Pressure Transducer Articles on Environmental XPRT

Effects of Arching on Response Time of Miniature Pore Pressure Transducer in Clay

A study of the response time of miniature pore pressure transducers embedded in clay soils is presented. The highly nonuniform pore pressure distributions around the transducers due to arching and stress concentration can have a significant effect on transducer response especially when the surrounding soil is loaded anisotropically. This is caused by the difference in compressibility of the soil ...

Sep. 1, 1990

By ASTM International

Frequency Response of Diaphragm Pore Pressure Transducers in Dynamic Centrifuge Model Tests

A theoretical relation for estimating the frequency response of diaphragm pore pressure transducers is derived by considering the interaction between the diaphragm, porous cap, air, and pore fluid inside the transducer. Using this relation, the frequency response of a pore pressure transducer under several centrifuge modeling environments is studied. The results indicate that the viscous drag ...

Sep. 1, 1990

By ASTM International

Pressure transmitters: It’s class that counts

KELLER would like to do away with DIN standards. The company is backing the introduction of an accuracy class, as it did for pressure gauges. The conditions under which the class is complied with are described in specifications. The new EC standards make it more difficult for companies to manufacture their own transmitter electronics. Changing from OEM transducers to OEM transmitters is ...

Aug. 1, 2008

By KELLER AG für Druckmesstechnik

Water Pressure Measurement with Time Domain Reflectometry Cables

Attributes of the remote measurement of piezometric water pressure and water level with time domain reflectometry (TDR) techniques are investigated. The evaluation includes a two-wire system for unusually small riser tubes as well as parallel wire and air-filled or hollow coaxial cable for typical installations. Comparison of TDR cable and commercial pressure transducer technology shows coaxial ...

Mar. 1, 1996

By ASTM International

Differential Pressure and Temperature Monitoring in a Hospital Cleanroom

Accsense A1-01a Wireless Environmental Data Loggers CHESTERLAND OH—April 9, 2012 CAS DataLoggers recently provided the wireless pressure and temperature monitoring solution for a hospital maintaining a surgery cleanroom to protect patients from a variety of environmental contaminants. Staff entered and exited through airlocks and were required to wear cleanroom suits before entering. Air ...

Apr. 10, 2012

By CAS DATALOGGERS

Automatic Volume Change and Pressure Measurement Devices for Triaxial Testing of Soils

Desirable requirements for volume capacity and precision of volume change devices for triaxial testing are studied, and operational requirements for devices suitable for automatic datalogging are reviewed. Two devices that fulfill these requirements have been constructed by the writer by combining existing design principles. One device consists of a buret system with differential pressure ...

Dec. 1, 1988

By ASTM International

Advantages of Midheight Pore Pressure Measurements in Undrained Triaxial Testing

Most soil mechanics laboratories still prefer the use of rough end platens during triaxial testing despite an awareness that nonuniform stress conditions occur within the soil specimen. This practice may to some extent be due to a lack of awareness of the magnitude of inaccuracies which may result. This paper describes results from unconsolidated undrained triaxial compression and extension tests ...

Jun. 1, 1991

By ASTM International

Design and Performance of the Imperial College Instrumented Pile

This paper describes the design, calibration, and field performance of a number of new instruments that have been used for research into the behavior of displacement piles in clays and sand. The instruments include axial load cells, surface stress transducers, and pore pressure probes. The special features of the surface stress transducers and pore pressure probes are described in detail, and ...

Dec. 1, 1991

By ASTM International

A Self-Boring Pressuremeter System

The paper describes some of the development work on the Cambridge University version of the self-boring pressuremeter (the so-called “Camkometer”), which has been carried out at the University of Western Australia over a number of years. This work included improvement of the pore-pressure measuring system and development of a deairing system for the pore-pressure transducers, new supply-voltage ...

Sep. 1, 1988

By ASTM International

A Multi-Sensor Piezometer for Shallow Marine Sediments in Coastal Environments

A multi-sensor piezometer has been developed to measure dynamic excess and ambient pore pressures in shallow marine sediments under the effect of surface waves, tides, and currents. The probe consists of a shaft (1.5 m long with five porous stones at subseafloor depths ranging from 0.10 to 0.93 m) and two upper chambers (one that is hermetically sealed for the transducer electronics and another ...

