Nangonaiivalvu zeplastikingamanye amaxesha zithathwa njengemveliso ekhethekileyo-ukhetho lokuqala kubantu abenza okanye abayila iimveliso zeplastiki zemibhobho yeenkqubo zoshishino okanye ekufuneka babe nezixhobo ezicocekileyo kakhulu-ngamafutshane xa sicinga ukuba ezi valve azinazo iindlela ezininzi zokusebenzisa-umbono. Enyanisweni, iivalvu zeplastiki zanamhlanje zinoluhlu olubanzi lokusetyenziswa, kuba iintlobo zezinto ziyaqhubeka nokwanda, kwaye abayili abalungileyo abazifunayo ezi zinto kuthetha ukuba kukho iindlela ezininzi zokusebenzisa ezi zixhobo zininzi.

IIPROPATI ZEPLASTIKI

Iingenelo zeevalvu ze-thermoplastic zibanzi—ukugqwala, ukumelana neekhemikhali kunye nokukrala; iindonga zangaphakathi ezithambileyo; ubunzima obulula; ukulula kokufakelwa; ixesha elide lokuphila; kunye neendleko eziphantsi zomjikelo wobomi. Ezi ngenelo zikhokelele ekwamkelweni ngokubanzi kweevalvu zeplastiki kwizicelo zorhwebo nezoshishino ezifana nokusasazwa kwamanzi, unyango lwamanzi amdaka, ukucutshungulwa kwesinyithi kunye neekhemikhali, ukutya kunye namayeza, izityalo zamandla, iindawo zokucoca ioyile kunye neevalvu zeplastiki ze-mo zinokwenziwa ngezinto ezahlukeneyo ezisetyenziswa kwiindawo ezahlukeneyo. Iivalvu ze-thermoplastic eziqhelekileyo zenziwe nge-polyvinyl chloride (PVC), i-chlorinated polyvinyl chloride (CPVC), i-polypropylene (PP), kunye ne-polyvinylidene fluoride (PVDF). Iivalvu ze-PVC kunye ne-CPVC zihlala zidityaniswe neenkqubo zemibhobho ngeziphelo zesokhethi ze-solvent cementing, okanye iziphelo ezinemisonto kunye ne-flanged; ngelixa, i-PP kunye ne-PVDF zifuna ukuhlanganiswa kwezinto zenkqubo yemibhobho, nokuba ziiteknoloji zobushushu, i-butt- okanye i-electro-fusion.

Iivalvu ze-thermoplastic zibalaseleyo kwiindawo ezirhabaxa, kodwa ziluncedo ngokufanayo kwinkonzo yamanzi ngokubanzi kuba azinalo ilothe1, azinawo umhlwa kwaye azinawo umhlwa. Iinkqubo zemibhobho ze-PVC kunye neevalvu kufuneka zivavanywe kwaye ziqinisekiswe yi-NSF [National Sanitation Foundation] standard 61 ukuze zifumane iziphumo zempilo, kubandakanya imfuneko yelothe ephantsi kwi-Annex G. Ukukhetha izinto ezifanelekileyo zolwelo olurhabaxa kunokuphathwa ngokujonga isikhokelo somenzi sokumelana neekhemikhali kunye nokuqonda isiphumo sobushushu esiya kuba naso kumandla ezinto zeplastiki.

Nangona i-polypropylene inamandla angaphantsi kwesiqingatha se-PVC kunye ne-CPVC, inokumelana neekhemikhali okuguquguqukayo kuba akukho zinyibilikisi zaziwayo. I-PP isebenza kakuhle kwi-acetic acids kunye ne-hydroxides ezixineneyo, kwaye ikwafanelekile kwizisombululo ezithambileyo ze-asidi ezininzi, ii-alkalis, iityuwa kunye neekhemikhali ezininzi ze-organic.

I-PP iyafumaneka njengezinto ezinombala okanye ezingenambala (zendalo). I-PP yendalo yonakaliswa kakhulu yimitha ye-ultraviolet (UV), kodwa iikhompawundi eziqulethe umbala omnyama wekhabhoni ongaphezulu kwe-2.5% zizinzile ngokwaneleyo kwi-UV.

