Campbell Scientific CS510 User Manual

INSTRUCTION MANUAL

CS510 Oxyguard

Dissolved Oxygen Probe

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Copyright (c) 2000

Campbell Scientific, Inc.

The CS510-L Oxyguard Dissolved Oxygen Probe is manufactured by Point Four Systems
Incorporated. Point Four’s conditions of sale and return policy apply to these items.

Products may not be returned without prior authorization. To obtain an RMA number
contact Point Four Systems, Inc., phone [phone]. NOTE: if the product has been
exposed to hazardous media, it must be fully decontaminated and neutralized prior to
return to Point Four Systems.

CS510 OxyGuard 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 t o th e amount of oxygen present in th e measured medium.
Oxygen diffuses through the membrane onto the cathode, reacts chemically, and
combines with th e an ode. An electrical current is produced by th is ch emical
reaction which is converted from microam ps to m illivolts by an in- lin e resistor.
An in-line thermistor also conditions the signal providing autom atic temperature
compensation. With these features, the probe produces a millivolt output
proportional to the oxygen presen t in th e medium in w h ich it is placed. The probe
consists of two parts, an upper part w i th cat h ode, an ode an d cabl e, an d a l ower
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 n o ex tern al power source. There are only
two wires to connect. Cable length is rarely a limiting factor and generally there is
no need for shielded wi re.

Because the probe's output is lin ear, it is pos s ible to con n ect it directly to a data
acquisition system capable of handling the sm all 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 th e f actory
for servicing. It utilizes a strong, easy-to-clean and easy-to-change membrane in a
screw-on membrane cap. Regular serv icin g is n ot requ ired. When n eces s ary probe
can be fully overhauled in five minutes.

FIGURE 1-1. CS510-L

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CS510 OxyGuard Dissolved Oxygen Probe

2. Specifications

Principle of Measurement: Membrane covered polarographic oxygen probe—

self polarizing galvanic cell
Output Signal: 5 mV per mg/l, 2 mV per %/vol nominal
Accuracy: Better than +/- 2 % of reading +/- 1 digit when calibration

temperature equals measuring temperature +/- 5 C
Repeatability: Better than +/- 0.2 mg/l; Better than +/- 0.5 %/vol when

barometric pressure unchanged
Output Impedance: 1 kOhm nominal
Response Time:

mg/l: 60 s for 90 % of 100 % step change at constant temperature

%vol: 10 s for 90 % of 100 % step change at constant temperature
Materials of Construction:

Probe body: POM (polyoxymethylene)

O-rings: Viton

Membrane: 0.05 mm (2 mil) Teflon
Dimensions and Weight :

58 mm diameter by 59 mm high (2-1/4 inch diameter by 2-1/4 inch high)

350 g (3/4 lb) including standard 3 m (10 ft) cable length
Cable: 2-conductor, 0.75 square mm (16 gauge), standard length 3 m (10 ft);

other lengths available upon request
Operating Conditions: Temperature: 0 to 50 C (32 to 122 F)
Pressure: Maximum 10 atmospheres (147 psig)
Minimum Submersion Depth: 60 mm (2 ½ in)
Minimum Water Flow: 2.5 cm/s (1 in/sec) across membrane
Calibration: In air or in air saturated water. Use of EasyCal calibrator optional.
Temperature Compensation: Automatic f rom 4 - 40 C (40 - 104 F)

Probe Options:

Type I Type II

Range of dissolved oxygen 0-50 mg/l, 0-500 % Sat 0-15 mg/l, 0-150 % Sat
Gaseous oxygen 0-100 %/vol 0-35 %/vol
Electrode materials Ag cathode/Zn anode Ag cathode/Pb anode
Probe electrolyte NaCl Na

2CO3

2

3. Service Kit

CS510 OxyGuard Dissolved Oxygen Probe

Spare membrane cap with fitted membrane.
50 ml electrolyte.
Spare anode and O-ring.

FIGURE 3-1. Exploded View of CS510-L

4. Optional Probe Accessories

Agitator for stagnant conditions.
Probe Mounting assembly for waste water installations .
Flow-through and by-pass fittings.
EasyCal calibrator for fast and accu rate calibration .

