Campbell Scientific CS512
Oxyguard Type III
Dissolved Oxygen Probe
Revision: 12/06
C o p y r i g h t
©
2 0 0 1 - 2 0 0 6
C a m p b e l l S c i e n t i f i c , I n c .
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CS512 Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
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1. General Information.....................................................1
2. Specifications ..............................................................2
3. Optional Probe Accessories.......................................3
4. Optional Agitator .........................................................3
5. Application Information ..............................................4
6. Wiring............................................................................4
7. Programming ...............................................................5
8. Calibration....................................................................6
9. Maintenance.................................................................7
10. Agitator Control .........................................................7
Appendix
A. Dissolved Oxygen in Fresh Water Table............... A-1
Figures
1-1. CS512......................................................................................................1
4-1. Preventing Bio-fouling of the CS512......................................................3
4-2. CS512 with PT4 Agitator........................................................................4
10-1. Agitator Wiring .....................................................................................7
Table
6-1. Sensor Wiring..........................................................................................4
i
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CS512 Table of Contents
Examples
1. Sample Program using P1.......................................................................... 5
2. Sample Program using P2.......................................................................... 5
3. Sample Program using VoltSE .................................................................. 5
4. Sample Program using VoltDiff ................................................................ 5
5. Sample Program using VoltSE .................................................................. 5
6. Sample Program using P36........................................................................ 6
7. Sample Program using Expression ............................................................ 6
8. Sample Program using P86 and P22 Instructions ...................................... 8
9. Sample Program using Portset ................................................................... 8
10. Sample Program using Portset ................................................................. 8
ii
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Campbell Scientific CS512 Oxyguard
Type III Dissolved Oxygen Probe
An accurate and reliable sensor is a critical element in any measurement system. The
Oxyguard Stationary Probe meets these criteria for the measurement of dissolved oxygen.
1. General Information
The Oxyguard Stationary Probe is a galvanic probe which produces a millivolt
signal proportional to the amount of oxygen present in the measured medium.
Oxygen diffuses through the membrane onto the cathode, reacts chemically, and
combines with the anode. An electrical current is produced by this chemical
reaction which is converted from microamps to millivolts by an in-line resistor.
An in-line thermistor also conditions the signal providing automatic temperature
compensation. With these features, the probe produces a millivolt output
proportional to the oxygen present in the medium in which it is placed. The probe
consists of two parts, an upper part with cathode, anode and cable, and a lower part
comprising a screw on membrane cap with fitted membrane. The cap is filled with
electrolyte and simply screwed onto the top component.
The probe is self-polarizing and requires no external power source. There are two
wires to connect.
Because the probe's output is linear, it is possible to connect it directly to a data
acquisition system capable of handling the small millivolt signal.
The probe's robust construction and simple design make maintenance and
servicing it straightforward. There is no need to send the probe back to the factory
for servicing. It utilizes a strong, easy-to-clean and easy-to-change membrane in a
screw-on membrane cap. Regular servicing is not required. When necessary the
probe can be fully overhauled in five minutes.
FIGURE 1-1. CS512
1
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
2. Specifications
Principle of Measurement:
Membrane covered galvanic oxygen probe
2.5 to 5 mV per mg 1-1
Output Signal:
Repeatability:
Better than ±0.2 mg/l calibration temperature
equals measuring temperature ±5°C
Output Impedance:
Response Time:
∼1 kohm
After equilibration, 1 minute for 95% of final
value
Materials of Construction:
Probe body:
Delrin
O-rings:
Membrane O-ring = Buna N
Body Seal O-ring = Viton
0.05 mm (2 mil) Teflon
Membrane:
Dimensions and Weight:
2.28” diameter x 2.3” height
15.9 oz.
Cable:
standard length 7 m (23 ft); other lengths
available upon request
2-wire 22 awg shielded, PVC jacketed
Operating Conditions:
Temperature
0° to 40°C (32° to 122°F)
0 to 29 psig
Pressure:
Minimum Submersion Depth:
Minimum Water Flow:
60 mm (2 ½ in)
1 cm/s (.39 in/sec) across membrane
Calibration:
In air or in air saturated water
Automatic from 4° - 40°C (40° - 104°F)
0-20 mg/l, 0-200% Sat
Temperature Compensation:
Range of Dissolved Oxygen:
Ships with:
5 spare membranes with O-rings
50 ml electrolyte
cathode cleaning pad
2
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
3. Optional Probe Accessories
PT4-L — Agitator for stagnant conditions
18026 — DO electrolyte, 1 liter
18027 — Membrane kit, 10 membranes
4. Optional Agitator
The PT4 Agitator is a reliable and robust agitator for use in conjunction with
probes subjected to bio-fouling in ponds and stagnant water conditions.
