The Art of Practical and Precise Strain Based ... - Webprofile.info

More documents

Recommendations

Info

Strain-Based Measurement Introduction:Applications Note 1-13:The Diaphragm Strain-Gaged Pressure SensorThe general reference to the strain-gaged diaphragm pressure sensor refers toany sensor where the strain gages are directly bonded to, or are an intrinsic partof the diaphragm spring member of the sensor, and where pressure-inducedbending of the diaphragm produces strains within the diaphragm to which thestrain gages respond producing output. The bending diaphragm sensor structurepossesses zones of both tension and compression strains that are straingagedto produce the sensor output. The derivation of both radial and tangentialstrain components for the flat, circular, uniform-thickness, and fixedperimeterdiaphragm are provided.General Discussion:Recessed DiaphragmsFIGURE 1-46. The Recessed Diaphragm:Diaphragm strain-gaged pressure sensors fall into two general categories.The first is the recessed-diaphragm design shown as Figure 1-46,where the sensing diaphragm is recessed within the mounting port ofCHAPTER 1-80 The Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999
Applications Note 1-13:the sensor. The significant dead volume produced by recessing of the sensordiaphragm severely limits the frequency response of such a sensor. Thecavity over the diaphragm will act as a Helmholtz cavity or pneumatic filter,attenuating dynamic pressure inputs significantly. The recessed-diaphragmdesign provides superior mechanical protection of the sensingdiaphragm and generally superior zero stability as the cavity will also addsignificant thermal mass to the sensor, rendering the design less sensitive tothermal-transient inputs. The added structural mass of this design also providesexcellent spring member support with the diaphragm removed fromthe generally high stresses found in threaded-mounting configurations. Inmeasurement environments where compacting particles could be present,the recessed-diaphragm design may not be the most suitable, as compactionof particles over the sensor diaphragm (Figure 1-47) will reduce thesensitivity of the sensor significantly. In cleaning of the pressure port anddiaphragm, only fluid cleaning solvents and solutions compatible with thewetted materials of the sensor should be used. The use of any mechanicalcleaning tools will undoubtedly result in damage to the sensor.FIGURE 1-47. Particulate Compaction (Recessed-Diaphragm):Compacted ParticlesParticulate-Laden FlowMany other variations of the recessed diaphragm design are commonlyavailable with many process-type designs being of the filled variety wherethe active sensor is isolated from the measurand (medium) by a flexibleThe Art of Practical and Precise Strain Based Measurement 2nd Edition © 1999 CHAPTER 1-81
Page 1 and 2:
The Art of Practical andPrecise Str
Page 3 and 4:
Special Credits:Mrs. Helen Pierson,
Page 5 and 6:
Table of ContentsBy James G. Pierso
Page 8 and 9:
ContentsApplications Note 4-10:Lead
Page 10:
ContentsCHAPTER 8Electrical Conside
Page 13 and 14:
CHAPTER 1Strain-BasedMeasurementInt
Page 15 and 16:
Applications Note 1-1: Introduction
Page 17 and 18:
Applications Note 1-1: Introduction
Page 19 and 20:
Applications Note 1-2:The Art of Ap
Page 21 and 22:
Applications Note 1-31. The presenc
Page 23 and 24:
Applications Note 1-3result in a pe
Page 25 and 26:
Applications Note 1-4:The measureme
Page 27 and 28:
Applications Note 1-4:uncertainty i
Page 29 and 30:
Applications Note 1-5:All strain-ba
Page 31 and 32:
Applications Note 1-6:Applications
Page 33 and 34:
Applications Note 1-6:ical size of
Page 35 and 36:
Applications Note 1-6:and where:j i
Page 37 and 38:
Applications Note 1-6:5. millivolts
Page 39:
Applications Note 1-6:.Electrodynam
Page 44 and 45: Strain-Based Measurement Introducti
Page 104: Strain-Based Measurement Introducti
show all

The Art of Practical and Precise Strain Based ... - Webprofile.info

Create successful ePaper yourself

Delete template?

Save as template?