Flow sensors find various uses in the Building Automation systems. One of the increasingly more common uses of flow sensors is to measure the chilled water, heating water, and electrical energy consumption of a building or a tenant. Sometimes it is used to verify energy consumption and utility costs. Measuring water energy consumption requires temperature and flow measurements. In the following application, a flow meter is used to measure the liquid flow through the pipes. Flow sensors are also often utilized to measure air velocity indoors. This provides for a controlled ventilation of living areas as well as an optimization of energy costs. Flow sensors are also employed in water and wastewater management. Measurement of water, wastewater, and gray water used by a building provides an understanding of the building’s carbon footprint.
There are various types of flow sensors for HVAC systems available on the market today. In order to make an appropriate selection of a flow sensor, it is important to have a clear understanding of the requirements of a particular application. Characteristics that should be considered: familiarity of the staff with the type of product and its calibration procedure, maintenance, type of fluid, characteristics of the fluid, minimum and maximum pressure and temperature values and etc. Figure below illustrates different types of flow sensors:
Differential pressure flow meters are possibly the most commonly used type. The calculation of fluid flow is performed by reading the pressure loss across a pipe restriction. As a fluid passes through, it accelerates, and the energy associated with this acceleration is obtained. The pressure differential head is measured. Different types of differential pressure flow meters:
Additionally, Jalpesh has shown various very detailed diagrams of differential flow meters in his blog post.
Maria has decided to focus on fluidic flow measurement sensors. These are much more advanced than the basic differential flow meters I have described. It also sees as though they are more applicable for applications with gaseous fluids.
http://www.omega.com/literature/transactions/volume4/T9904-07-DIFF.html#diff_1
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