Campbell Scientific CS547 User Manual

INSTRUCTION MANUAL

CS547 Conductivity and

Temperature Probe and

A547 Interface

Revision: 9/00

Copyright (c) 1994-2000

Campbell Scientific, Inc.

Warranty and Assistance

The CS547 CONDUCTIVITY AND TEMPERATURE PROBE AND A547
INTERFACE are warranted by CAMPBELL SCIENTIFIC, INC. to be free

from defects in materials and workmanship under normal use and service for
twelve (12) months from date of shipment unless sp ecified otherwise. Batteries
have no warranty. CAMPBELL SCIENTI F IC, INC.'s obligation under this
warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC,
INC.'s option) defective products. The customer shall assume all costs of
removing, reinstalling, and shipping defective products to CAMPBELL
SCIENTIFIC, INC. CAMPBELL SCIENTIFIC, INC. will return such
products by surface carrier prepaid. This warranty shall not apply to any
CAMPBELL SCIENTIFIC, INC. products which have been subjected to
modification, misuse, neglect, accidents of nature, or shipping damage. This
warranty is in lieu of all other warranties, expressed or implied, including
warranties of merchantability or fitness for a particular purpose. CAMPBELL
SCIENTIFIC, INC. is not liable for special, indirect, incidental, or
consequential damages.

Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs
for customers within their territories. Please visit www.campbellsci.com to
determine which Campbell Scientific company serves your country. To obtain
a Returned Materials Authorization (RMA), contact CAMPBELL
SCIENTIFIC, INC., phone [phone]. After an applications engineer
determines the nature of the problem, an RMA number will be issued. Please
write this number clearly on the outside of the shipping container.
CAMPBELL SCIENTIFIC's shipping address is:

CAMPBELL SCIENTIFIC, INC.

RMA#_____
815 West 1800 North
Logan, Utah 84321-1784

CAMPBELL SCIENTIFIC, INC. does not accept collect calls.

CS547 Probe and A547 Interface
Table of Contents

PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.

1. Overview......................................................................1

1.1 EC Sensor .................................................................................................1

1.2 A547 Interface..........................................................................................1

2. Specifications .............................................................2

2.1 CS547 Probe.............................................................................................2

2.2 A547 Interface..........................................................................................2

2.3 Temperature Sensor..................................................................................3

3. Installation...................................................................3

3.1 Site Selection ............................................................................................3

3.2 Mounting...................................................................................................3

4. Wiring ..........................................................................3

5. Programming ..............................................................4

5.1 Programming Overview............................................................................4

5.2 Measurement Programming......................................................................4

5.3 Correction of Ionization Errors in EC Measurement ................................7

5.4 Correction of Temperature Errors.............................................................8

5.5 Output Processing.....................................................................................9

6. Calibration.................................................................10

6.1 Conversion Factors.................................................................................10

6.2 Typical Ranges .......................................................................................10

6.3 Factory Calibration.................................................................................10

6.4 Field Calibration.....................................................................................10

7. Maintenance..............................................................12

8. Analysis of Errors.....................................................12

8.1 EC Measurement Error...........................................................................12

8.2 Temperature Measurement Error............................................................14

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CS547 Probe and A547 Interface Table of Contents

9. Deriving a Temperature Compensation

Coefficient..............................................................15

10. Instruction 11 Details..............................................15

11. Electrically Noisy Environments............................16

12. Long Lead Lengths Temperature...........................17

13. CS547 Schematic....................................................18

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CS547 Conductivity and Temperature Probe and A547 Interface

1. Overview

The CS547 conductivity and temperature probe, and A547 interface are designed
for measuring the electrical conductivity, dissolved solids, and temperature of
fresh water with Campbell Scientific dataloggers. They require the use of AC
excitation, so they can be used with the CR10(X), 21X, and CR7 dataloggers but
not with the BDR301 or BDR320. Use with multiplexers is possible.

Electrical conductivity (EC) of a solution is a simple physical property, but
measurements can be difficult to interpret. This manual instructs the user how to
make EC measurements with the CS547. Accuracy specifications apply to
measurements of EC in water containing KCl, Na
which are typical calibration compounds, and to EC not yet compensated for
temperature effects.

Statements made on methods of temperature compensation or estimating dissolved
solids are included to introduce common ways of refining and interpreting data, but
are not definitive. Authoritative sources to consult include the USGS Water-Supply
Paper 1473, The pH and Conductivity Handbook published by OMEGA
Engineering, physical chemistry texts, and other sources.

, NaHCO3, and/or NaCl,

2SO4

1.1 EC Sensor

The EC sensor consists of three stainless steel rings mounted in an epoxy tube
as shown in Figure 4-1. Resistance of water in the tube is measured by
excitation of the center electrode with positive and negative voltage.

