Ngakhale mavavu apulasitiki nthawi zina amawoneka ngati chinthu chapadera-chisankho chapamwamba cha omwe amapanga kapena kupanga zida zamapaipi apulasitiki pamafakitale kapena omwe ayenera kukhala ndi zida zoyeretsera kwambiri - poganiza kuti ma valvewa alibe ntchito zambiri ndi zazifupi. wowona. Zoona zake, mavavu apulasitiki masiku ano ali ndi ntchito zambiri monga momwe mitundu yowonjezera ya zipangizo ndi okonza abwino omwe amafunikira zipangizozo amatanthauza njira zambiri zogwiritsira ntchito zipangizozi.
ZINTHU ZA PLASTIC
Ubwino wa ma valve a thermoplastic ndi otakata-kudzimbirira, kukana mankhwala ndi abrasion; makoma amkati osalala; kulemera kochepa; mosavuta kukhazikitsa; kuyembekezera moyo wautali; ndi kutsika mtengo kwa moyo. Ubwino umenewu wapangitsa kuti ma valve apulasitiki avomerezedwe m'zinthu zamalonda ndi mafakitale monga kugawa madzi, kuyeretsa madzi otayira, kukonza zitsulo ndi mankhwala, chakudya ndi mankhwala, mafakitale opangira magetsi, mafuta opangira mafuta ndi zina.
Mavavu apulasitiki amatha kupangidwa kuchokera kuzinthu zosiyanasiyana zomwe zimagwiritsidwa ntchito pamasinthidwe angapo. Ma valve odziwika kwambiri a thermoplastic amapangidwa ndi polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC), polypropylene (PP), ndi polyvinylidene fluoride (PVDF). Mavavu a PVC ndi CPVC nthawi zambiri amalumikizana ndi mapaipi pogwiritsa ntchito ma socket socket sockets, kapena ulusi ndi nsonga zopindika; pomwe, PP ndi PVDF zimafuna kulumikizidwa kwa zida zamapaipi, mwina pogwiritsa ntchito matekinoloje a kutentha, matako kapena ma electro-fusion.
Mavavu a thermoplastic amapambana kwambiri m'malo ochita dzimbiri, koma ndi othandizanso pamadzi wamba chifukwa alibe lead1, sachita dzimbiri ndipo sachita dzimbiri. PVC ndi CPVC mapaipi ndi mavavu ayenera kuyesedwa ndi certification ku NSF [National Sanitation Foundation] muyezo 61 zotsatira thanzi, kuphatikizapo otsika kufunikira kwa Annex G. Kusankha zinthu zoyenera za madzi zikuwononga akhoza kugwiridwa mwa kufunsa wopanga mankhwala kukana kuwongolera ndi kumvetsetsa momwe kutentha kudzakhudzira mphamvu ya zida zapulasitiki.
Ngakhale polypropylene ili ndi theka la mphamvu za PVC ndi CPVC, imakhala ndi mphamvu zambiri zotsutsana ndi mankhwala chifukwa palibe zosungunulira zodziwika. PP imagwira ntchito bwino mu ma acetic acid ndi ma hydroxides, komanso ndiyoyeneranso njira zochepetsera ma acid ambiri, ma alkali, mchere ndi mankhwala ambiri achilengedwe.
PP imapezeka ngati zinthu zamtundu kapena zopanda pigmented (zachilengedwe). Natural PP imawonongeka kwambiri ndi cheza cha ultraviolet (UV), koma mankhwala omwe ali ndi 2.5% ya carbon black pigmentation ndi UV yokhazikika mokwanira.
PVDF mapaipi amagwiritsidwa ntchito m'mafakitale osiyanasiyana kuchokera ku mankhwala kupita ku migodi chifukwa cha mphamvu ya PVDF, kutentha kwa ntchito ndi kukana kwa mankhwala amchere, ma asidi amphamvu, zosungunulira ndi zosungunulira zambiri. Mosiyana ndi PP, PVDF sichidetsedwa ndi kuwala kwa dzuwa; komabe, pulasitiki ndi yowonekera ku kuwala kwa dzuwa ndipo imatha kuyika madziwa ku radiation ya UV. Ngakhale mawonekedwe achilengedwe, opanda pigment a PVDF ndi abwino kwambiri pakuyeretsa kwambiri, kugwiritsa ntchito m'nyumba, kuwonjezera pigment ngati chakudya chofiira kumapangitsa kuti pakhale kuwala kwadzuwa popanda vuto lililonse pamadzimadzi.