Iinkqubo zemibhobho zePVDF zisetyenziswa kwiindlela ezahlukeneyo zokusebenza kwezoshishino ukusuka kumayeza ukuya kwimigodi ngenxa yamandla ePVDF, ubushushu bokusebenza kunye nokumelana neekhemikhali kwiityuwa, ii-asidi ezinamandla, iziseko ezinyibilikisiweyo kunye nezinye izinyibilikisi ezininzi zendalo. Ngokungafaniyo nePP, iPVDF ayonakaliswa kukukhanya kwelanga; nangona kunjalo, iplastiki ibonakala ngokucacileyo elangeni kwaye inokuveza ulwelo kwimitha ye-UV. Nangona ukwakheka kwendalo, okungenambala wePVDF kulunge kakhulu ekusetyenzisweni ngaphakathi, ukongeza umbala ofana nobomvu wodidi lokutya kuya kuvumela ukuvezwa elangeni ngaphandle kwempembelelo embi kwi-fluid medium.

Iinkqubo zeplastiki zinemingeni yoyilo, efana nokuthambekela kubushushu kunye nokwanda kunye nokuncitshiswa kobushushu, kodwa iinjineli zinokuyila kwaye ziye zayila iinkqubo zemibhobho ezihlala ixesha elide nezingabizi kakhulu kwiindawo eziqhelekileyo nezingcolisayo. Eyona nto iphambili kuyilo kukuba i-coefficient yokwandiswa kobushushu kwiiplastiki inkulu kunesinyithi—i-thermoplastic iphindwe kahlanu ukuya kathandathu kunentsimbi, umzekelo.

Xa kuqulunqwa iinkqubo zombhobho kwaye kuqwalaselwa impembelelo ekubekweni kweevalvu kunye neenkxaso zevalvu, into ebalulekileyo ekuqwalaselweni kwi-thermoplastics kukwandiswa kobushushu. Uxinzelelo kunye namandla abangelwa kukwanda kunye nokucutheka kobushushu anokuncitshiswa okanye apheliswe ngokubonelela ngokuguquguquka kwiinkqubo zombhobho ngokutshintsha rhoqo kwicala okanye ukungeniswa kweeluphu zokwandisa. Ngokubonelela ngolu kuguquguquka kwinkqubo yombhobho, ivalvu yeplastiki ayizukufuneka ukuba ifunxe uxinzelelo oluninzi (Umfanekiso 1).

Ngenxa yokuba ii-thermoplastics zinobuthathaka kubushushu, umlinganiselo woxinzelelo lwevalvu uyancipha njengoko ubushushu bunyuka. Izinto ezahlukeneyo zeplastiki zine-deration ehambelana nobushushu obunyukileyo. Ubushushu bolwelo busenokungabi lolona kuphela umthombo wobushushu onokuchaphazela umlinganiselo woxinzelelo lweevalvu zeplastiki—ubushushu bangaphandle obuphezulu kufuneka bube yinxalenye yokuqwalaselwa koyilo. Kwezinye iimeko, ukungayili ubushushu bangaphandle bepayipi kunokubangela ukuwohloka okugqithisileyo ngenxa yokungabikho kwenkxaso yeepayipi. I-PVC inobushushu obuphezulu benkonzo obuyi-140°F; i-CPVC inobuninzi obuyi-220°F; i-PP inobuninzi obuyi-180°F; kwaye iivalvu ze-PVDF zinokugcina uxinzelelo olufikelela kwi-280°F (Umfanekiso 2).

Kwelinye icala lesikali sobushushu, uninzi lweenkqubo zeplastiki zokufaka imibhobho zisebenza kakuhle kumaqondo obushushu angaphantsi kweqhwa. Enyanisweni, amandla okuxinana ayanda kwimibhobho ye-thermoplastic njengoko ubushushu buncipha. Nangona kunjalo, ukumelana nempembelelo kwenkoliso yeeplastiki kuncipha njengoko ubushushu busehla, kwaye ukuqhekeka kubonakala kwizinto ezichaphazelekileyo zokufaka imibhobho. Ukuba nje iivalvu kunye nenkqubo yokufaka imibhobho ekufutshane aziphazanyiswa, zingachaphazeleki kukubetheka okanye ukungqubana kwezinto, kwaye imibhobho ayiwi ngexesha lokuphathwa, iziphumo ezibi kwimibhobho yeplastiki ziyancitshiswa.