O2 probes require a minimum water velocity across their membranes to function
properly. Therefore, to measure DO in stagnant water conditions, it is necessary to
move the water past the membrane to get accurate and reliable DO measurements.
In many instances the water also has a high bio-loading and the probes become
fouled resulting in inaccurate DO measurements.
FIGURE 4-1. Preventing Bio-fouling of the CS512
The PT4 Agitator overcomes these problems. The device is designed so that a soft
bristle brush sweeps across the probe membrane or sensor tip. This sweeping
action of the brush provides the required water velocity as well as prevents the
membrane from becoming bio-fouled.
The optimum sweeping frequency depends upon the design of probe and type of
membrane used and water conditions. An ON-time of 0.25 seconds and OFF-time
of 5 seconds is suitable in most circumstances.
Agitator’s overall size: 7-1/8" x 3-1/4" diameter, 1-1/4 lb. (180mm x 83mm, 0.6 kg)
Supplied with 10 ft. (3 meters) cable.
Power required: 10.5 to 18 VDC at the agitator, 1.1 amps. Maximum ON-time is
3 seconds.
3
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
FIGURE 4-2. CS512 with PT4 Agitator
Optional Repeat Cycle Timer for Agitators: Reciprocating action may be
controlled by the optional solid state Repeat Cycle Timer. It sends 12 VDC pulses
to the agitator coil. The ON-time is 0.25 sec. The OFF-time is adjustable from 3
to 12 sec.; requires supply voltage 10 to 17 VDC; housed in watertight cylinder
6.6" x 2" diameter (170 mm X 50 mm).
5. Application Information
SCWin users: This manual was written primarily for those
whose needs are not met by SCWin. Your procedure is much
simpler: just add the CS512 probe (it’s in the water folder), save
your program, and follow the wiring shown in Step 2 of SCWIN.
NOTE
6. Wiring
The CS512 probe can use one differential channel or one single-ended channel.
Differential wiring is better at rejecting electrical noise and ground loop error.
TABLE 6-1. Sensor Wiring
CR510, CR10X, CR800, CR850,
Colo
r
Functio
n
CR23X, CR1000, CR3000
CR200 Series
Whit
e
Signal +
Differential High,
or Single-Ended Channel
Single-Ended
Channel
Blue
Signal -
Differential Low or AG
Ground
4
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
7. Programming
In the CR510, CR10X, and CR23X datalogger, Instruction P1 or P2 can be used.
Example 1 uses a single-ended measurement for the CS512 probe; example 2 uses
a differential measurement. The example measurement instructions that follow do
not store data to final storage. Additional instructions (typically P92, P77, and
output processing instructions such as P70) are required to store data permanently.
EXAMPLE 1. Sample Program using P1
1: Volt (SE) (P1)
1:
1
Reps
2: 24
250 mV 60 Hz Rejection Range ; code 23 used for CR23X
3:
4:
5: 1.0
6: 0.0
1
1
SE Channel
Loc [ DOmV
Multiplier
Offset
]
*See Calibration*
EXAMPLE 2. Sample Program using P2
1: Volt (Diff) (P2)
1:
1
Reps
2: 24
250 mV 60 Hz Rejection Range ; code 23 used for CR23X
3:
4:
5: 1.0
6: 0.0
1
1
DIFF Channel
Loc [ DOmV
Multiplier
Offset
]
*See Calibration*
In the CR1000, CR800, CR850, and CR3000 dataloggers, instruction VoltDiff
or VoltSE is used to measure the CS512 probe.
EXAMPLE 3. Sample Program using VoltSE
VoltSE (DOmV,1,mV250,1,1,0,_60Hz,1.0,0)
EXAMPLE 4. Sample Program using VoltDiff
VoltDiff (DOmV,1,mV250,1,True ,0,_60Hz,1.0,0)
In the CR200 series dataloggers, only the instruction VoltSE is used to
measure the CS512 probe.
