Hach-Lange 5740 sc User Manual

DOC023.52.03250.May05

5740 sc Galvanic Membrane

Dissolved Oxygen Sensor

User Manual

DOC023.52.03250.May05

5740 sc Galvanic Membrane

Dissolved Oxygen Sensor

User Manual

Table of Contents

Section 1 Specifications ........................................................................................................................................ 3

Section 2 General Information............................................................................................................................... 5

2.1 Safety Information............................................................................................................................................... 5

2.1.1 Use of Hazard Information......................................................................................................................... 5

2.1.2 Precautionary Labels................................................................................................................................. 5

2.2 General Sensor Information................................................................................................................................ 6

2.3 Theory of Operation ........................................................................................................................................... 6

Section 3 Installation .............................................................................................................................................. 7

3.1 Connecting the Sensor to an sc Controller ......................................................................................................... 7

3.1.1 Attaching a sc Sensor with a Quick-connect Fitting .................................................................................. 7

3.2 Installing the Sensor in the Sample Stream........................................................................................................ 8

3.2.1 Sensor Installation Requirements.............................................................................................................. 8

Section 4 Operation ............................................................................................................................................. 11

4.1 Using an sc Controller....................................................................................................................................... 11

4.2 Sensor Setup ................................................................................................................................................... 11

4.3 Sensor Data Logging ........................................................................................................................................ 11

4.4 Pressure and Elevation..................................................................................................................................... 11

4.4.1 Selecting Atmospheric Pressure ............................................................................................................. 12

4.5 SENSOR STATUS Menu.................................................................................................................................. 12

4.6 SENSOR SETUP Menu .................................................................................................................................... 12

4.7 Calibration......................................................................................................................................................... 14

4.7.1 Calibration in Air ...................................................................................................................................... 14

4.7.2 Sample Cal—Calibration by Comparison to a Winkler Titration .............................................................. 15

4.7.3 Sample Cal—Calibration by Comparison to a Hand-held DO Analyzer .................................................. 16

4.7.4 Concurrent Calibration of Two Sensors................................................................................................... 16

Section 5 Maintenance ......................................................................................................................................... 19

5.1 Maintenance Schedule ..................................................................................................................................... 19

5.2 Cleaning the Sensor ......................................................................................................................................... 19

5.2.1 Cleaning the Galvanic Sensor ................................................................................................................. 19

5.3 Preventing the Sensor Membrane from Drying Out.......................................................................................... 19

5.4 Replacing the Sensor Assembly ....................................................................................................................... 20

Section 6 Troubleshooting................................................................................................................................... 21

6.1 Error Codes ...................................................................................................................................................... 21

6.2 Warnings .......................................................................................................................................................... 21

6.3 Sensor Troubleshooting ................................................................................................................................... 22

Section 7 Replacement Parts ............................................................................................................................. 23

7.1 Replacement Items ........................................................................................................................................... 23

7.2 Accessories....................................................................................................................................................... 23

Section 8 Warranty, liability and complaints...................................................................................................... 25

8.1 Compliance Information .................................................................................................................................... 26

Section 9 Adresses ............................................................................................................................................. 27

Appendix A Modbus Register Information

Index....................................................................................................................................................................... 31

........................................................................................................ 29

Table of Contents

Section 1 Specifications

Specifications are subject to change without notice.

Components Corrosion-resistant materials, fully-immersible probe with 10 m (30 ft) cable

Measuring Range (Dissolved Oxygen) 0 to 40 ppm (0 to 40 mg/L) or 200 % saturation

Measuring Range (Temperature) – 5 to 50 °C (23–120 °F)

Probe Operating Temperature – 5 to 50 °C (23–120 °F)

Probe Storage Temperature – 5 to 70 °C (23–158 °F); 95 % relative humidity, non-condensing

Response Time at 20 °C 120 seconds to 90 % of value upon step change

Measurement Accuracy ± 2 % of span

Temperature Accuracy ± 0.2 °C

Temperature Compensator 30K NTC Thermistor

Repeatability ± 0.5 % of span

Sensitivity ± 0.5 % of span

Calibration Air/Sample

Maximum Pressure 10 bar (145 psi)

Probe Cable Length Integral 33 ft (10 m)

Probe Weight 0.26 kg (9.1 oz)

Probe Dimensions See Figure 3 Probe Dimensions on page 8.