Makina apulasitiki ali ndi zovuta zamapangidwe, monga kukhudzika kwa kutentha ndi kufutukuka kwa kutentha ndi kutsika, koma mainjiniya amatha kupanga mapaipi okhalitsa, otsika mtengo a malo wamba komanso owononga. Kulingalira kwakukulu kwapangidwe ndikuti coefficient of thermal expansion for plastics ndi yaikulu kuposa zitsulo-thermoplastic ndi kasanu kapena kasanu ndi kachitsulo kachitsulo, mwachitsanzo.
Popanga mapaipi opangira mapaipi ndikuganizira momwe ma valve amayika ndi ma valve, chofunikira kwambiri mu thermoplastics ndi kutalika kwa kutentha. Kupsyinjika ndi mphamvu zomwe zimabwera chifukwa cha kuwonjezereka kwa kutentha ndi kutsika kumatha kuchepetsedwa kapena kuthetsedwa mwa kupereka kusinthasintha kwa machitidwe a mapaipi kupyolera mu kusintha kwafupipafupi kapena kuyambitsa malupu owonjezera. Popereka kusinthasintha kumeneku pamayendedwe a mapaipi, valavu ya pulasitiki sidzafunikanso kuti itenge nkhawa zambiri
Chifukwa thermoplastics imakhudzidwa ndi kutentha, kuthamanga kwa valve kumachepa pamene kutentha kumakwera. Zida zapulasitiki zosiyanasiyana zimakhala ndi deration yofananira ndi kutentha kwakukulu. Kutentha kwamadzi sikuyenera kukhala gwero lotentha lokhalo lomwe lingakhudze kuchuluka kwa mphamvu ya mavavu apulasitiki - kutentha kwakukulu kwakunja kuyenera kukhala gawo loganizira kapangidwe kake. Nthawi zina, kusapanga kwa mipope yakunja kutentha kungayambitse kutsika kwambiri chifukwa chosowa zothandizira chitoliro. PVC ili ndi kutentha kwakukulu kwa utumiki wa 140 ° F; CPVC ili ndi kutentha kwa 220 ° F; PP imakhala ndi kutentha kwa 180 ° F; ndi mavavu a PVDF amatha kukhala ndi mphamvu mpaka 280 ° F
Kumbali ina ya kutentha, makina ambiri opopera mapaipi apulasitiki amagwira ntchito bwino pakutentha kosazizira kwambiri. M'malo mwake, kulimba kwamphamvu kumawonjezeka mu mapaipi a thermoplastic pamene kutentha kumachepa. Komabe, kukana kwamphamvu kwa mapulasitiki ambiri kumachepera pamene kutentha kumatsika, ndipo brittleness imawoneka pazipaipi zomwe zakhudzidwa. Malingana ngati ma valve ndi makina oyandikana nawo amakhala osasokonezeka, osawopsezedwa ndi nkhonya kapena kugunda kwa zinthu, ndipo mapaipiwo sakugwetsedwa panthawi yogwira, zotsatira zovulaza ku mapaipi apulasitiki zimachepetsedwa.
MITUNDU YA MAVAVU A THERMOPLASTIC
Mavavu ampira, ma valavu owunika, ma valve agulugufe ndi ma diaphragm akupezeka muzinthu zosiyanasiyana za thermoplastic za ndandanda 80 yamapaipi amphamvu omwe alinso ndi njira zambiri zochepetsera ndi zowonjezera. Valavu yokhazikika ya mpira nthawi zambiri imapezeka kuti ndiyopanga mgwirizano weniweni kuti ithandizire kuchotsedwa kwa ma valve kuti ikonzedwe popanda kusokoneza mapaipi olumikizira. Ma valve a Thermoplastic cheque amapezeka ngati macheke a mpira, ma cheki opindika, ma y-check ndi ma cone. Mavavu agulugufe amalumikizana mosavuta ndi ma flanges achitsulo chifukwa amagwirizana ndi mabowo a bawuti, mabwalo a bawuti ndi miyeso yonse ya ANSI Class 150. Mkati mwake mkati mwa zigawo za thermoplastic zimangowonjezera kuwongolera bwino kwa ma valve a diaphragm.
