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b1 Airflow Sensing Elements
b1 Pressure Sensing Elements
b1 Flow Transducers
b1 Differential Pressure Transducers
b1 Indicating Meters
b1 Calibration Tools
 
 
 
Airflow/Pressure Measurement
 
PCI has designed and manufactured airflow and pressure measurement systems to meet the needs of all commercial and most industrial applications since 1984. PCI airflow and pressure measurement systems are installed worldwide as part of systems requiring continuous signals for HVAC or industrial automatic control, alarming, and process indication. The accuracy of PCI's airflow and pressure measurement systems has been independently qualified in accordance with Figure 7 in the testing procedure of American National Standards Institute/Air Movement and Control Association (ANSI/AMCA) Standard 210-85. However, it is more important to note that the stated accuracy of all PCI devices is constantly being field-validated by independent test and balance firms; their balance reports document conformance to specifications and confirm the superior operating performance of PCI commissioned systems.
The airflow and pressure measurement systems are comprised of primary sensing elements and a transducer or indicating meter. The primary sensing elements provide output signals readily convertible to air velocity, air volume, and differential pressures by the transducer or indicating meter.
 
Primary Sensing Elements
 
All PCI primary sensing elements (Flow Sensing Elements [FE Series] and Pressure Sensing Elements [PE Series]) are multi-point self-averaging devices. The output of the FE Series is differential (velocity) pressure used to indicate airflow quantity at the point of measurement. PE Series output signals are the actual static pressures at the element locations. Unique features include:
 
b2 Economically priced to be a value-added part of every system designed
b2 Field-proven durability and performance
b2 Assured accuracy for the life of the system
b2 Speed-of-sound transmittance of output signals
b2 No calibration required
b2 No correction factor (k) required
b2 Aerodynamic design results in extremely low resistance to airflow with minimal energy loss, operating costs, and maintenance (if any)
b2 Simple, fast, low-cost installation in both new and existing systems
b2 Designed to satisfy a wide variety of application needs
b2 Operates at velocities as low as 100 feet per minute (fpm)
b2 Aluminum construction is standard; Type 316 stainless steel and Type 1 polyvinyl chloride (PVC) are optional
b2 Available in any practical size and configuration
 
Transducers
 
PCI's differential pressure transducers (DPT Series) and flow transducers (FT Series) are "stand-alone" components which can be mounted into a control panel enclosure for an entire system or major subsystem. The DPT Series transducers measure and convert pneumatic input differential pressure signals to an electronic analog output signal linear to differential pressure. The FT Series transducers are similar to the DPT Series except that both total and static pressure inputs are required. The measured difference between the total and static pressure is the velocity pressure. By performing square root extraction and scaling to the velocity pressure signal, the resulting output signal is linear to velocity (fpm) or volume (cfm). The output is an electronic analog signal that can be used by a controller, indicator or data logger. Unique features include:
 
b2 PCI's Ultra Low Differential Pressure Transducer Sensor utilizes a glass-clad silicon chip operating on the capacitance principal. The inherent high sensitivity of a variable capacitance sensor with the repeatability of a micro-machined silicon diaphragm makes it ideal for high accuracy measurement of low differential pressures. The high level output signal, excellent long term stability, and fast dynamic response of PCI's transducers, make them ideal for a wide range of commercial, industrial, laboratory, and aerospace applications.
b2 The Automatic Zeroing Circuit performs a zero calibration of the differential pressure transducer output at user-selected intervals. Uninterrupted control and/or indication is maintained at the last output value during the approximately five second calibration period. The transducer resumes its real-time analog output response after zero calibration is complete.
b2 The Signal Scaling Circuit converts the differential pressure signal (static pressure or velocity pressure converted to velocity in fpm or airflow in cfm) to a user-specified full scale value.
b2 The Process Display shows the converted transducer output signal for local monitoring capability.
b2 The Square Root Extractor Circuits are used in all flow transducers to conform the output to the square root curve of velocity vs. velocity pressure. This circuit is essential for signal accuracy when the output is made linear to velocity or airflow.
b2 The Analog Meter is a diaphragm-actuated differential pressure gage directly connected through bulkhead fittings and tubing to the static pressure or airflow measuring element. This provides a continuous and direct indication of the true measured value independent of the hydraulics or electronics of other control components, and thus provides an instant visual check on the system status. The meter is provided with either a dual scale (fpm and cfm) for airflow readings or a single scale (inches of water column) for pressure readings. The indicating scales may also be customized for a specific design need.
 
Indicating Meters
 
PCI flow indicating meters (FI Series) are available for use with FE and PE Series sensing elements for process indication where automatic control is not required or where local indication is specified. Unique features include:
 
b2 The Analog Meter is a diaphragm-actuated differential pressure gage directly connected through bulkhead fittings and tubing to the static pressure or airflow measuring element. This provides a continuous and direct indication of the true measured value independent of the hydraulics or electronics of other control components, and thus provides an instant visual check on the system status. The meter is provided with either a dual scale (fpm and cfm) for airflow readings or a single scale (inches of water column) for pressure readings. The indicating scales may also be customized for a specific design need.
b2 Multiple Analog Meters are two or more analog meters as described above.
b2 Surface-mounted Steel Enclosures are used for multiple analog meter applications. They are constructed of 16 gage (ga.) steel to NEMA 12 specifications and are coated inside and out with gray color textured powder paint. Pressure connections are convenient bulkhead compression fittings suitable for 1/4 inch OD metallic or thermoplastic tubing.
b2 Surface-mounted Brushed Aluminum Enclosures are made of 16 ga. material and have no NEMA rating. Pressure connections are convenient bulkhead compression fittings suitable for 1/4 inch OD metallic or thermoplastic tubing.
 
 
 
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Theory of Operation
 
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Airflow Measurement Accuracy