Wetted Materials Noryl, PVC, Viton, Polypropylene, Nylon

Electrode Materials Nickel-chrome and lead

Minimum Flow Rate 0.5 cm/s (0.016 ft/s)

Measuring Principle Galvanic

Specifications

Section 2 General Information

2.1 Safety Information

Please read this entire manual before unpacking, setting up, or operating this equipment. Pay attention to all danger and caution statements. Failure to do so could result in serious injury to the operator or damage to the equipment.

Do not use or install this equipment in any manner other than that specified in this manual.

2.1.1 Use of Hazard Information

DANGER Indicates a potentially or imminently hazardous situation which, if not avoided, could result in death or serious injury.

CAUTION Indicates a potentially hazardous situation that may result in minor or moderate injury.

Important Note: Information that requires special emphasis.

Note: Information that supplements points in the main text.

2.1.2 Precautionary Labels

Read all labels and tags attached to the instrument. Personal injury or damage to the instrument could occur if not observed

This symbol, if noted on the instrument, references the instruction manual for operation and/or safety information.

This symbol, when noted on a product enclosure or barrier, indicates that a risk of electrical shock and/or electrocution exists.

This symbol, if noted on the product, indicates the need for protective eye wear.

This symbol, when noted on the product, identifies the location of the connection for Protective Earth (ground).

This symbol, when noted on the product, identifies the location of a fuse or current limiting device.

Electrical equipment marked with this symbol may not be disposed of in European public disposal systems after 12 August of 2005. In conformity with European local and national regulations (EU Directive 2002/96/EC), European electrical equipment users must now return old or end-of life equipment to the Producer for disposal at no charge to the user.

Note: For all electrical products (marked or unmarked) which are supplied or produced by Hach-Lange, please contact the local Hach-Lange sales office for instructions for proper disposal.

General Information

2.2 General Sensor Information

The Galvanic Membrane Dissolved Oxygen Sensor allows aqueous samples to be easily and accurately analyzed for dissolved oxygen concentration. The system consists of a controller with an integrated display and a sensor for in-situ measurement.

Optional equipment, such as mounting hardware for the probe, is supplied with instructions for all user installation tasks. Several mounting options are available, allowing the probe to be adapted for use in many different applications.

Typical applications include aeration basins, nutrient removal in equalization basins, aerobic and anaerobic digesters, effluent streams, rivers, lakes, and fish ponds.

2.3 Theory of Operation

This galvanic oxygen sensor operates as a battery generating a voltage. The resulting voltage is directly proportional to the dissolved oxygen concentration. The cell is constructed with a fine wire coil cathode wrapped around a lead anode. A salt solution fills the void between the anode and cathode. The sensor is contained by a cylindrical membrane held in close proximity to the wire coil.

Oxygen from the solution to be tested enters the cell by diffusion through the membrane and then across the thin electrolyte layer to the cathode. The oxygen is reduced at the cathode as shown in reaction 1.

O22H2O4e

++ 4OH

–

→

–

The cathode is at such a negative potential that it reduces all the oxygen that diffuses to its surface. The lead anode is oxidized to give an overall reaction that produces lead hydroxide as shown in reaction 2.

2Pb 4OH

–

+ 2Pb OH()24e–+→

The overall result of this reaction is the consumption of the lead anode as current flows, yielding a very sensitive electrode that can detect changes at the microvolt level.

Section 3 Installation

DANGER Only qualified personnel should conduct the installation tasks described in this section of the manual.

3.1 Connecting the Sensor to an sc Controller

3.1.1 Attaching a sc Sensor with a Quick-connect Fitting

The sensor cable is supplied with a keyed quick-connect fitting for easy attachment to the controller (Figure 1). Retain the connector cap to seal the connector opening in case the sensor must be removed. Optional extension cables may be purchased to extend the sensor cable length. If the total cable length exceeds 100 m (300 ft), a termination box must be installed.

Note: Use of a load termination box other than Cat. No. 5867000 may result in a hazard.

Figure 1 Attaching the Sensor using the Quick-connect Fitting

Figure 2 Quick-connect Fitting pin assignment

Number Designation Wire Color

1+12 VDC Brown 2 Circuit Common Black 3 Data (+) Blue 4 Data (–) White 5 Shield Shield (grey wire in existing quick-disconnect fitting) 6Groove

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