YSI YSI 5905 User manual

YSI 5905/5010
BOD Probe
Instruction
Manual

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Table of Contents
INTRODUCTION........................................................................ 1
OPERATING PRINCIPALS......................................................... 2
USING THE 5905/5010 BOD PROBE....................................... 3
CHANGING MEMBRANE CAPS - FIGURE 2 ............................ 3
WARM UP............................................................................ 5
ELECTRODE CLEANING - FIGURE 3....................................... 5
OPERATING PROCEDURES AND PRECAUTIONS....................... 7
PROBLEM SOLVING................................................................. 9
TROUBLE SHOOTING GUIDE ................................................. 9
SERVICING............................................................................. 11
WARRANTY AND REPAIR ...................................................... 13
CLEANING INSTRUCTIONS .................................................. 15
PACKING INSTRUCTIONS..................................................... 16
PROBE SPECIFICATIONS........................................................ 18
APPENDIX A........................................................................... 19
APPENDIX B........................................................................... 20

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1
INTRODUCTION
The YSI Model 5905/5010 BOD (Biochemical Oxygen
Demand) probe is used for measuring dissolved oxygen in all
popular size BOD bottles. This probe features self stirring, an
easily replaced membrane cap, and a refurbishable electrode
system.
The 5905 probe is designed for use with all YSI dissolved
oxygen meters, except for the Model 55 or Model 95. It must
be used with an adapter (5011) in order to be used on the
Model 5000 and 5100.
The 5010 probe is specifically designed for use with the Model
5000 and 5100 only.
This manual also applies to probes 5905-J, 5905-K, 5905-L,
5905-W (Appendix A), and probes 5010-J, 5010-K, 5010-L,
and 5010-W (Appendix A)
IMPORTANT
Intended Use
The 5905/5010 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.

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OPERATING PRINCIPALS
The 5905/5010 BOD probe is a voltammetric (polarographic)
sensor of dissolved oxygen. An oxygen permeable membrane
covers an electrolytic cell consisting of a cathode and an
anode. This membrane acts as a diffusion barrier and an
isolation barrier preventing the fouling of the cathode surface
by impurities in the environment. The cathode is the gold
electrode, and the anode is the silver electrode which
completes the electrolytic cell and acts as a reference
electrode.
Upon entering the cell through the membrane, oxygen is
reduced at an applied potential of -0.8 V referenced to the
silver electrode. The reduction current at the cathode is
directly proportional to the partial pressure of oxygen in liquid
(expressed as %-air saturation) which is also proportional to
the concentration of dissolved oxygen (in mg/L) at a particular
temperature. Thus the same partial pressure of oxygen (%-air
saturation) in liquid gives different concentrations of dissolved
oxygen (mg/L) at different temperatures because of the
different solubilities of oxygen at different temperatures.

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USING THE 5905/5010 BOD PROBE
Note: The 5905 must be plugged into a YSI meter and the
stirrer power plug must be plugged into its power adapter. The
5010 must be plugged into a YSI meter only, as it gets its
stirring power from the 5000/5100 instrument.
CHANGING MEMBRANE CAPS - FIGURE 2
Follow these instructions to change membrane caps:
1. Remove the stir paddle from the probe by pulling it straight
out.
2. Unscrew the old membrane cap from the probe. Before
installing a new membrane, clean the probe tip with
deionized water in order to remove any contaminants.
3. Hold the membrane cap and fill it at least ½ full with the
electrolyte solution provided. Screw the membrane cap onto
the probe moderately tight. A small amount of electrolyte
should overflow.
4. Rinse off excess electrolyte from the probe with deionized
water.
5. Reinstall the stir paddle.
New Probe Use
New probes are shipped with a dry membrane cap to protect
the electrodes. A new membrane cap must be installed
before first use.

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Fill Membrane Cap
with Solution
Unscrew Cap
Remove
Stir Paddle
Screw Cap on
moderately tight
Replace
Stir Paddle
Figure 2 Membrane Installation on the 5905/5010 Probe.

