wetted parts of pressure sensors

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Wetted Parts of pressure sensors denition and overview

November 25, 2014 | by Eugen Gassmann| Article,Knowledge| No Comments

The term wetted parts is used in connection with pressure sensors for a those parts,

surfaces and!or components that are "potentiay# e$posed to or in direct contact with the

medium under pressure%

&n case of a typica pressure sensor this is mainy imited to those parts of the pressure

sensor caed process connection or pressure port, i%e% the parts via which the pressure

sensor actuay connects to the process% Typicay in the '( this is a standard thread i)e

* N+T, N+T or -*, - 1!2 "mae or femae#%

&t is important to notice that it not ony comprises the materias used in the construction ofthe device but aso e$tends to any seas or .as)ets that are re/uired for the particuar

thread in /uestions i)e +Ttape for conica threads or 3rin.s for cyindrica threads a

sma but important detai that is often overoo)ed%

urthermore the term wetted parts aso incudes any interna seas, weds or membranes!

diaphra.ms of the pressure sensor that are "at east partiay# in contact with the media

used%

Typicay wetted parts of pressure sensors are from four cate.ories

Ferrous materials (lie car!on steel" stainless steel etc#$ mainy used for main

bodies! housin.s of sensors and threads etc%

The ma6ority of pressure ports and process connections on industria pressure sensors are

nowadays made from stainess stee and thin7m sensors mainy use stee as the base

materia for the sensor body but the term can be miseadin. as it seems to impy universa
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corrosion resistance, which is not the case% 8ways chec) for the speci7c .rade of stainess

stee and chec) corrosion resistance and chemica compatibiity carefuy%

Non%ferrous materials (lie Copper" &rass" Gold" 'astello" Elgilo" )itanium etc#$

typicay used as metaic seain.s or in specia desi.ns for sensor bodies, membranes, or ondiaphra.ms as coatin.s%

&n more economica appications, brass is sti a materia common for vaves and 7ttin.s and

therefore is aso used to buid pressure sensors% or specia appications sometimes the use

of titanium or speciaty aoys "i)e .ioy, 9asteoy, or &ncone# is re/uired to provide hi.h

corrosion resistance or superior measurement performance% (ome eements "i)e -od# are

sometimes used to coat membranes and diaphra.ms as a protection a.ainst corrosion and

chemica attac) or to prevent 9ydro.en to pass throu.h% The cost of some of those materias

and! or the di:cut handin. and machinin. can be prohibitive in certain appications%

Elastomers and Plastics (lie PA" *iton" P)FE etc#$ typicay used as .as)ets, seas or

coatin.s for diaphra.ms

+astics and astomers are used mainy for 3rin.s or as .as)ets and seas, (peciaty

pastics i)e +T are sometimes used as a protective coatin. for membranes and

diaphra.ms%

Ceramics (lie A+,-.$ typicay used as a sensor body! diaphra.m for capacitive or

thic)7m resistive pressure sensors

The use of ceramics as a sensor materia promises hi.h chemica compatibiity and

temperature stabiity that is unfortunatey /uite often compromised because ceramicscannot be hermeticay seaed by wedin. but aways re/uires the use of "soft# seain.

materiaswhich then becomes the imitin. factor and eads to product variance and because

the sea is hidden inside, can ead to inadvertenty seectin. the wron. seain., hence

sensor%

;etted parts of a pressure sensor with a typica pressure connection


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;etted parts on a pressure sensor with a diaphra.m

Figure 1: Typical wetted Parts of Pressure sensors- anything that comes in contact with the

media (light blue)

&f you woud i)e more information about ;&


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urthermore the term wetted parts aso incudes any interna seas, weds or membranes!

diaphra.ms of the pressure sensor that are "at east partiay# in contact with the media

used%

Typicay wetted parts of pressure sensors are from four cate.ories

Ferrous materials (lie car!on steel" stainless steel etc#$ mainy used for main

bodies! housin.s of sensors and threads etc%

The ma6ority of pressure ports and process connections on industria pressure sensors are

nowadays made from stainess stee and thin7m sensors mainy use stee as the base

materia for the sensor body but the term can be miseadin. as it seems to impy universa

corrosion resistance, which is not the case% 8ways chec) for the speci7c .rade of stainess

stee and chec) corrosion resistance and chemica compatibiity carefuy%

Non%ferrous materials (lie Copper" &rass" Gold" 'astello" Elgilo" )itanium etc#$

typicay used as metaic seain.s or in specia desi.ns for sensor bodies, membranes, or on

diaphra.ms as coatin.s%

&n more economica appications, brass is sti a materia common for vaves and 7ttin.s and

therefore is aso used to buid pressure sensors% or specia appications sometimes the use

of titanium or speciaty aoys "i)e .ioy, 9asteoy, or &ncone# is re/uired to provide hi.h

corrosion resistance or superior measurement performance% (ome eements "i)e -od# are

sometimes used to coat membranes and diaphra.ms as a protection a.ainst corrosion and

chemica attac) or to prevent 9ydro.en to pass throu.h% The cost of some of those materias

and! or the di:cut handin. and machinin. can be prohibitive in certain appications%

Elastomers and Plastics (lie PA" *iton" P)FE etc#$ typicay used as .as)ets, seas or

coatin.s for diaphra.ms

+astics and astomers are used mainy for 3rin.s or as .as)ets and seas, (peciaty

pastics i)e +T are sometimes used as a protective coatin. for membranes and

diaphra.ms%

Ceramics (lie A+,-.$ typicay used as a sensor body! diaphra.m for capacitive or

thic)7m resistive pressure sensors

The use of ceramics as a sensor materia promises hi.h chemica compatibiity and

temperature stabiity that is unfortunatey /uite often compromised because ceramics

cannot be hermeticay seaed by wedin. but aways re/uires the use of "soft# seain.

materiaswhich then becomes the imitin. factor and eads to product variance and because

the sea is hidden inside, can ead to inadvertenty seectin. the wron. seain., hence

sensor%


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;etted parts of a pressure sensor with a typica pressure connection

;etted parts on a pressure sensor with a diaphra.m

Figure 1: Typical wetted Parts of Pressure sensors- anything that comes in contact with the

media (light blue)

&f you woud i)e more information about ;&

wetted parts of pressure sensors

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