IINTLOBO ZEVALVE ZE-THERMOPLASTIC

Iivalvu zebhola,iivalvu zokujonga,iivalvu zebhabhathanekwaye iivalvu zediaphragm ziyafumaneka kwizixhobo ezahlukeneyo zethermoplastic kwiinkqubo zemibhobho yoxinzelelo lweshedyuli yama-80 ezikwanazo neendlela ezininzi zokulungisa kunye nezixhobo. Ivalvu yebhola eqhelekileyo ifunyanwa kakhulu njengoyilo lomanyano lokwenyani ukwenza kube lula ukususwa komzimba wevalvu ukuze kugcinwe ngaphandle kokuphazamiseka kwemibhobho edibanisayo. Iivalvu zokujonga iThermoplastic ziyafumaneka njengokujonga ibhola, ukujonga iswing, ukujonga i-y kunye nokujonga ikhowuni. Iivalvu zeButterfly zidibana ngokulula neeflange zesinyithi kuba zihambelana nemingxunya yebolthi, izangqa zebolthi kunye nobukhulu obupheleleyo be-ANSI Class 150. Ububanzi obuthambileyo ngaphakathi beendawo zethermoplastic bongeza kuphela kulawulo oluchanekileyo lweevalvu zediaphragm.

Iivalvu zebhola kwiPVC kunye neCPVC zenziwe ziinkampani ezininzi zase-US nezangaphandle ngobukhulu obuyi-1/2 intshi ukuya kwi-6 intshi ezinee-socket, threaded okanye flanged connections. Uyilo lokwenyani lweevalvu zebhola zanamhlanje luquka iinuts ezimbini ezigoqekayo emzimbeni, zicinezela izitywina ze-elastomeric phakathi komzimba kunye nezixhumi zokugqibela. Abanye abavelisi baye bagcina ubude obufanayo bevalvu yebhola kunye neentambo zenuts kangangeminyaka emininzi ukuvumela ukutshintshwa kweevalvu ezindala ngokulula ngaphandle kokutshintshwa kwipayipi ekufutshane.

Iivalvu zebhola ezinee-ethylene propylene diene monomer (EPDM) elastomeric seals kufuneka ziqinisekiswe yi-NSF-61G ukuze zisetyenziswe emanzini okusela. Ii-Fluorocarbon (FKM) elastomeric seals zingasetyenziswa njengendlela eyahlukileyo kwiinkqubo apho ukuhambelana kweekhemikhali kuyingxaki. I-FKM ingasetyenziswa nakwiinkqubo ezininzi ezibandakanya ii-mineral acids, ngaphandle kwe-hydrogen chloride, izisombululo zetyuwa, ii-chlorinated hydrocarbons kunye neeoyile zepetroleum.

Umfanekiso 3. Ivalvu yebhola ejijekileyo eqhotyoshelwe kwitanki Umfanekiso 4. Ivalvu yokujonga ibhola efakwe ngokuthe nkqo Iivalvu zebhola zePVC kunye neCPVC, ezisuka kwi-1/2-intshi ukuya kwi-2 intshi, ziyindlela efanelekileyo yokusetyenziswa kwamanzi ashushu nabandayo apho inkonzo ephezulu yamanzi angengomtshiso inokuba yi-250 psi kwi-73°F. Iivalvu zebhola ezinkulu, ezisuka kwi-2-1/2 intshi ukuya kwi-6 intshi, ziya kuba nomlinganiselo woxinzelelo ophantsi we-150 psi kwi-73°F. Ezisetyenziswa rhoqo ekuhanjisweni kweekhemikhali, iivalvu zebhola zePP kunye nePVDF (Imifanekiso 3 kunye no-4), ezifumaneka ngobukhulu obuphakathi kwe-1/2-intshi ukuya kwi-4 intshi kunye neesokhethi, imisonto okanye uqhagamshelo olune-flanged zihlala zilinganiswa kwinkonzo ephezulu yamanzi angengomtshiso ye-150 psi kubushushu obuphakathi.

