Differential Pressure technology is commonly used to measure fluid velocity due to their well-defined relationship. The square root of the differential pressure is proportional to the flow rate velocity of the fluid. In ducted systems the total pressure consists of the velocity pressure and static pressure. Velocity pressure cannot be measured directly; it must be derived. By measuring the total and static pressures in a duct, the velocity pressure can be obtained by subtracting static pressure from total pressure. This is achieved in practice by directly measuring the differential pressure between the two.
The job of a transmitter is to receive a signal and transmit it to a recipient. If the recipient is lucky, the signal will arrive exactly as it was transmitted allowing the controller, if there is one, to do its job properly. Depending on your application, high accuracy may or may not be important to you. In the HVAC world, transmitter accuracy is of the upmost importance, not only because you are dealing with the air people breathe, but also because you are responsible for maintaining building health. Make sure you choose the right transmitter and/or controller for your application.
Controlling the amount of outside air entering a building is required to maintain pressurization, meet energy efficiency goals, confirm compliance with local building codes and maintain the health of the building and its occupants. Accurate measurement of outside airflow is required for proper operation of today’s high-performance buildings. Outside air can pose a significant challenge regarding the metering technology to be selected. Some of the more common challenges associated with outdoor airflow measurement include: low airflow velocities over large operating ranges such as a split – min/max economizer system, blowing dust and debris, and moisture laden air at the point of measurement. Choosing a technology that is impervious to airborne contaminants, can measure low airflow rates, has high turn down capability and one that provides the desired BAS outputs will facilitate a successful installation.
This is essential for managing indoor air quality, energy savings and occupant comfort. Prevents unintended pressure levels which can lead to complications for the building systems, the building envelope, and problems between adjacent spaces such as laboratories and hospital rooms.
Thermal Dispersion technology is based on the principle that the amount of heat absorbed by a fluid is proportional to its mass flow. Thermal dispersion (mass) flow measurements are achieved by using two temperature sensors and a heat source located in a flow stream. By measuring the energy (heat) added to the flow stream and measuring the corresponding temperature change, mass flow can be derived. Thermal dispersion is a highly reliable and robust method for accurately measuring airflow velocities in today’s HVAC applications.