5. 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.

probes require a minimum water velocity across their m embranes to function

O

2

properly. Therefore, to measure DO in stagnant water conditions, it is n ecessary to
move the water past the membrane to get accurate and reliable DO measurements.
In many in s tan ces th e water also has a high bio-loadin g an d th e probes become
fouled resulting in inaccu rate DO measurements.

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CS510 OxyGuard Dissolved Oxygen Probe

The PT4 Agitator overcomes these problem s . The devi ce is des ig n ed s o th at a sof t
bristle brush sweeps across the probe m embrane or sensor tip. This s weeping
action of the brush provides the required water velocity as well as prevents th e
membrane from becoming bio-fouled.

FIGURE 5-1. Preventing Bio-fouling of the CS510-L

The optimum s weeping frequen cy depends upon the des ig n of probe and type of
membrane used and water conditions. A n ON- time of 0.25 seconds and OFF-time
of 5 seconds is suitable in m os t circu mstances.

Agitator’s ov eral l si ze: 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.

FIGURE 5-2. CS510-L with PT4 Agitator

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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).

6. Application Information

CS510 OxyGuard Dissolved Oxygen Probe

NOTE

7. Wiring

8. Programming

*1 Table 1

01: 15 Sec. Execution Interval

Short Cut users: This application note was written primarily for
those whose needs are not met by Short Cut. Your procedure is
much simpler: just add the OxyGuard probe (it’s in the water
quality sensor group), save your program, and follow the wiring
shown in Step 4 of Short Cut.

The OxyGuard probe uses one differential channel. Differen tial wiring is better at
rejecting electrical noise and g rou nd loop error.

Red------------------1H
Blue -----------------1L

Instruction 2, differential millivolt measuremen t is required for the Oxy Gu ard
probe. 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 s t ore data permanently.

01: Volt (Diff) (P2)

01: 1 Rep
02: 24 250 mV
03: 1 Diff Chan
04: 1 Loc: [DO ]
05: 1 Mult. *See calibration*
06: 0 Offset

9. Calibration

The multiplier is used to calibrate the OxyGuard probe. To calculate the
multiplier:

1) Program the CR10(X) using a multiplier of one.

2) Place the OxyGuard probe in the air, sh aded f rom the sun. Wait for readings

to stabilize. This may take 15 minutes or more.

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CS510 OxyGuard Dissolved Oxygen Probe

3) Determine the air temperature an d barometric pressure.

4) Using a calibration chart such as that provided in the probe’s manual,

determine the oxyg en con cen tration of th e air.

5) Use the following equation to calculate the m u ltiplier:

M = P/R
M = Multiplier
P = Concentration in PPM of the air (from the calibration chart)
R = The signal output of the OxyGuard probe when u sin g a multiplier of one

6) Change the multiplier in the CR10 program from one to the calculated

number.

10. Maintenance

The OxyGuard probe needs little maintenance. Regular cleaning of the membrane
is all that is required. The membran e is v ery durable and can be cleaned with a
cloth or soft paper. Do not scratch it clean w ith your fingernail. Please see the
OxyGuard manual for com plete maintenance procedures.

11. Agitator Control

In low flow conditions (less than about 2 cm/sec), it may be necessary to add an
agitator to the OxyGuard probe. The distributor for OxyGuard in North
America sells a self-timed a gi t ator which can be pur chased through Campbell
Scientific. The self-timed agitator 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:

Ground/G

Datalogger

Port C1

4 1

#7321 Rela y

Crydom D1D07

3 2

BLACK

Agitator

WHITE

+ -

12 V Battery

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CS510 OxyGuard Dissolved Oxygen Probe

The following instructions in program table 2 would trigger the agitator as
discussed in the agitator manual:

*Table 2 Program

02: 2.0 Execution Interval (seconds)

1: Do (P86)

1: 41 Set Port 1 High ; Use port number as wired

2: Excitation with Delay (P22)

1: 1 Ex Channel
2: 0 Delay W/Ex (units = 0.01 sec)
3: 25 Delay After Ex (units = 0.01 sec)
4: 0 mV Excitation

3: Do (P86)

1: 51 Set Port 1 Low

The above example is not as power efficient as possible, and would require AC
power. 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.

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CS510 OxyGuard Dissolved Oxygen Probe

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