EXAMPLE 5. Sample Program using VoltSE.
VoltSE (DOmV,1,1,1.0,0)
5
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
8. Calibration
The multiplier is used to calibrate the CS512 probe. To calculate the multiplier:
1) Program the datalogger using a multiplier of one.
2) Place the OxyGuard probe in the air, shaded from the sun. Wait for readings
to stabilize. This may take 15 minutes or more.
3) Determine the air temperature and barometric pressure.
4) Using a calibration chart such as that provided in the probe’s manual,
determine the oxygen concentration of the air.
5) Use the following equation to calculate the multiplier:
M = P/R
M = Multiplier
P = Concentration in PPM of the air (from the calibration chart in Appendix A)
R = The signal output of the OxyGuard probe when using a multiplier of one
6) Change the multiplier in the datalogger program from one to the calculated
number.
A more common way to enter the multiplier is to insert a separate instruction in
the program. This will allow a new multiplier to be added to the program
without rewriting, compiling, and downloading the program to the data logger.
In the CR510, CR10X, and CR23X, use Instruction P36. The multiplier is
entered into an input location called DOmult using the numeric display in
PC200W, PC208W, LoggerNet, PC400, PConnect, PConnectCE, or the
CR10KD.
EXAMPLE 6. Sample Program using P36
57: Z=X*Y (P36)
1:
2:
3:
1
2
3
X Loc [ DOmV
Y Loc [ DOmult
Z Loc [ DOppm
]
]
]
In all dataloggers that use CRBasic, an expression is written. The multiplier
value is entered into the expression through the Public Table using the numeric
display in PC200W, LoggerNet, PC400, PConnect, and PConnectCE.
EXAMPLE 7. Sample Program using Expression
DOppm = DOMult * DOmV
6
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
9. Maintenance
The CS512 probe needs little maintenance. Regular cleaning of the membrane is
all that is required. The membrane is very durable and can be cleaned with a cloth
or soft paper. Do not scratch it clean with your fingernail.
10. Agitator Control
In low flow conditions (less than about 5 cm/sec), it may be necessary to add
an agitator to the CS512 probe. Campbell Scientific ships the agitator with a
repeat cycle timer. Using the repeat cycle timer requires no datalogger
programming. However, some users choose to use a solid state relay and have
the datalogger agitate the water on the probe face either periodically
throughout the day or just before measurement. Agitating just before the
measurement saves on power and causes less wear and tear on the agitator and
probe membrane.
The wiring for the agitator as controlled by this example program would be as
follows:
BLACK
1
Ground/G
Datalogger
4
3
Agitator
#7321 Relay
Crydom D1D07
Port C1
WHITE
2
+
-
12 V Battery
FIGURE 10-1. Agitator Wiring
The following instructions would trigger the agitator as discussed in the
agitator manual.
In the CR510, CR10X, and CR23X, use instruction P86 and P22.
7
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Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe
EXAMPLE 8. Sample Program using P86 and P22 Instructions
45: Do (P86)
1: 41
Set Port 1 High
46: Excitation with Delay (P22)
1:
1
Ex Channel
2: 20
Delay W/Ex (units = 0.01 sec)
Delay After Ex (units = 0.01 sec)
mV Excitation
3:
4:
0
0
47: Do (P86)
1: 51
Set Port 1 Low
48: End (P95)
In the CR200 series dataloggers, use the Portset instruction.
EXAMPLE 9. Sample Program using Portset
Portset (1,1)
Delay(500,msec)
Portset(1,0)
In the CR1000, CR800, CR850, and CR3000 dataloggers, use the Portset
instruction.
EXAMPLE 10. Sample Program using Portset
Portset (1,1)
Delay (1,500,msec)
Portset (1,0)
The above example is not as power efficient as possible and would require AC
power to maintain a sufficient battery charge. If it is necessary to operate an
agitator without AC power available, write the program so that the agitator is
only operated for a short period of time just before the measurement is to be
taken.
8
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Appendix A. Dissolved Oxygen in
Fresh Water Table
A-1
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Appendix A. Dissolved Oxygen in Fresh Water Table
A-2
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