IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Concerns in pH # 6: High Purity pH CONTROLS

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS PROBLEM High purity water has a very high impedance. The high impedance of the water combined with the high impedance of the glass measuring electrode makes the pH signal susceptible to electrostatic interference and sluggish response.

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Solution Model high purity pH panel or model ultra-high purity (less than 1 µScm -1 ) panel

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS pH Tip Configuration Reference Flat Glass Stem Reference Junction SS Flow cell

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Flat surface reduces path length between glass and reference for reduced impedance Flat surface allows small volume at electrode tip Flat surface close to inlet allows fast sample response Stainless Steel flow cell can be used for differential measurement technique and eliminate electrostatic pickup. Use low conductivity buffers for quicker response after calibration pH Tip Configuration

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS 1 mm separation Short path length between the glass and the reference minimizes impedance and will speed response time.

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS 1 ml volume at sensor tip Small sample volume at the tip allows fast sample turnover. Also, connection between the glass and reference is accomplished by KCl that leaches into the sample from the reference. The smaller the sample volume, the better the connection between the glass and reference.

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Ultra-high purity applications are susceptible to electrostatic interference. The model has a differential pre-amplifier which uses the stainless steel flow cell as a third electrode. The differential pre-amp measures the mV potential between the glass and flow cell and then the reference and flow cell and subtracts the two values. Thus, the electrostatic interference is eliminated from the measurement. mV measurement between glass and flow cell then reference and flow cell.

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Pressure and Flow Fluctuating pressure and flow will have an effect on the stability of the pH measurement. As the KCl from the reference is the conductor, fluctuation of the pressure or flow will allow varying amounts of KCl to flow out of the reference. The varying flow will be read by the pH electrode as varying conductivity and the pH meter will show “jumpy” readings. Pressure and flow regulation is standard for both the and to create better pH stability.

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS When calibrating, it is important to use the proper standards for best accuracy and quick response. As the conductivity of the sample is low, if normal pH buffers are used they will be absorbed into the reference junction and take a long time to to purged. By using low conductivity buffers, excellent accuracy and speed of response will be accomplished after calibration. Calibration

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Low sample volume Short path length between the glass and reference Differential measurement in ultra-pure applications Pressure and flow regulation Low conductivity buffers available Proven Technology Superior Design Better Results IC Controls High Purity pH

IC Controls Quality Water Solutions for pH pH / ORP Conductivity Dissolved Oxygen Chlorine Standards R1.0 © 2004 IC CONTROLS Sensor and Flow cell For more information: Call: or We will be happy to help you directly or put you in contact with your local Representative of IC Controls Qualitiy Water Products