316 Stainless Hlau Sheath Phab Ntsa Thickness Ua Li Cas cuam tshuam rau cov hluav taws xob hluav taws xob tam sim no thiab rwb thaiv tsev tiv thaiv kev puas tsuaj nyob rau hauv siab -Vumidity Ib puag ncig?

Cov kws tshuaj xyuas kev nyab xeeb hluav taws xob thiab cov kws tshaj lij kev ruaj ntseg ua haujlwm nrog cov hluav taws xob tso cua sov hauv cov ntawv thov sab nraum zoov, kev ua zaub mov thiab kev tsim tshuaj ib txwm muaj kev txhawj xeeb txog kev tiv thaiv kev puas tsuaj hauv cov av noo siab. Magnesium oxide rwb thaiv tsev nyob ib ncig ntawm cov hlau tsis muaj zog yog hygroscopic, txhais tau tias nws yuav siv cov dej noo los ntawm huab cua thaum lub tshuab cua sov tsis muaj zog yog tias lub plhaub tsis kaw tag nrho. Absorbed noo noo txo ​​cov insulating kuj. Qhov no ua rau cov dej ntws ntws tawm uas yuav ua rau muaj kev tiv thaiv hauv av thiab, thaum muaj xwm txheej, ua rau muaj hluav taws xob poob siab. Cov phab ntsa thickness ntawm cov ntaub ntawv sheath ntawm 316 stainless hlau cuam tshuam rau ob qho tib si noo noo intrusion tus nqi thiab cov hluav taws xob channel ntev rau cov xau tam sim no. Cov kab lus no ntsuas cov phab ntsa thickness, ya raws diffusion thiab rwb thaiv tsev tiv thaiv degradation kev sib raug zoo thiab muab cov lus qhia xaiv rau cov av noo siab.

Moisture Diffusion Los ntawm 316SS Sheaths Thiab End Seals
Dej vapor tuaj yeem cuam tshuam los ntawm phab ntsa sheath ntawm 316 stainless hlau los yog los ntawm qhov kawg cov ntsaws ruaj ruaj qhov twg cov hlau tsis kam tawm ntawm lub sheath, yog li permeating MgO rwb thaiv tsev. Lub permeability ntawm 316 stainless hlau rau dej vapor yog tsawg heev, tab sis tsis xoom. Qhov ruaj khov dej vapor nkag mus txog 1.0 hli tuab 316 ntawm 40℃thiab 100% cov av noo nyob ib puag ncig 0.001 g / m2 / hnub. Qhov no yuav tsawg dua 0.4 grams dej diffused ib square meter ntawm sheath nto nyob rau hauv ib lub xyoo, uas yog negligible rau ib txwm cua sov qhov ntau thiab tsawg. Lub ntsiab infiltration mechanism rau ya raws yog los ntawm microscopic pores nyob rau hauv lub kawg seals, tshwj xeeb tshaj yog nyob rau hauv kev sib cuag ntawm lub sheath, lub MgO, thiab cov ceramic terminal hlaws dai. Rau nyias phab ntsa sheaths hauv qab no 1.0 hli cov neeg kho tshuab ua raws li sheath tso cai rau cov me deformation thaum lub sij hawm thermal cycling uas qhib thiab kaw qhov khoob ntawm qhov kawg seals nqus cua noo rau hauv MgO. Txawm li cas los xij, lawv qhov nruj dua txwv tsis pub siv cov twj tso kua mis no rau tuab- phab ntsa sheaths saum toj 1.8 hli, txo cov dej noo nkag los ntawm qhov zoo ntawm 5 mus rau 10. Yog li cov phab ntsa thickness ntawm cov dej noo ingress yog indirect, tab sis qhov tseem ceeb: cov phab ntsa tuab zoo dua khaws cov kev ncaj ncees ntawm qhov kawg foob nyob rau hauv thermal cycling.

Sheath Phab Ntsa Thickness thiab Path Length ntawm Leakage Tam Sim No
Thaum cov dej noo nkag mus rau MgO, qhov kev tiv thaiv kev tiv thaiv txo qis vim tias cov dej molecules tsim cov kab hluav taws xob raws li qhov chaw ntawm MgO nplej. Cov hluav taws xob xaim tam sim no los ntawm cov hlau tsis kam mus rau hauv av 316 sheath tau radially coj los ntawm MgO txheej. Qhov kev tiv thaiv ntawm txoj kev no yog R=rho x ln (r2 / r1) / (2 pi L) qhov twg rho yog qhov resistivity ntawm moist MgO, r2 thiab r1 yog sab nraud thiab sab hauv radii ntawm MgO txheej thiab L yog qhov ntev ntev. Kev ua kom cov phab ntsa phab ntsa thickness ua rau txo qis cov thickness ntawm MgO txheej rau ib tug tej txheej sheath txoj kab uas hla thiab ruaj tsis kam hlau txoj kab uas hla vim lub sheath yuav siv sij hawm ntau ntawm qhov chaw radial. Thicker phab ntsa sib npaug tsawg MgO ntawm cov hlau thiab sheath. Qhov kev ncua deb me me no ua rau muaj kev tiv thaiv qis dua rau cov ntsiab lus noo noo thiab yog li exacerbates cov teeb meem tam sim no. Piv txwv li, xav txog 10 hli txheej txoj kab uas hla sheath nrog 3 hli txoj kab uas hla tsis kam hlau. Lub thickness ntawm MgO txheej yog 10 - 2 × 1.0 - 3=5 hli, thaum phab ntsa thickness yog 1.0 hli. Nrog rau phab ntsa thickness ntawm 2.0 hli, MgO txheej thickness yog 10 - 4 - 3=3 hli. Lub thinner MgO txheej txo cov radial rwb thaiv tsev los ntawm ib ncig ntawm 40% rau tib MgO resistivity. Yog li ntawd, tuab-walled sheaths yog qhov yooj yim dua rau cov rwb thaiv tsev tsis zoo nyob rau hauv cov ntaub ntawv ntawm noo noo infiltration vim tias muaj tsawg MgO los cuam tshuam cov xau tam sim no.

Critical Phab Ntsa Thickness rau Xaus Foob Kev Ncaj Ncees
Cov lus hauv qab no muab cov lus qhia 316 sheath phab ntsa thicknesses rau hluav taws xob immersion heaters rau high humidity nyob ntawm qhov xav tau ntawm thermal voj voog zaus thiab xav tau rwb thaiv tsev tiv thaiv tom qab txuas ntxiv cia lossis lub sijhawm tsis ua haujlwm. Qhov tseem ceeb xav tias qhov kawg foob kev tsim kho nrog cov hlaws dai thiab epoxy lossis silicone seals.

Cov av noo ib puag ncig xav tau tus naj npawb ntawm Thermal Cycles Ib Xyoo Pom Zoo Yam tsawg kawg 316 Phab Ntsa Thickness Pom Zoo Siab Tshaj 316 Phab Ntsa Thickness Xav Tau Kev Ruaj Ntseg Ua Haujlwm Tom Qab Ib xyoos hauv High HumidityMoisture Penetration 2. Dominant Mechanisms
Qee zaus cov av noo siab (tsawg dua 50% ntawm lub sijhawm) Hauv qab 100 0.8 hli 1.6 hli Tshaj 100 megohms Xaus foob diffusion
Cov av tsis tu ncua (80-100% RH) Tsawg dua 100 1.0 mm 2.0 mm 50 - 200 megohms Diffusion End foob
Tsis tu ncua cov av noo nrog thermal cycling txhua hnub 200 - 500 1.4 hli 2.5 hli 10 - 100 megohms Thermal twj tso kua mis ntawm cov ntsaws ruaj ruaj
Condensing humidity (nquag ntxuav los yog dew) 100 - 300 1.6 hli 2.5 mm 5 - 50 megohms Thermal pumping thiab ncaj qha nkag
Humidity Compression Pressure WashingAny 2.0 mm 2.5 mm 1 – 20 megohms Hermetic seal yuav tsum tau, dej nkag ncaj qha
Any humidity Heater always on Any 0.8 mm 2.5 mm >1,000 megohms Thaum tshav kub kub tshem tawm cov dej noo; tsis muaj deterioration
Txawm li cas los xij, 316 sheath ntawm 1.6 hli los yog tuab yog qhia rau cov ntawv thov nrog cov av noo tas mus li thiab nquag kub caij tsheb kauj vab, txawm tias MgO txheej thickness yuav qis dua. Qhov kom zoo dua ntawm qhov kawg foob kev ncaj ncees overcomes qhov tsis zoo ntawm qhov txo qis txoj kev ntev. Nyob rau hauv cov chaw zoo li no cov engineers yuav tsum tau qhia kom meej cov dej noo tiv thaiv qhov kawg foob tsim, xws li lub iav hermetic - rau - hlau foob los yog ob chav epoxy barrier nrog lub tshuab ziab khaub ncaws nruab nrab.

Tsim Kev Hloov Kho Kev Txhim Kho ntawm Nyias -Walled Sheaths Insulation Resistance
Hauv siab -cov av noo qhov twg nyias -walled 316 sheath<1.2 mm is generally employed for thermal response reasons, three design adjustments exist for maintaining insulation resistance. The first is to apply a moisture barrier coating over the whole sheath and end seal assembly. A conformal coating of parylene or silicone, 50 to 100 microns thick, reduces moisture intrusion by a factor of 10 to 50. The second change is the fitting of a low wattage stand-by heater circuit to maintain the sheath temperature at 50-60 deg C when idling. This keeps the MgO heated enough to avoid condensation of moisture and chases off any water that has been absorbed. Normally the power required is 5-10% of the full heater rating. The third change is the addition of a desiccant filled breather vent to the terminal housing. The desiccant takes moisture before it can get to the end seals. A color-indicating desiccant will change colour when saturated, so that it may be seen inspected and replaced in a timely manner. For essential applications where insulation resistance below 1 megohm can pose a safety threat, engineers should design a heater-service-rated ground fault circuit interrupter. If the MgO insulation has decayed, this provides some protection if there is a leakage over 5-30 mA the GFCI trips. When ordering heaters for high humidity locations, always obtain the insulation resistance test results after 48 hours exposure to 95% relative humidity at 40°C. Most industrial uses call for a heater that will hold 10 megohms or higher under these conditions. If the heater is below 1 megohm it may need more sealing or a different wall thickness.