YSI Pro-BOD - Manual (Page 9)

7
O
PERATING
P
ROCEDURES AND
P
RECAUTIONS
---IMPORTANT---
Intended Use
The 5905/5010/200-BOD/Pro-BOD probe is intended for
laboratory use, not field use. It is not waterproof and should
never be immersed past the taper on the stem of the probe.
Air Calibration
When calibrating in air, make sure there are no water droplets on
the membrane. Water droplets will cause a low calibration
reading. Excess water may be removed by shaking the probe
downward. If droplets persist it may be necessary to carefully
remove them using a clean cloth or paper towel.
Checking the Probe Zero
The probe zero is checked by immersing the probe in a sodium
sulfite solution (0.08M or 3g Na
2
SO
3
/300mL), or in water which
has an inert gas bubbling through it (e.g. nitrogen, argon). The
meter should read less than 1% dissolved oxygen in either of
these environments. If it does not, change the membrane or clean
the probe.
Membrane Life
Membrane life depends on use. Membranes will last longer if
installed properly and treated with care during use. Erratic
readings will result from loose, wrinkled, or fouled membranes or
from bubbles larger than 1/8” in the electrolyte solution. If erratic
readings or other evidence of membrane damage occurs, replace
the membrane and KCl solution.