This electrode configuration eliminates the ground looping problems associated
with sensors in electrical contact with earth ground.

Temperature is measured with a thermistor in a three wire half bridge
configuration.

1.2 A547 Interface

The interface contains the completion resistors and blocking capacitors. The
interface should be kept in a non-condensing environment that is maintained
within the temperature range of the unit.

1

CS547 Conductivity and Temperature Probe and A547 Interface

e

DATALOGGER

AG

SE TEMP

EX TEMP

EX COND

HI COND

LO COND

SHIELD

SHIELD

SENSOR

TEMP

COND

EX COND

EX TEMP

A547 INTERFACE

Logan, Utah

MADE IN USA

FIGURE 1-1. A547 Interface and CS547 Conductivity and Temperature Probe

2. Specifications

2.1 CS547 Probe

Construction
Size

Maximum Cable
Length

Depth Rating
pH Range

The prob e housing is stainless steel
Probe Length: 3.7 inches (94 mm)

Diameter: 0.95 inches (24.13 mm)
1000 ft. The sensor must be ordered with desired length

as cable cannot be added to existing probes.
Maximum 1000 feet
Solution pH of less than 3.0 or greater than 9.0 may damag

the stainless steel ho using.

Electrodes
Cell Constant

Temp. Range of Use
EC Range
Accuracy

2.2 A547 Interface

Size

Temperature Rating

Passivated 316 SS with DC isolation capacitors.
Individually calibrated. The cell constant (K

) is found on

c

a label near the termination of the cable.
0° to 50°C.
Approx. 0.005 to 7.0 mS cm
in KCl and Na

, NaHCO3, and NaCl standards at

2SO4

-1

.

25°C:
±5% of reading 0.44 to 7.0 mS cm

±10% of reading 0.005 to 0.44 mS cm

-1

.

-1

.

Dimensions: 2.5” x .875” x 1.750
Weight: 6 oz.

-15°C to +50°C

2

CS547 Conductivity and Temperature Probe and A547 Interface

2.3 Temperature Sensor

3. Installation

CAUTION

3.1 Site Selection

3.2 Mounting

Thermistor
Range
Accuracy

Rapid heating and cooling of the probe, such as leaving it
in the sun and then submersing it in a cold stream, may
cause irreparable damage.

The EC sensor measures the EC of water inside the stainless steel tube, so
detection of rapid changes in EC requires that the probe be flushed
continuously. This is easy to accommodate in a flowing stream by simply
orienting the sensor parallel to the direction of flow. In stilling wells and
ground wells, however, diffusion rate of ions limits the response time.

The stainless steel housing and sensor cable are made of water impervious,
durable materials. Care should be taken, however, to mount the probe where
contact with abrasives and moving objects will be avoided. Strain on cables
can be minimized by using a split mesh strain relief sleeve on the cable, which
is recommended for cables over 100 ft. The strain relief sleeve is available
from Campbell Scientific as part number 7421.

Betatherm 100K6A1.
0°C to 50°C.
Error ±0.4°C (See Section 8.2).

4. Wiring

WARNING

The A547 is usually mounted in the datalogger enclosure.

The excitation channel used for EC must be separate
from the one used for temperature or measurement
errors will result.

3

CS547 Conductivity and Temperature Probe and A547 Interface

FIGURE 4-1. CS547 Wiring Diagram for Example Below

5. Programming

5.1 Programming Overview

AG
SE3
EX2
EX1
1H

1L

Clear (Shield)
Red (Temp)

Orange (Cond)
Black (Ex Cond)
Green (Ex Temp)

AG

SE TEMP

EX TEMP

EX COND

HI COND

LO COND

SHIELD

SHIELD

TEMP

COND

EX COND

EX TEMP

DATALOGGER SENSOR

Typical datalogger programs to measure the CS547 consist of four parts:

1. Measurement of EC and temperature

2. Correction of ionization errors in EC measurements

3. Correction of temperature errors in EC measurements

4. Output processing

All example programs may require modification by the user to fit the specific
application's wiring and programming needs. All example programs in this
manual are for the CR10(X) and assume that datalogger wire connections are as
follows: the LO COND lead is connected to 1L, the HI COND to 1H, the EX
COND to EX1, the EX TEMP to EX2, and the SE TEMP to SE3 .

5.2 Measurement Programming.

EC: Results from Instructions 5 or 6 (chosen automatically as part of the
autoranging feature of the following program segment) are processed with
Instruction P59 to produce the resistance across the electrodes:

Input Location Labels

Definitions for the following program:
Rs Solution resistance
Rp Resistance of leads/cable and blocking caps
Ct Solution EC with no temp. correction
C25mScm_1 EC corrected for temperature

4