours.
Cover the vessel if possible to minimize evaporation. After rehydration is complete, store the
probe in either water or water-saturated air prior to calibration and deployment.
Once the rehydration has been performed, the sensor should be returned to its original performance
specification.
Can I use alcohol or other organic solvents to clean my sensor membrane?
Absolutely NOT. Alcohol will dissolve the outer paint layer of the membrane assembly and other organic
solvents will likely dissolve the dye itself. Under NO circumstances should you use organic solvents to
clean your sensor membrane. The best method of cleaning the membrane is just to gently wipe away any
fouling with a piece of lens cleaning tissue which has been moistened with water only.
I have a few pinholes in the outer paint layer of my sensor membrane so that I can see small spots of
light from the probe. Will this light leakage affect the performance of my ROX sensor?
No. A few small pinholes in the outer paint layer will have no discernable effect on sensor performance.
However, if there are a lot of holes or if they are relatively large (1 mm or greater in diameter), then there
might be a minor compromise of sensor accuracy relative to the factory calibration. Under these latter
conditions, YSI would recommend replacing the membrane assembly.
Is there any effect of ambient light on the readings from the ROX DO sensor?
Under all normal operating conditions, the ROX sensor is unaffected by ambient light, even if there are a
few minor scrapes or pinholes in the protective paint layer of the sensor membrane. These conditions
include exposure to room lighting during calibration and set-up and deployments in all clarities of water as
long as the ROX sensor is pointed down or on its side. Our studies indicate that only if the ROX sensor is
exposed directly to bright sunlight with the probe pointed upward will the readings be affected
significantly. Thus, there is no reason to worry about the effect of ambient light unless your deployment
sight is very unusual and requires that the sensor be pointed directly upward in shallow water with no probe
YSI Incorporated Environmental Monitoring Systems Operations Manual
Appendix M
M-
7