Dec. 1, 1996

By ASTM International

Two Technologies for Flow Measurement from Outside a Pipe

Doppler and Transit Time are two very popular types of flow meter for non-invasive measurement of flow in full pipes. We tend to confuse these technologies because they are both ultrasonic and both measure flow by using sensors clamped onto the outside of a pipe. In the real world they actually work best in opposite applications. Success in your installation depends on understanding the ...

Jul. 31, 2012

By Greyline Instruments Inc.

Determination of Consolidation Properties for Very Soft Clay

A finite strain consolidation test with a constant surcharge to determine the compressibility (e - s') and permeability (e - k) relationships of very soft clay is proposed. The method uses Gammarays and pore pressure transducers to measure density and pore pressure profiles, respectively, at various times of the test without hindering the consolidation process. The constant surcharge applied ...

Dec. 1, 1988

By ASTM International

Sonic Thermometry

Sonic anemometers have had extensive use in the scientific community. These instruments are used to measure atmospheric parameters that most rotating instruments cannot. Wind speed and wind direction or individual axes of wind velocity are most commonly measured. Along with these measurements, another parameter can be extracted from the sonic anemometer (i.e.), sonic temperature. Since the ...

Sep. 1, 2012

By Applied Technologies, Inc. (ATI)

A New Simple Shear Apparatus

A new simple shear device capable of measuring a complete set of stresses during simple shear deformation is described. This simple shear device tests a cuboidal specimen whose lateral sides are surrounded by a rubber membrane reinforced by a stack of Teflon® coated aluminum plates. One of the aluminum plates is used as a transducer to determine the lateral stresses on planes normal and parallel ...

Dec. 1, 1988

By ASTM International

Steady monitoring of potable water in storage tanks case study

MonoScan L provides Taiwan Water Supply Corp. a dependable ultrasonic solution for measuring potable water level in their storage tanks. Taiwan Water Supply Corp. supplies water treatment services for the city of Taichung, Taiwan. Part of the process includes storage tanks of potable water that are conveyed directly to the city's water system. The problems The company used ...

Aug. 1, 2003

By Solid Applied Technologies Ltd. (SolidAT)

Tensiometers—Theory, Construction, and Use

Standard tensiometers are used to measure matric potential as low as -870 cm of water in the unsaturated zone by creating a saturated hydraulic link between the soil water and a pressure sensor. The direction and, in some cases, quantity of water flux can be determined using multiple installations.A variety of commercial and fabricated tensiometers are commonly used. Saturated porous ceramic ...

Mar. 1, 1992

By ASTM International

A Modified Commercial Triaxial Testing System for Small Strain Measurements: Preliminary Results on Pisa Clay

measuring accuracy of soil stiffness at small strains, (2) a reliable automatic procedure for K0 consolidation, and (3) a minimum disturbance during system saturation and specimen consolidation. To obtain the above objectives, many modifications were introduced. The cell structure and loading piston were modified and many transducers were introduced, including the LDTs for local radial and axial ...

Mar. 1, 1995

By ASTM International

External Measurement of Axial Strain in the Triaxial Test

The errors involved in measuring axial strains in the triaxial test are reviewed based on previously published results. A technique is described to allow more reliable external measurements to be obtained and used for strain calculations. The technique is simple, inexpensive, and can be implemented in any soils laboratory. Comparisons are made between the strains obtained by this method and those ...

Jun. 1, 1995

By ASTM International

Some Factors Affecting In Situ Measurement Using the Cambridge Self-Boring Pressuremeter

Research presented in this paper was conducted to assess the influence of environmental and physical factors on measurements made with the self-boring pressuremeter (SBPM). It was found that temperature changes during deployment and long-term instrument calibration drift can result in misinterpretation of in situ soil properties. It was also observed that neglecting to consider the sequential ...

Jun. 1, 1993

By ASTM International

Brüel & Kjær accelerometers - 65 years of excellence

The Thirties Already before the two young engineers Per V. Brüel and Viggo Kjær graduated as Masters of Electrical Engineering in 1939, they had decided to start a company together. However, they felt it was necessary to learn more and get some practical experience before actually going ahead, so P.V. Brüel became assistant to professor P.O. Pedersen in the newly created ...

Sep. 1, 2010

By Brüel & Kjær Sound & Vibration Measurement A/S

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