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Q45D Dissolved Oxygen Monitor

 

Improve Performance & Reduce Maintenance Costs!

Dissolved Oxygen water quality monitoring is critical for aeration system process control. Optimization of the biological process, whether it’s removal of organic material, nitrification, or nitrification/denitrification, depends on maintaining proper D.O. levels. Controlling air flow to within the optimal range eliminates excess aeration, which translates into significant energy savings.
 
ATI’s Model Q45D Dissolved Oxygen Monitor is designed to provide reliable oxygen measurement and help reduce operating costs. Two types of sensing technologies are available for use with the Q45D system: Membraned Electrochemical and Optical (fluorescence). Both sensors will provide reliable long-term performance with minimal maintenance. No hardware modifications are required to change from one sensor type to the other. The monitor can be configured for AC or a portable battery-powered unit to meet a variety of monitoring needs.
 
AUTOMATIC SENSOR CLEANING!
A Blast of Air Keeps the Auto-Clean Sensor Clean!
 
ATI’s provides the ideal answer for automatic Dissolved Oxygen sensor cleaning.  Employing a unique “air-blast” cleaning method, sensors can be cleaned as often as necessary without operator attention.  Pulses of pressurized air delivered through a nozzle at the tip of the sensor remove accumulated solids from critical sensing surfaces, resulting in accurate and reliable measurements.
 

Optical Sensor Reduces Maintenance!

 

ATI DISSOLVED OXYGEN SENSOR TYPES

- OPTICAL SENSOR

The optical DO sensor operates on a light-based principle called “fluorescence” which is a type of luminescence. Certain chemical compounds will absorb one type of light energy, and then emit a different type of light energy. This light emission is called luminescence.
 
The active portion of the sensor has a metal-based compound embedded in a structural matrix. A light source inside the sensor illuminates this compound which absorbs light at a specific wavelength. The compound then emits light at a different wavelength which is picked up by a photo detector within the sensor. As oxygen diffuses into the active sensor material it interacts with the light absorbing compound and interferes with the emission reaction. This interaction, called quenching, causes the light absorbing material to release energy in a form other than light. The degree of quenching is proportional to the concentration of dissolved oxygen. The quenching reaction is reversible, which allows this sensor to measure increasing and decreasing concentrations of oxygen.
 
Optical sensors do not have internal electrolyte, so maintenance of this type of sensor is limited to changing the optical element. Over time, the element will lose the ability to absorb light due to a process called “bleaching”. With some sensors, this process is greatly accelerated when it is exposed to direct sunlight, and will cause irreversible damage to the sensor element.
 
ATI’s optical sensor element is designed to last a several years in normal operation. The sensor design allows for exposure to direct sunlight without damaging the sensor element.
 

- GALVANIC MEMBRANED SENSOR

Membraned type D.O. sensors have been used for D.O. monitoring and control for over 40 years and have proven to be consistently accurate and reliable. Properly designed, a membraned sensor will provide continuous service for a year or more without maintenance of any kind.
 
Galvanic oxygen sensors function in much the same way as a battery. The sensing elements consist of platinum cathode and lead anode, with a durable Teflon membrane isolating the sensor system from the liquid being measured.
 
Oxygen diffuses through the membrane and is reduced to hydroxide ion on the surface of the cathode. This reaction generates current between the platinum and lead electrodes which is proportional to oxygen concentration. An RTD temperature element measures water temperature and corrects the sensor signal for its effect. The result is a D.O. measurement that’s accurate over an operating range of -5-50°C.
 

PRODUCT FEATURES

Sensor Options

Choice of using either optical or galvanic membraned sensors. Electronics handle either sensor option without adjustments or special programming.
 

Auto-Cleaning

Automatic “Air Blast” sensor cleaning system available for reducing maintenance in applications where sensor fouling is a problem.
 

AC Power Options

Power options include 115/230 VAC.
 

Analog Output Options

Two isolated 4-20 mA outputs are standard. Default setting provides analog outputs for D.O. and temperature.
 

PID Output

Standard PID control function assignable to one analog output.
 

Relay Contacts

Two SPDT relays are standard, with relay functions programmable for alarm, control, or trouble indication.
 

Flexible Mounting

NEMA 4X (IP-66) enclosure is suitable for wall, pipe, or panel mounting.
 

Clear Display

Back-lit large LCD display provides clear visibility in any lighting conditions. A scrolling second line on the display provides additional information and programming prompts.