Pressure and volume flow of pipes and rooms must be accurately monitored for heating, ventilation and air conditioning systems to function in an energy-efficient and cost-effective manner. This requires sensors with the smallest of measuring ranges and higher measuring sensitivities, accuracies and long-term stability. Ideally, pressure sensors should be compact and easy to assimilate into OEM systems.
Volume Flow Measurement
Pressure sensors are designed to measure the pressure drop across a flow element as a degree of the volume flow. In volume flow controllers for variable volume flow (VAV), the pressure value is used to regulate the damper position within a closed control loop, permitting demand-based ventilation. Crucial for the quality of the control, pressure sensors are a vital component of these systems.
Channel Pressure Monitoring
When flaps inside a ventilation duct open and close, the pressure of the adjoining room changes accordingly. Using a pressure sensor, efficient ventilation and air conditioning can be accomplished via regulation of the fan that ensures constant duct pressure. By monitoring the duct pressure and controlling the fan power, pressure sensors produce a system that is highly safe and efficient.
Room Pressure Monitoring
In air-conditioned rooms, pressure differences between individual regions or between a room and the environment are lessened by regulating the supply and exhaust air. In cleanrooms, on the other hand, overpressure must be maintained to prevent the entrance of air that is unclean. Conversely, laboratories and hospitals utilize negative pressures to avoid the spread of germs and toxic matter. Across all such applications, pressure differences are monitored using highly precise pressure sensors, thus guaranteeing safety and comfort.
When filters become dirty, ventilation ducts decrease in pressure and subsequently require a higher level of fan power, raising energy costs. An electronic filter monitor with combined differential pressure sensor can detect the decrease in ventilation pressure and triggers a notification to change the filter. In addition to aiding the cost-effective operation of ventilation and air conditioning systems, pressure monitoring using sensors can also detect system faults such as a cracked filter.
Sensor Solutions for Air Conditioning
First Sensor is a leading manufacturer of platform-based pressure sensors and aims to provide sensor solutions for any application-specific requirement. First Sensor offers their sensor technologies, which measure the smallest differential pressures in air-conditioning. Examples include flow-based differential pressure sensors and membrane-based piezo-resistive silicon pressure sensors.
Flow-based LDE pressure sensors measure thermal mass flow of air that is passed through a very small sensor integrated into the flow channel. Very low pressures can be measured using this unique sensor technology, with maximum resolution, high sensitivity and offset stability. In addition, these pressure sensors are immune to the effects of dust or moisture, a great benefit in comparison to conventional flow-based pressure sensors.
First Sensor offers two series of membrane-based piezo-resistive pressure sensors; HCL and HCLA. These pressure sensors provide excellent offset stability and position insensitivity through a unique internal compensation system. Silicon-based MEMS sensors by First Sensor show good linear signal-pressure characteristics ranging from 2.5 mbar full-scale value and offer analog and digital interfaces.
This information has been sourced, reviewed and adapted from materials provided by First Sensor AG.
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