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WARM UP
Every time the meter is turned on, the 5905/5010 BOD Probe
must be allowed to warm up for about 30 minutes before
taking the first reading. This allows the probe to use up all the
oxygen retained in the cap.
New Probe Break In (Motor Off)
ELECTRODE CLEANING - FIGURE 3
The 5905/5010 should be cleaned only when erratic readings
occur or after about every 500 hours of use (two months).
Each cleaning removes material and reduces the life of the
probe, so excessive cleaning should be avoided.
Gold Cathode:
For correct probe operation, the gold cathode must be textured
properly. It can become tarnished or plated with silver after
extended use. The gold cathode can be cleaned by using the
adhesive backed sanding disc provided in the 5906 Membrane
Kit. Stick the disc to a small flat object, like a bottle cap, then
sand the gold with a twisting motion about 3 times or until all
silver deposits are removed and the gold appears to have a
For best results, please allow the probe more than the usual 30
minutes to warm-up after the first membrane is installed. The
process may be faster if the probe is allowed to warm up in a
BOD bottle filled with clean water. If possible, it’s a good idea
to let new probes warm-up over night (with a new membrane
and KCl) prior to their first use.

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matte finish. If the cathode remains tarnished, return the probe
for service.
Cathode
(Gold)
Temperature
Sensor
Anode
(Silver)
Figure 3 5905/5010 Sensor
Silver Anode:
It is normal for a dark layer of silver chloride to cover the
silver anode. After prolonged use it may become necessary to
clean the anode. Soak the probe in a 14% ammonium
hydroxide solution for 2 to 3 minutes or overnight in a 3%
ammonium hydroxide solution. Rinse with deionized water,
recharge with electrolyte, and install a new membrane.

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OPERATING PROCEDURES AND PRECAUTIONS
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 Na2SO3/300mL), 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. The
IMPORTANT
Intended Use
The 5905/5010 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.

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average replacement interval is one to two weeks. Probes in
constant or heavy use may require more frequent membrane
changes.
Interferences
Hydrogen sulfide, sulfur dioxide, halogens, carbon monoxide,
chlorine, nitric oxide, and nitrous oxide can cause the probe to
give erroneous readings. If you suspect erroneous readings, it
may be necessary to determine if these are the cause.
Acids
Avoid any environment that contains substances such as
concentrated acids, caustics, and strong solvents that may
attack the probe. Probe materials that may be damaged by
these substances include FEP Teflon, EPR rubber, ABS
plastic, and stainless steel.
Erroneous Readings
Erroneous readings may occur if the membrane is coated with
oxygen consuming bacteria or oxygen evolving algae. Heavy
residue may coat the membrane causing incorrect readings.
Frequent membrane changes will eliminate this problem.
Storage
When the probe is not in use, store the probe in a BOD bottle
containing at least 1 inch of water. For long term storage,
remove the membrane cap, rinse the probe tip with deionized
water, and install a dry membrane cap (without electrolyte
solution).

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PROBLEM SOLVING
TROUBLE SHOOTING GUIDE
Below is a quick reference of symptoms with steps to follow
to cure these symptoms.
Symptoms Actions
Unable to
calibrate •Allow approximately 30
min. for probe to polarize
when first turned on
•Change membrane
•Clean probe (see
instructions under
Electrode Cleaning)
Does not return
to calibration
value
•Allow sufficient time for
temperature and oxygen
stabilization
•Check for water droplets on
membrane
•Change membrane
•Clean probe (see
instructions under
Electrode Cleaning)

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Symptoms Actions
Unstable
readings •Allow sufficient time for
temperature and oxygen
stabilization
•Allow 60 sec for reading to
stabilize
•Change membrane
•Clean probe (see
instructions under
Electrode Cleaning)
Motor not
working •Check power supply
•Manually turn the stir
paddle to help start the
motor
•Replace motor
Loud motor •Check if stir paddle is
pushed all the way in
•Replace motor
Membrane cap is
tight •Use pliers to loosen the cap
(turn counter clockwise
while facing sensor tip)

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SERVICING
The 5905/5010 has four user replaceable parts. The motor
assembly can be replaced if it becomes noisy, unbalanced, or
malfunctions. The probe assembly, housing assembly, and stir
paddle can also be replaced if they become damaged.
To disassemble the probe perform the following steps:
1. Remove stir paddle by pulling it straight out.
2. Remove the two screws (A) on the outside of the housing
using a 3/32 Allen wrench.
3. Loosen the top nut of the cable strain relief (B) from the
housing. This will allow the cable to feed through the
housing assembly.
4. Pull the probe and motor assembly out of the housing and
disconnect the two plugs (C).
5. To remove the motor assembly from the probe assembly,
remove the two screws (D) using the 3/32 Allen wrench.

