Side Wall Sensing for Face Velocity Control

November 10, 2022 | Posted By: Degree Controls Inc.

Do you need to control and monitor fume hood face velocity?

The Degree Controls side wall sensor is a flow-through device used by Laboratory Managers to control and monitor fume hood face velocity. It is typically mounted in the side wall of a fume hood and draws in clean, ambient air, rather than contaminated exhaust air, to measure airflow. Analog and digital output choices are available to provide measured velocity values to fume hood face velocity controllers in real time.

Side wall sensors are configured to order with choices for supply voltage, air velocity profile (30 fpm to 4,000 fpm), analog signals, and UART or I2C communication. Because it pulls clean air from the outside of the hood to the inside, the side wall sensor is unaffected by fume hood contaminants and chemical laden exhaust flows which can compromise the performance of probe-style sensors. Additionally, side wall sensing accounts for sash plane obstructions and other air entrance points, unlike systems which use sash height only to control face velocity.

Side Wall Sensing

The relationship between the side wall sensor’s measured velocity and fume hood face velocity is established with correlation. This only needs to be done once in a given system and is part of the normal commissioning and certification process. The correlation is typically accomplished by using a hand-held °C Point anemometer to measure face velocity and then inputting those readings directly into an airflow monitor. The side wall sensor’s measured velocity exhibits an excellent correlation to face velocity.

The Degree Controls Side Wall Sensor is the most versatile side wall sensing device on the market. It measures actual air velocity and also gives facilities owners and engineers choices to meet the requirements of their applications. For users who wish to implement side wall sensing along with automatic sash control, the Rooster™ Monitor200 airflow alarm and monitor supports both.

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