A Computer-Controlled Pressure Standard

1999 ◽  
Vol 121 (1) ◽  
pp. 210-212
Author(s):  
Othon K. Rediniotis
Keyword(s):  
Pressure Transducer ◽  
Pressure Range ◽  
High Accuracy ◽  
Wind Tunnel Testing ◽  
Dual Use ◽  
Pressure Source ◽  
Subsonic Wind Tunnel ◽  
Pressure Standard ◽  
Computer Controlled ◽  
Transducer Calibration

The operating principles, as well as the technical aspects of the implementation of a new computer-controlled pressure standard are presented. The instrument can have dual use: either as a pressure source or as a pressure sensor. The device is intended mostly for use in problems where small differential pressures are of interest, i. e., 0–2.5 KPa and high accuracy is desired. Such a pressure range encompasses, for example, most of the pressure measurement applications in subsonic wind-tunnel testing. The device interfaces to a PC and is ideal for fully-automated pressure transducer calibration applications. The accuracy of the pressures produced or measured by the device is 0.08 percent F. S. (Full Scale).

High-precision in situ measurement of speed of sound in hydraulic systems

2019 ◽  
Vol 234 (3) ◽  
pp. 299-313
Author(s):  
Nigel Johnston
Keyword(s):  
High Precision ◽  
Speed Of Sound ◽  
Pressure Transducer ◽  
In Situ Measurement ◽  
Frequency Domain Method ◽  
Hydraulic Systems ◽  
Mean Flow ◽  
Transducer Calibration ◽  
Mean Flow Velocity

An existing ISO standard frequency-domain method for measurement of speed of sound in a hydraulic pipeline is enhanced and extended in this article to include in situ measurement of pressure transducer calibration factors. Transducer mounting stresses are shown to cause variations in the calibration factors, and the proposed method can be used to eliminate these uncertainties, consequently improving the accuracy of the speed of sound. 95% confidence ranges in the speed of sound of less than ±0.1% have been achieved, and such high precision cannot be achieved by other practical methods. The method can also been extended to estimate viscosity and mean flow velocity, but accuracy is less good. Novel time-domain versions of the method are introduced. These may be valuable for real-time monitoring, and changes in speed of sound or calibration factor can be tracked with minimal delay. Some examples showing the effect of sudden aeration are presented; a sudden drop in speed of sound is apparent.

An AD7746-Based Data Acquisition System for Capacitive Pressure Sensor in Weather Detection Application

2011 ◽  
Vol 483 ◽  
pp. 461-464 ◽  
Author(s):  
Zhen Huang ◽  
Jian Zhu ◽  
Le Lu
Keyword(s):  
Data Acquisition ◽  
Pressure Sensor ◽  
Pressure Range ◽  
Data Acquisition System ◽  
High Accuracy ◽  
Acquisition System ◽  
Capacitive Pressure Sensor ◽  
Lcd Display ◽  
Wireless Module ◽  
Weather Observation

Data acquisition system for barometric capacitive pressure sensor with high accuracy is present. The precision of the data acquisition system is less than 1fF, which improves the pressure sensor with high accuracy of 0.1hPa in the pressure range from 5hPa to 1080hPa. The data acquisition system consists of an AD7746 chip, an ATmega16 microprocessor, a 1602 LCD display and a pair of wireless modules. The capacitance data acquired by the AD7746 are transferred to a host computer using RS232 port via wireless module and display on the LCD in real-time. Preliminary results obtained from experiments show that this system fulfills the requirements of the weather observation and can be used in upper-air weather detection applications.

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