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Housing Assembly
Motor Assembly
Probe Assembly
Stir Paddle
(A)
(B)
(A)
(D) (D)
(C)
(C)
Figure 4 Exploded View of 5905/5010 Probe

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WARRANTY AND REPAIR
YSI Model 5905/5010 Dissolved Oxygen Probes are warranted for one year
from date of purchase by the end user against defects in materials and
workmanship. Electrode cleaning or maintenance is not covered under
warranty. Within the warranty period, YSI will repair or replace, at its sole
discretion, free of charge, any product that YSI determines to be covered by
this warranty.
To exercise this warranty, write or call your local YSI representative, or
contact YSI Customer Service in Yellow Springs, Ohio. Send the product and
proof of purchase, transportation prepaid, to the Authorized Service Center
selected by YSI. Repair or replacement will be made and the product
returned, transportation prepaid. Repaired or replaced products are warranted
for the balance of the original warranty period, or at least 90 days from date
of repair or replacement.
Limitation of Warranty
This Warranty does not apply to any YSI product damage or failure caused
by (i) failure to install, operate or use the product in accordance with YSI’s
written instructions, (ii) abuse or misuse of the product, (iii) failure to
maintain the product in accordance with YSI’s written instructions or
standard industry procedure, (iv) any improper repairs to the product, (v) use
by you of defective or improper components or parts in servicing or repairing
the product, or (vi) modification of the product in any way not expressly
authorized by YSI.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED OR IMPLIED, INCLUDING ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
YSI’s LIABILITY UNDER THIS WARRANTY IS LIMITED TO
REPAIR OR REPLACEMENT OF THE PRODUCT, AND THIS SHALL
BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY DEFECTIVE
PRODUCT COVERED BY THIS WARRANTY. IN NO EVENT SHALL
YSI BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES RESULTING FROM ANY
DEFECTIVE PRODUCT COVERED BY THIS WARRANTY.

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AUTHORIZED U.S. SERVICE CENTERS
For the nearest authorized service center contact
YSI Technical Support •1725 Brannum Lane •Yellow
Springs, Ohio •45387 •Phone: [phone]•[phone] (US)
Fax: [phone] •E-Mail: [e-mail]
www.ysi.com

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CLEANING INSTRUCTIONS
NOTE: Before they can be serviced, equipment exposed to
biological, radioactive, or toxic materials must be cleaned
and disinfected. Biological contamination is presumed for
any instrument, probe, or other device that has been used with
body fluids or tissues, or with wastewater. Radioactive
contamination is presumed for any instrument, probe or other
device that has been used near any radioactive source.
If an instrument, probe, or other part is returned or presented
for service without a Cleaning Certificate, and if in our
opinion it represents a potential biological or radioactive
hazard, our service personnel reserve the right to withhold
service until appropriate cleaning, decontamination, and
certification has been completed. We will contact the sender
for instructions as to the disposition of the equipment.
Disposition costs will be the responsibility of the sender.
When service is required, either at the user's facility or at YSI,
the following steps must be taken to insure the safety of our
service personnel.
1. In a manner appropriate to each device, decontaminate all
exposed surfaces, including any containers. 70% isopropyl
alcohol or a solution of 1/4 cup bleach to 1 gallon tap
water are suitable for most disinfecting. Instruments used
with waste water may be disinfected with .5% Lysol if this
is more convenient to the user.
2. The user shall take normal precautions to prevent
radioactive contamination and must use appropriate
decontamination procedures should exposure occur.

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3. If exposure has occurred, the customer must certify that
decontamination has been accomplished and that no
radioactivity is detectable by survey equipment.
4. Any product being returned to the YSI Repair Center,
should be packed securely to prevent damage.
5. Cleaning must be completed and certified on any product
before returning it to YSI.
PACKING INSTRUCTIONS
1. Clean and decontaminate items to insure the safety of the
handler.
2. Complete and include the Cleaning Certificate.
3. Place the product in a plastic bag to keep out dirt and
packing material.
4. Use a large carton, preferably the original, and surround
the product completely with packing material.
5. Insure for the replacement value of the product.