Iivalvu zokujonga ibhola ze-thermoplastic zixhomekeke kwibhola enobunzima obuthile obungaphantsi kobo bamanzi, ukuze ukuba uxinzelelo lulahlekile kwicala elingaphezulu, ibhola liza kutshona libuyele kumphezulu wokuvala. Ezi valve zingasetyenziswa kwinkonzo efanayo neevalvu zebhola zeplastiki ezifanayo kuba azingenisi izinto ezintsha kwinkqubo. Ezinye iintlobo zeevalvu zokujonga zinokubandakanya izipringi zesinyithi ezisenokungahlali kwindawo ezirhabaxa.

Umfanekiso 5. Ivalvu yebhabhathane ene-elastomeric liner. Ivalvu yebhabhathane yeplastiki ngobukhulu obuphakathi kwe-intshi ezi-2 ukuya kwi-intshi ezingama-24 idumile kwiinkqubo zemibhobho emikhulu. Abavelisi beevalvu zebhabhathane zeplastiki bathatha iindlela ezahlukeneyo zokwakha kunye nokutywina umphezulu. Abanye basebenzisa i-elastomeric liner (Umfanekiso 5) okanye i-O-ring, ngelixa abanye basebenzisa idiski ene-elastomeric-coated disc. Abanye benza umzimba ngento enye, kodwa izinto zangaphakathi, ezimanzi zisebenza njengezixhobo zenkqubo, oko kuthetha ukuba umzimba wevalvu yebhabhathane ye-polypropylene unokuba ne-EPDM liner kunye ne-PVC disc okanye ezinye izinto ezininzi ezine-thermoplastics kunye ne-elastomeric seals eziqhelekileyo.

Ukufakwa kwevalvu yebhabhathane yeplastiki kulula kuba ezi valve zenziwe ngohlobo lwe-wafer ene-elastomeric seals ezenzelwe umzimba. Azidingi kongezwa kwe-gasket. Zibekwe phakathi kwee-flanges ezimbini zokudibana, ukuxhonywa kwevalvu yebhabhathane yeplastiki kufuneka kuphathwe ngononophelo ngokunyuka ukuya kwi-torque yebholthi ecetyiswayo ngamanqanaba amathathu. Oku kwenziwa ukuqinisekisa ukuba itywina lilingana kumphezulu kwaye akukho xinzelelo loomatshini olungalinganiyo olufakwa kwivalvu.

Umfanekiso 6. Ivalvu yediaphragmIingcali zeevalvu zesinyithi ziya kufumana imisebenzi ephezulu yeevalvu zediaphragm zeplastiki ezineesalathisi zevili kunye nendawo eziqhelekile (Umfanekiso 6); nangona kunjalo, ivalvu yediaphragm yeplastiki ingabandakanya ezinye iingenelo ezahlukeneyo kubandakanya iindonga ezigudileyo zangaphakathi zomzimba we-thermoplastic. Njengevalvu yebhola yeplastiki, abasebenzisi bezi valve banokukhetha ukufaka uyilo lokwenyani lomanyano, olunokuba luncedo ngakumbi kumsebenzi wokulungisa kwivalvu. Okanye, umsebenzisi angakhetha uqhagamshelo oludibeneyo. Ngenxa yazo zonke iindlela zomzimba kunye nezixhobo zediaphragm, le valve ingasetyenziswa kwiindlela ezahlukeneyo zokusetyenziswa kweekhemikhali.

Njengakweyiphi na ivalvu, isitshixo sokuqalisa iivalvu zeplastiki kukumisela iimfuno zokusebenza ezifana namandla omoya ngokuchasene nombane kunye namandla e-DC ngokuchasene ne-AC. Kodwa ngeplastiki, umyili kunye nomsebenzisi kufuneka baqonde ukuba loluphi uhlobo lwendawo oluya kujikeleza i-actuator. Njengoko bekutshiwo ngaphambili, iivalvu zeplastiki ziyindlela entle kwiimeko zokubola, ezibandakanya iindawo zokubola ngaphandle. Ngenxa yoku, izinto zokuhlala zee-actuators zeevalvu zeplastiki zibalulekile. Abavelisi beevalvu zeplastiki baneendlela zokuhlangabezana neemfuno zezi ndawo zokubola ngendlela yee-actuators ezigqunywe ngeplastiki okanye ii-metal cases ezigqunywe yi-epoxy.

Njengoko eli nqaku libonisa, iivalvu zeplastiki namhlanje zibonelela ngeendlela ezahlukeneyo zokusetyenziswa kunye neemeko ezintsha.