Key Features of O2 Sensors
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APPLIED SENSING TECHNOLOGIES Key Features of O2 Sensors Oxygen sensors are typically small in size and the operating life of the sensor strictly depends upon the rate at which the anode is consumed, which in turns depends upon the rate at which oxygen reaches at the sensing element. The design of the sensor is a compromise between the oxygen level being sensed and the amount of Pb needed to achieve sensor operating life to a reasonable time, typically 12-60 months. Depending upon the gas limiting barrier used, oxygen sensors generate current signal from low to high uA per unit oxygen concentration. To measure oxygen in sub-PPM level, a higher current signal is needed for good signal to noise ratio. On the other hand, to measure oxygen in the percent level, a much lower current provides a good signal to noise ratio. Principle of Operation Applied Sensing Technologies offers Galvanic type Micro-Fuel cell for sensing oxygen concentration in a gas mixture. These sensors are specific to oxygen and are excellent choice to measure oxygen in a variety of gas mixtures without any significant interference from other gases. These sensors are: - specific to oxygen - linear response to oxygen concentration - relatively small size - disposable at the end of their useful life - exhibit absolute zero - one point calibration - low drift with long operating life - no maintenance Color Coded Ring The sensing element of the sensor, typically silver or gold plated perforated metal, covered by a gas limiting oxygen barrier, senses oxygen concentration in a gas mixture and provides a current signal proportional to the partial pressure of oxygen. To facilitate oxygen reduction reaction at the sensing element, easily oxidizable metal such as Pb serves as the anode (the electron source). The current flows between the anode and the sensing element via an external circuit. The flow of current is measured and expressed in understandable oxygen measuring units. The reduction and oxidation reactions are given as Applied sensing Technologies sensors are color coded for easy identification of sensor application. The SRX series sensors are for O2 measurements in innert gasious hydrocabon and hydrogen; blue color for PPM O2 and green for % O2. In the SRZ series sensors, brown color is for O2 measurements in gases containing any level of CO2 and trace levels of H2S. Sensor signal is usually constant per unit oxygen concentration. However, ambient operationg conditions could affect the sensor signal, thus requiring perioding calibration. As stated, sensor signal is always proportional to the partial pressure of oxygen in a gas mixture, double the partial pressure - double the signal, no oxygen - no signal. This charecteristic of the sensor allows a single point calibration. Percent oxygen sensors could be calibrated in ambient air (20.9% oxygen at ambient pressure). Sensor Calibration

APPLIED SENSING TECHNOLOGIES PPM oxygen sensors could be calibrated in ambient air but this option takes a significant amount of time for the sensor to recover to low PPM level (upwards of 60 minutes), therefore, a span gas containg 8-80 PPM oxygen is recommended for calibrtion. Typical calibration interval is 1-3 months. Temperature Effect Sensor signal is also dependent on ambient temperature, sensor signal increases exponentially with increasing temperature, generally 2.0% to 2.4% per C. While processing sensor signal, a resistor/thermistor network may be used to offset temperature...

APPLIED SENSING TECHNOLOGIES Cross Reference to Oxygen Sensors Industrial PPM Oxygen Sensors AST Part No. Galvanic type electrochemical oxygen sensors, also known as micro-fuel cells, are extremely versatile, very specific to oxygen, easy to use and require no maintenance except a periodic calibration. At the end of their useful life, they can be disposed off just like a battery. These sensors are extensively used in a variety of applications, specifically monitoring sub-PPM levels of oxygen in inert gases, hydrogen and gaseous hydrocarbon streams. Cross reference shown is for reference of...

APPLIED SENSING TECHNOLOGIES Cross Reference to Oxygen Sensors Medical Oxygen Sensors - Ventilators AST Part No. Teledyne R-17MED AII PSR-11-917-J CITY MOX-2 Maxtec MAX-13 CITY Maxtec Teledyne T-7 CITY Maxtec Envitec CITY Maxtec Figaro Maxtec Teledyne R-22MED CITY MOX-1 AII PSR-11-917-M Maxtec MAX-12 SRX-CT Series sensors are specifically designed for breathing air equipments such as ventilators. User must check compatibility of sensors with the intended equipments. NOTE: For optimal accuracy, sensors for ventilators must be calibrated before each use and 24 hours after continuous use in...

APPLIED SENSING TECHNOLOGIES Cross Reference to Oxygen Sensors Diving Oxygen Sensors AST Part No. AST-17D AII Teledyne Maxtec City Teledyne R-33-S, R-33D IT Gambert D-03 Analox 9212-0 UBS O2 Stick AII PSR-11-37-D2-1 IT Gambert D-09 Analox 9121-0 Teledyne R-33S1, R-33D1 SRX-CT and AST series sensors are specifically designed for breathing air analyssis and scuba diving application. User must check their compatibility with intended equipment/rebreather before. Sensor must be calibrated before use and shouldn’t be used after the expiry date. Sensors for rebreather equipment shows linear...

APPLIED SENSING TECHNOLOGIES Cross Reference to Oxygen Sensors Industrial % Oxygen Sensors AST Part No Galvanic type electrochemical oxygen sensors, also known as micro-fuel cells, are extremely versatile, very specific to oxygen, easy to use and require no maintenance except a periodic calibration. At the end of their useful life, they can be disposed off just like a battery. These sensors are extensively used in a variety of applications, specifically monitoring oxygen in air separation, food processing and packaging, area monitor for personal safety, inert gas welding and glove box purge...