LOA-105 Optical Anemometer for Aluminum Plants is specially designed for superior performance in tough pot room environments. The sensor uses proven optical technology to measure the airflow velocity through the roof vents. The eye-safe LED transmitter and twin photodiode receiver are placed at either end of the pot room and simply need to "look" through the HF flow to measure the airflow. Its maximum path length of 3 km allows the LOA to handle the biggest of pot room's easily. The instrument is ready with features such as HF resistant windows and air knives to keep the windows clear. LOA has automatic gain control and continuous self-checking.

The optical technology of the LOA has multiple advantages:

• Complete Path-Averaged Measurement - The LOA takes the average velocity rate over the entire optical path. This results in a more representative measurement of the flow - much better than point- source sensors.
• Predictable Performance Designed for long-term use in a pot room, all critical components of the LOA are enclosed in air-purged housings and HF resistant windows are used to transmit the IR light into the pot room environment.
• Low Maintenance As simple as periodic cleaning and checking alignment.

The LOA-105 has received the seal of approval from the US government with EPA Method 14 Equivalency Approval (the rule for measuring airflow velocity in aluminum roof vents. LOA-105 has captured nearly 70% of the US market. Major players in the industry such as ALCOA, Reynolds and Kaiser use LOA as well as ALCAN in Canada, Comalco in Australia, and ALCOA Europe.

LOA design, based on decades of experience in harsh environments, results in a rugged, extremely reliable sensor, immune from typical error modes. LOA uses AGC circuitry to eliminate the effects of output power drop, contaminated optics, or dusty air. Internal diagnostics alert the user if signal strength gets too low for normal operation. Preventative maintenance, suggested every 6 months, is as simple as cleaning the windows and verifying optical aim. With DSP based design, no field calibration is ever needed.

Understanding the Fence-line

LOA Long-baseline Optical Anemometer

LOA technology was developed by ERL/NOAA (Environmental Research Labs / National Oceanographic and Atmospheric Administration) in the 1970’s.  LOA technology was developed to simultaneously measure the average wind across the optical beam (crosswind) and the atmospheric turbulence (CN2) over the measurement path.  

Open Path Averaged wind sensors like LOA-005 offer a more spatially representative measurement compared to using a single point wind sensor measurement for large area wind studies.  LOA can provide Space averaged 2-dimensional wind measurements, which are more representative of the average wind than a few instruments in situ can be.  A single path LOA measures crosswind (wind speed averaged along the path and relative to the direction that it is blowing across the path. When you put a second LOA path up at an angle near 90 degree  to the first LOA path, you can use simple math to calculate not only the wind speed but also the wind vector based on the ratio of the one path to the other. 

Understanding the movement of air over a large area of concern is possible when you set up multiple LOA’s to form an enclosed contour.  At each lag, LOA will measure the crosswind along the optical path.  By averaging the wind vectors on all sides, LOA technology can give the average 2-dimensional wind over a large area.   Also, by measuring the convergence or divergence of all the winds measured at all the lags, LOA can give the near-ground vertical wind of the enclosed area!

LOA Set Up

•        Portable sets up on special mounts and tripods

•        Powered by AC or DC (car battery) supply.

•        Sensors can be placed in safe areas away from hazards.

•        Completely Eye Safe (can operate in public areas)

•        Shoot LOA beams from on top of buildings, out windows or over water

Features & Benefits:

•        A single LOA measures bi-directional cross winds up to 10 km

•        Set up Two LOA’s in an x pattern and that will give you both the east-west wind component  and north-south wind component  so you can measure the magnitude and wind direction of the wind vectors over a large area.

•        Three LOA’s can form a triangle around the area of concern and account for the movement of the air in that large space.

•        Combine LOA with other sensors to better understand the mass movement of hazardous wind.  LOA technology measures true cross wind averaged along the optical path.

•        LOA technology can accurately measure the space averaged 2-dimensional wind velocities over a large area.

•        Sensors can be placed outside of hazardous areas for safety.

Successful Applications.

Aluminum Smelters

LOA-105 received method 14 approval to measure the roof vents of aluminum smelter pot rooms.  The advantage is the sensors can be place in areas outside the hazardous HF gas.

·       Spatially Averaged Measurement – The LOA-105 takes the average velocity rate over the entire optical path. Due to flow variations, this result provides a more representative measurement of the flow characteristics in a pot room unlike point-source sensors.

·       Predictable Performance over Time – Designed for long-term use in a pot room, all critical components of the LOA are enclosed in air-purged housings and HF resistant windows are used to transmit the IR light into the pot room environment.

·       Low Maintenance – Preventative maintenance is as simple as checking optical alignment and performing a calibration check using the TST-104. Since it is not directly exposed to the effluent, the LOA has better durability over instruments that are directly exposed to HF flow.

·       The LOA-105 has received the seal of approval from the US government with EPA Method 14 Equivalency Approval (the rule for measuring airflow velocity in aluminum roof vents).

Osi Per EPA approval letter

LOA sensor designed to NOAA TM ERL WPL-52

LOA calibrator designed to NOAA TM ERL WPL-88

Continuous self test for light level and other parameters

HF resistant polycarbonate windows

Air purged housings

Air knife built into Pneumatic & Alignment Apparatus

Thanks and Regards,