Ma valve a mpira mu PVC ndi CPVC amapangidwa ndi makampani angapo aku US ndi akunja kukula kwake 1/2 inchi kudzera mainchesi 6 okhala ndi socket, ulusi kapena flanged. Mapangidwe enieni a mgwirizano wamavavu ampira amakono amaphatikiza mtedza awiri omwe amamangirira pathupi, kukanikiza zisindikizo za elastomeric pakati pa thupi ndi zolumikizira mapeto. Opanga ena akhala ndi valavu yofanana ya mpira ndi ulusi wa mtedza kwa zaka zambiri kuti alole kusintha kosavuta kwa mavavu akale popanda kusinthidwa kwa mapaipi olumikizana.
Mavavu a mpira okhala ndi ethylene propylene diene monomer (EPDM) elastomeric seals ayenera kutsimikiziridwa ku NSF-61G kuti agwiritsidwe ntchito m'madzi amchere. Zisindikizo za Fluorocarbon (FKM) elastomeric zitha kugwiritsidwa ntchito ngati njira ina yamakina omwe ali ndi nkhawa. FKM itha kugwiritsidwanso ntchito pazinthu zambiri zophatikiza ma mineral acids, kupatula ma hydrogen chloride, salt solutions, chlorinated hydrocarbons ndi mafuta a petroleum.
Mavavu a mpira a PVC ndi CPVC, 1/2-inch kupyolera mu 2 mainchesi, ndi njira yabwino yogwiritsira ntchito madzi otentha ndi ozizira kumene madzi osagwedezeka amatha kukhala 250 psi pa 73 ° F. Mavavu akulu akulu, mainchesi 2-1/2 kupyola mainchesi 6, adzakhala ndi mphamvu yotsika ya 150 psi pa 73 ° F. Zomwe zimagwiritsidwa ntchito ponyamula mankhwala, ma valve a PP ndi PVDF (Zithunzi 3 ndi 4), zomwe zimapezeka mu makulidwe 1/2 inchi mpaka mainchesi 4 okhala ndi socket, zolumikizira za ulusi kapena zopindika nthawi zambiri zimavotera madzi osagwedezeka. 150 psi pa kutentha kozungulira.
Ma valve owunika a Thermoplastic amadalira mpira wokhala ndi mphamvu yokoka yocheperako kuposa yamadzi, kotero kuti ngati kuthamanga kutayika kumbali yakumtunda, mpirawo ubwereranso kumtunda wosindikiza. Ma valve awa angagwiritsidwe ntchito muutumiki womwewo monga ma valve a pulasitiki ofanana ndi mpira chifukwa samayambitsa zipangizo zatsopano ku dongosolo. Mitundu ina ya ma check valves ingaphatikizepo akasupe achitsulo omwe sangakhale m'malo owononga.
Vavu yagulugufe ya pulasitiki yokulirapo mainchesi 2 mpaka mainchesi 24 ndiyodziwika pamapaipi akulu akulu akulu. Opanga ma valve agulugufe a pulasitiki amatenga njira zosiyanasiyana pomanga ndi kusindikiza malo. Ena amagwiritsa ntchito chingwe cha elastomeric (Chithunzi 5) kapena O-ring, pamene ena amagwiritsa ntchito disc elastomeric-coated. Zina zimapanga thupi kuchokera ku chinthu chimodzi, koma zamkati, zonyowa zimakhala ngati zipangizo zamakina, kutanthauza kuti polypropylene butterfly valve thupi likhoza kukhala ndi EPDM liner ndi PVC disc kapena masinthidwe ena angapo omwe amapezeka kawirikawiri thermoplastics ndi elastomeric zisindikizo.
Kuyika valavu ya gulugufe wa pulasitiki ndikosavuta chifukwa mavavuwa amapangidwa kuti akhale mawonekedwe opindika okhala ndi zisindikizo za elastomeric zomwe zimapangidwira m'thupi. Iwo safuna Kuwonjezera wa gasket. Pokhala pakati pa nthiti ziwiri zokwerera, kutsekereza kwa vavu ya gulugufe wa pulasitiki kuyenera kusamaliridwa mosamala pokwerera kokeki kovomerezeka m'magawo atatu. Izi zimachitidwa kuti zitsimikizire kuti chisindikizo chofanana pamtunda komanso kuti palibe kupanikizika kwa makina komwe kumagwiritsidwa ntchito pa valve.
Akatswiri azitsulo azitsulo adzapeza ntchito zapamwamba za mavavu apulasitiki a diaphragm okhala ndi gudumu ndi zizindikiro zodziwika bwino (Chithunzi 6); komabe, valavu ya pulasitiki ya diaphragm ikhoza kukhala ndi ubwino wina wosiyana kuphatikizapo makoma osalala a mkati mwa thupi la thermoplastic. