Nangonaiivalvu zeplastikimaxa wambi zithathwa njengemveliso ekhethekileyo-ukhetho lokuqala kubantu abenza okanye abayila iimveliso zemibhobho yeplastiki kwiinkqubo zamashishini okanye ekufuneka babenezixhobo ezicoceke kakhulu-kuyinto emfutshane kucingelwa ukuba ezi zivalo azinakusetyenziswa ngokubanzi-umbono. Enyanisweni, iivalve zeplastiki zanamhlanje zineendlela ezininzi zokusetyenziswa, kuba iintlobo zezixhobo ziyaqhubeka zanda, kwaye abaqulunqi abalungileyo abafuna ezi zinto zithetha ukuba kukho iindlela ezininzi zokusebenzisa ezi zixhobo ezininzi.

IIPROPATI ZEPLASTIKI

Iingenelo zee-valve ze-thermoplastic zibanzi-i-corrosion, i-chemical and abrasion resistance; iindonga ezigudileyo zangaphakathi; ubunzima obulula; lula ukufakela; ixesha elide lokuphila; kunye neendleko eziphantsi zomjikelo wobomi. Ezi nzuzo zikhokelele ekwamkelweni okubanzi kweevalvu zeplastiki kwizicelo zorhwebo nakwimizi-mveliso ezifana nokuhanjiswa kwamanzi, ukucocwa kwamanzi amdaka, ukusetyenzwa kwesinyithi kunye neekhemikhali, ukutya kunye namayeza, izityalo zamandla, iindawo zokucokisa ioyile kunye neevalvu ze-moPlastic zinokuveliswa kwinani lezinto ezahlukeneyo ezisetyenzisiweyo. kwinani loqwalaselo. Iivalve ze-thermoplastic eziqhelekileyo zenziwe nge-polyvinyl chloride (PVC), i-polyvinyl chloride eyi-chlorinated (CPVC), i-polypropylene (PP), kunye ne-polyvinylidene fluoride (PVDF). Iivalvu ze-PVC kunye ne-CPVC zidla ngokudityaniswa kwiinkqubo zokubhobhoza ngokudibanisa iziphelo zesamente ye-solvent, okanye iziphelo ezinemisonto kunye ne-flanged; kanti, iPP kunye nePVDF zifuna ukudibanisa amacandelo enkqubo yemibhobho, mhlawumbi ngobushushu, impundu- okanye iteknoloji ye-electro-fusion.

Iivalvu ze-Thermoplastic zigqwesa kwindawo enomhlwa, kodwa ziluncedo ngokufanayo kwinkonzo yamanzi ngokubanzi kuba azina lead1, ziyakwazi ukumelana ne-dezincification kwaye aziyi kurusi. Iinkqubo zemibhobho ye-PVC kunye ne-CPVC kunye neevalvu kufuneka zivavanywe kwaye zingqinwe kwi-NSF [National Sanitation Foundation] umgangatho we-61 weziphumo zempilo, kubandakanywa nemfuno ephantsi ehamba phambili yeSihlomelo G. Ukukhetha imathiriyeli efanelekileyo yolwelo oluhlwayo lunokuphathwa ngokubonisana nokumelana nemichiza yomenzi. isikhokelo kunye nokuqonda ifuthe lobushushu eliya kuba nalo kumandla ezinto zeplastiki.

Nangona i-polypropylene inesiqingatha samandla e-PVC kunye ne-CPVC, ineyona nto ixhaphakileyo yokuxhathisa imichiza ngenxa yokuba akukho zinyibilikisi ezaziwayo. I-PP iqhuba kakuhle kwi-acetic acid kunye ne-hydroxides egxininisiweyo, kwaye ifanelekile kwizisombululo ezithambileyo ze-acids ezininzi, i-alkalis, iityuwa kunye neekhemikhali ezininzi eziphilayo.

I-PP ifumaneka njenge-pigmented or unpigmented (yendalo). I-PP yendalo yonakaliswa kakhulu yimitha ye-ultraviolet (UV), kodwa iikhompawundi eziqulethe ngaphezu kwe-2.5% ye-carbon black pigmentation i-UV izinzileyo ngokwaneleyo.

Iinkqubo zemibhobho ye-PVDF zisetyenziswa kwiintlobo ngeentlobo zezicelo zemizi-mveliso ukusuka kumayeza ukuya emigodini ngenxa yamandla e-PVDF, ubushushu obusebenzayo kunye nokumelana neekhemikhali kwiityuwa, ii-asidi ezinamandla, iziseko ezidityanisiweyo kunye nezinyibilikisi ezininzi zezinto eziphilayo. Ngokungafaniyo nePP, iPVDF ayithotywanga kukukhanya kwelanga; nangona kunjalo, iplastiki iyabonakala ekukhanyeni kwelanga kwaye inokuveza ulwelo kwimitha ye-UV. Ngelixa i-PVDF yendalo, i-unpigmented formulation igqwesile kucoceko oluphezulu, izicelo zangaphakathi, ukongeza ibala elibomvu elifana nokutya okubomvu kuya kuvumela ukuchanabeka elangeni ngaphandle kwesiphumo esibi kwindlela yolwelo.

Iinkqubo zePlastiki zinemingeni yoyilo, efana nobuntununtunu kwiqondo lobushushu kunye nokwandiswa kobushushu kunye nokucutheka, kodwa iinjineli zinako kwaye zenze iinkqubo zemibhobho ehlala ixesha elide, enexabiso eliphantsi lemibhobho jikelele kunye neyonakalisayo. Ingqwalasela enkulu yoyilo kukuba i-coefficient yokwandiswa kwe-thermal yeeplastiki inkulu kunesinyithi-i-thermoplastic iphindwe kahlanu ukuya kwesithandathu, ngokomzekelo.

Xa uyila iinkqubo zemibhobho kwaye uqwalasela impembelelo ekubekweni kwevalve kunye neenkxaso zevalve, ukuqwalaselwa okubalulekileyo kwi-thermoplastics kubude be-thermal. Uxinzelelo kunye nemikhosi ebangelwa ukwanda kwe-thermal kunye nokunciphisa kungancitshiswa okanye kupheliswe ngokubonelela ukuguquguquka kwiinkqubo zemibhobho ngokutshintsha rhoqo kwindlela okanye ukuqaliswa kwe-loops yokwandisa. Ngokubonelela ngolu hlobo oluguquguqukayo kunye nenkqubo yokubhobhoza, i-valve yeplastiki ayiyi kufunwa ukuba ithathe ubuninzi boxinzelelo (Umfanekiso 1).

Ngenxa yokuba i-thermoplastics ivakalelwa kwiqondo lokushisa, izinga loxinzelelo lwevalve liyehla njengoko ubushushu buphakama. Izinto ezahlukeneyo zeplastiki zineempawu ezihambelanayo kunye nokunyuka kobushushu. Iqondo lobushushu lolwelo lisenokungabi ngowona mthombo wobushushu kuphela onokuchaphazela umlinganiselo woxinzelelo lweevalvu zeplastiki—ubushushu obona buninzi bangaphandle bufuna ukuba yinxalenye yoqwalaselo loyilo. Kwezinye iimeko, ukungacwangciswa kobushushu bangaphandle bombhobho kunokubangela ukudodobala okugqithisileyo ngenxa yokungabikho kwezixhasi zemibhobho. I-PVC inobushushu benkonzo obuphezulu be-140 ° F; I-CPVC inobuninzi be-220 ° F; I-PP inobuninzi be-180 ° F; kunye neevalve ze-PVDF zinokugcina uxinzelelo ukuya kwi-280 ° F (Umfanekiso 2).

Kwelinye icala lesikali sobushushu, uninzi lweenkqubo zemibhobho yeplastiki zisebenza kakuhle kumaqondo obushushu angaphantsi kweqondo lomkhenkce. Ngapha koko, amandla okuqina ayanda kwimibhobho ye-thermoplastic njengoko ubushushu buyancipha. Nangona kunjalo, ukuchasana kwempembelelo yeeplastiki ezininzi kuncipha njengoko ubushushu buhla, kwaye ukonakala kubonakala kwizinto ezichaphazelekayo zokubhobhoza. Logama nje iivalve kunye nenkqubo yombhobho edityanisiweyo ingaphazamiseki, ayingonakaliswa kukuvuthela okanye ukungqubana kwezinto, kwaye umbhobho awuwiswanga ngexesha lokuphatha, iziphumo ezibi kumbhobho weplastiki ziyancitshiswa.

IINTLOBO ZEVAVAVA ZE-THERMOPLASTIC

Iivalve zebhola,khangela iivalve,iivalve butterflykunye neevalvu ze-diaphragm ziyafumaneka kwisixhobo ngasinye se-thermoplastic eyahlukeneyo kwishedyuli ye-80 yeenkqubo zoxinzelelo lwemibhobho ekwanayo inkitha yokukhetha kunye nezixhobo. Ivalve yebhola esemgangathweni idla ngokufunyaniswa iluyilo lomanyano lokwenyani ukuququzelela ukususwa komzimba wevalve ukulungiselela ulondolozo ngaphandle kokuphazamiseka kwemibhobho yokudibanisa. Iivalvu zokujonga i-Thermoplastic ziyafumaneka njengeetshekhi zebhola, iitshekhi zokujingi, iitshekhi kunye neetshekhi zekhowuni. Iivalve zebhabhathane zidibana ngokulula neeflange zentsimbi kuba zihambelana nemingxunya yebholiti, izangqa zebholiti kunye nemilinganiselo epheleleyo ye-ANSI yoKlasi 150. Idayamitha egudileyo yangaphakathi yamalungu e-thermoplastic yongeza kuphela kulawulo oluchanekileyo lweevalvu ze-diaphragm.

Iivalvu zebhola kwi-PVC kunye ne-CPVC zenziwe ngamaqela amaninzi ase-US kunye neenkampani zangaphandle ngobukhulu be-1/2 intshi nge-intshi ezi-6 ezinesokethi, intambo okanye i-flanged. Uyilo oluyinyani lomanyano lweevalvu zebhola zangoku lubandakanya amandongomane amabini ajija umzimba, ukucinezela izitywina ze-elastomeric phakathi komzimba kunye nezihlanganisi eziphela. Abanye abavelisi bagcine ivalve yebhola efanayo yokubeka ubude kunye nemisonto yenut kangangamashumi eminyaka ukuvumela ukutshintshwa lula kweevalvu ezindala ngaphandle kokuguqulwa kwemibhobho edibanayo.

Iivalvu zebhola ezine-ethylene propylene diene monomer (EPDM) i-elastomeric seals kufuneka ziqinisekiswe kwi-NSF-61G ukuze zisetyenziswe emanzini aselwayo. I-Fluorocarbon (FKM) izitywini ze-elastomeric zingasetyenziswa njengenye indlela kwiinkqubo apho ukuhambelana kweekhemikhali kuyinkxalabo. I-FKM inokusetyenziswa kwizicelo ezininzi ezibandakanya ii-acids zeminerali, ngaphandle kwe-hydrogen chloride, izisombululo zetyuwa, ii-hydrocarbon ezikloriniweyo kunye ne-oyile ye-petroleum.

Umfanekiso 3. Ivalve yebhola eneflanged encanyathiselwe kwitankiUmfanekiso 4. Ivalve yokukhangela ibhola efakwe ngokuthe nkqo iPVC kunye neCPVC iivalve zebhola, 1/2-intshi ukuya kwii-intshi ezi-2, lukhetho olusebenzayo kusetyenziso lwamanzi ashushu nabandayo apho awona manzi aphezulu angawothukiyo. inkonzo inokuba nkulu kangange 250 psi ku 73°F. Iivalve ezinkulu zebhola, i-2-1/2 intshi ukuya kwii-intshi ezi-6, ziya kuba noxinzelelo oluphantsi lwe-150 psi kwi-73 ° F. Ngokuqhelekileyo isetyenziselwa ukuhanjiswa kweekhemikhali, i-PP kunye ne-PVDF iivalvu zebhola (i-Figure 3 kunye ne-4), ekhoyo ngobukhulu be-1/2-intshi ukuya kwi-intshi ezi-4 ezinesokethi, i-threaded okanye i-flanged-end-end-flanged ixhaphake inikwe ubuninzi benkonzo yamanzi engothukiyo. 150 psi kwiqondo lobushushu ambient.

I-Thermoplastic ball check valves ixhomekeke kwibhola enobunzima obuthile obungaphantsi kobo bamanzi, ukuze ukuba uxinzelelo lulahlekile kwicala elingasentla, ibhola iya kuzika ibuyele kumphezulu wokutywina. Ezi zivalo zinokusetyenziswa kwinkonzo efanayo kunye neevalvu zebhola zeplastiki ezifanayo ngenxa yokuba azizisi izinto ezintsha kwinkqubo. Ezinye iintlobo zeevalvu zokutshekisha zingabandakanya imithombo yesinyithi enokuthi ingapheli kwiindawo ezinobungozi.

Umzobo 5. Ivalve yebhabhathane ene-elastomeric linerIvalve yebhabhathane yeplastiki ngokwesayizi ye-intshi ezi-2 ukuya kwi-intshi ezingama-24 ithandwa kakhulu kwiinkqubo ezinkulu zemibhobho edayamitha. Abavelisi beevalvu zebhabhathane zeplastiki bathatha iindlela ezahlukeneyo ekwakhiweni nasekuvaleni umphezulu. Abanye basebenzisa i-elastomeric liner (Umfanekiso 5) okanye i-O-ring, ngelixa abanye basebenzisa i-elastomeric-coated disc. Abanye benza umzimba ngaphandle kwesixhobo esinye, kodwa amacandelo angaphakathi, amanzi asebenza njengezixhobo zenkqubo, oku kuthetha ukuba umzimba wevalve yebhabhathane ye-polypropylene unokuba ne-EPDM liner kunye ne-PVC disc okanye ezinye izilungiso ezine-thermoplastics ezifumaneka ngokuqhelekileyo kunye ne-elastomeric seals.

Ukufakwa kwevalve yebhabhathane yeplastiki kuthe ngqo kuba ezi zivalo zenziwe ukuba zibe sisitayile se-wafer esinezitywina ze-elastomeric eziyilwe emzimbeni. Abafuni ukongezwa kwe-gasket. Ukuseta phakathi kweeflange ezimbini zokukhwelana, ukubolithwa kwevalve yebhabhathane yeplastiki kufuneka kuphathwe ngononophelo ngokunyuka ukuya kwitorque ecetyiswayo ngezigaba ezithathu. Oku kwenzelwa ukuqinisekisa itywina elilinganayo kuwo wonke umphezulu kwaye akukho xinzelelo lomatshini olungalinganiyo lufakwa kwivalvu.

Umzobo 6. Ivalve ye-diaphragm Iingcali zevalvu yesinyithi ziya kufumana imisebenzi ephezulu yeevalvu zeplastiki ezinevili kunye nezalathi zokuma eziqhelekileyo (Umfanekiso 6); nangona kunjalo, ivalve yeplastiki ye-diaphragm inokubandakanya iingenelo ezithile ezahlukileyo kubandakanya iindonga ezigudileyo zangaphakathi zomzimba we-thermoplastic. Ngokufana nevalve yebhola yeplastiki, abasebenzisi bezi zivalo banenketho yokufakela uyilo lomanyano lwenyani, olunokuba luncedo ngakumbi kumsebenzi wokulondoloza kwivalve. Okanye, umsebenzisi unokukhetha imidibaniso ene-flanged. Ngenxa yazo zonke iinketho zomzimba kunye nezixhobo ze-diaphragm, le valve inokusetyenziswa kwiinkqubo ezahlukeneyo zemichiza.

Njengayo nayiphi na ivalve, isitshixo sokuvula iivalvu zeplastiki kukumisela iimfuno zokusebenza ezifana ne-pneumatic versus electric kunye ne-DC ngokuchasene namandla e-AC. Kodwa ngeplastiki, umyili kunye nomsebenzisi kufuneka baqonde ukuba loluphi uhlobo lokusingqongileyo oluya kujikeleza i-actuator. Njengoko kukhankanyiwe ngaphambili, iivalvu zeplastiki lukhetho olukhulu kwiimeko ezinobungozi, ezibandakanya iindawo ezinobungozi zangaphandle. Ngenxa yoko, izinto zezindlu ze-actuator ze-valve zeplastiki zibalulekile ingqalelo. Abavelisi bevalvu yeplastiki banokhetho lokuhlangabezana neemfuno zezi ndawo zidlayo ngokohlobo lwee-actuator ezigqunywe ngeplastiki okanye iimeko zentsimbi ezigqunywe nge-epoxy.

Njengoko eli nqaku libonisa, iivalve zeplastiki namhlanje zinika zonke iintlobo zokhetho kwizicelo ezintsha kunye neemeko.