YSI 6-Series Environmental Monitoring Systems

1. 6-Series Training Seminar YSI 6-Series EnvironmentalMonitoringSystems

2. Overview • YSI • 6-Series Products • Sensor Technology • 650 MDS • Care & Maintenance • Calibration • Tips & Tricks

3. YSIYellow Springs Instrument CompanyYSI Environmental

4. YSI • Established 1948 • 2003 Revenue >$64 Million • ISO 9001 & ISO 14001 Certified • ESOP Company (Employee Stock Ownership Plan) • Core Competency- Sensor Measurement Technology

5. YSI

6. YSI • 1952 - Developed first quartz crystal electronic stopwatch • 1952 - Developed first practical medical electronic thermometer • 1955 - Developed first interchangeable thermistor temperature probe • 1956 - First commercial heart - lung machine

7. YSI • 1957 - First instantaneous blood-gas analyzer • 1961 - First line of precision interchangeable thermistors • 1963 - First practical D.O. meter for field and lab • 1972 - First immobilized enzyme polarographic sensor

8. YSI • 1981 - First superior - stability thermistor • 1982 - First whole-blood L-Lactate analyzer • 1987 - First laboratory outside Germany accredited by the German Federal Bureau of Standards • 1993 - First long-term in situ stirring-independent oxygen sensor

9. 6-Series Products

10. 6-Series Products • 600QS • 600LS • 600OMS • 600R • 600XL/600XLM • 6820/6920 • 6600/6600EDS • ADV6600

11. 600 QS (Quick Sample)

12. 600XL, 600XLM, 600 OMS

13. 600LS

14. 6820, 6920

15. 6600

16. 6600EDS

17. ADV6600

18. 556 MPS

19. Sensor Technology

20. Sensor Technology • Turbidity • Chlorophyll • Rhodamine • PAR - Photosynthetically Active Radiation • Chloride • Ammonia • Nitrate • Dissolved Oxygen • Temperature • Conductivity • pH • ORP • Water Depth / Level • SonTek Sensors

21. Temperature • High precision thermistor • 2252 ohms at 25C (+/- 1%) • Resistance changes with temperature - uses thermistor algorithm to convert to temperature • Thin wall titanium sleeve • Fast response • Resists corrosion

22. Conductivity • AC voltage applied to nickel electrodes • Conductivity electrodes placed in sample to be measured • Current flows through the electrodes and the sample • Current level has direct relationship with conductivity of the solution

23. Conductivity • 4 pure nickel electrodes • Cell constant = 5.00 • Temperature probe • Fresh, brackish and sea water capability

24. Conductivity • Conductivity will vary with temperature changes • Specific Conductance is commonly expressed • Specific Conductance = Conductivity corrected to 25°C.

25. Dissolved Oxygen • Two main types of Polarographic Oxygen Sensors : Steady State Pulsed

26. Dissolved Oxygen O2 H2O H2O O2 H2O O2 H2O O2 e- e- H2O O2 Teflon membrane O2 Silver Anode H2O e- e- H2O O2 KCl H2O O2 Gold Cathode H2O H2O O2 H2O O2 O2 H2O H2O • Oxygen diffuses through Teflon membrane • Oxygen reduced at gold cathode • Electrons flow = electrical signal • Oxygen concentration proportional to signal level

27. Rapid Pulse Dissolved Oxygen • Based on Clark polarographic probe • Concept of pulsed sensors is not new • First scientific papers written in 1985 • Required complicated calibration procedures

28. Rapid Pulse Dissolved Oxygen 40ms on off 3960ms 4 sec • Rapid-Pulse refined the technology • Pulses on / off during measurement sequence • Incorporates new electrode design • Utilizes digital electronics • Eliminates need for stirring

29. Rapid Pulse Dissolved Oxygen • Long Term Stability • Less susceptible to fouling • accurate long term data • Accurate results in low flow conditions • no stirring device required, <2% stirring dependence • Ultra low power requirements • long battery life • Reliable long term deployments • Diagnostics • Serviceable

30. Rapid Pulse Dissolved Oxygen Removed Stirring 100 Percent Saturation Rapid Pulse Response Steady State Response

31. YSI Rapid-Pulse vs. Steady State

32. The Last 100 Hours Rapid Pulse Steady State

33. pH • Glass sensing bulb is filled with solution of stable pH (usually 7) so inside of glass surface experiences constant binding of H+ ions • Outside of bulb is exposed to sample where H+ varies • Differential of H+ creates a potential which is read versus the stable potential of the reference electrode

34. pH AgCl-coated Ag wire H+ H+ H+ H+ H+ H+ KCl Gel Emembrane Reference Junction

35. pH • The potential is related to the pH by a form of the Nernst Equation • E = Eo + (constant) * T * pH where T is in degrees Kelvin • Plot of pH versus voltage is linear and is used to convert the voltage to pH • Slope of plot (constant * T) at temperatures different from calibration is predictable from equation

36. pH • Plot - Nernst Equation pH 4.0 +177 slope pH 7.0 0 +/- 50mV pH 10.0 -177 slope

37. ORP • Oxidation reduction potential (ORP) of the sample is determined by measuring the potential of a chemically-inert (platinum) electrode which is immersed in the solution • The sensing electrode potential is read relative to the reference electrode of the pH probe and the value is presented in millivolts • Value represents the overall oxidizing (positive values) and reducing (negative values) ability of the sample

38. ISEs • Works exactly like pH except the sensor is a PVC membrane selective for the analyte rather than a glass bulb selective for H+ ions • Sensor module contains a static concentration of the analyte which binds to the inner membrane • Potential is related to the analyte concentration using the Nernst Equation

39. ISEs pH Reference Electrode ISE Module - + AgCl-coated Ag wire NH4+ solution PVC membrane with ionpore NH4+ NH4+ NH4+ Emembrane NH4+ NH4+ NH4+

40. Optical Probes Wiper Motor Wiper Sponge Wiper

41. Turbidity Techniques Nephlometric Angle of Reflection 90 ISO Recommended method

42. Turbidity: ISO-7027 Method • Probe contains an LED with a wavelength of 860 NM (Emitter) • Probe contains a photodiode (detector) • Optical fibers connected to emitter and detector intersect probe face at opposing 45 degree angles - net angle is 90 degrees • Light from emitter enters sample and scatters off the particles - light scattered at 90 degrees enter detector fiber and is measured by the photodiode

43. Turbidity • Circuit board in the sonde quantifies sample signal relative to standards and generates a value in NTU • Circuit board also controls the mechanical wiper - automatically rotates in unattended mode; also triggered manually from keyboard in discrete mode or during calibration

44. Turbidity Photodetector Light Source (infrared) Fiber optic cables molded at a 45 degree angle 90º Intersect

45. Chlorophyll • Chlorophyll fluoresces when irradiated with light of a particular wavelength (435-470 nm), emits light of a higher wavelength (630-700 nm) • The ability of chlorophyll to fluoresce is the basis of commercial in-situ fluorometers. • These fluorometers induce chlorophyll to fluoresce by shining a beam of light of the proper wavelength into the water and then measuring the higher wavelength light which is emitted. • Measurement is made in the field without disrupting cells

46. YSI 6025 Chlorophyll Probe Photodetector Light Source 470 nm Optical Filter Optical Fiber

47. Rhodamine • Probe contains an LED with a wavelength of 540 nm (Emitter) • Probe contains a photodiode (detector) • Optical fibers connected to emitter and detector • Light from emitter enters sample and the Rhodamine WT dye in the sample fluoresces. • Probe picks up the high wavelength emission, and uses filter to restrict other source of emission.

48. Rhodamine Light Source Fiber optic cables 90º Intersect Photodetector Optical Filter

49. Depth Sensor • Sensor: Stainless Steel Strain Gauge in three different sensitivities - shallow, medium and deep. • Shallow 0-9.1m ± 0.02m • Medium 0-60.5m ± 0.12m • Deep 0-200m ± 0.3m (YSI 6600 only) • Voltage from Strain Gauge is proportional to hydrostatic pressure.

50. Non-Vented Depth Measurement Pressure Due to Atmosphere Pressure Due to Water Column PTotal = PWater + PAtmosphere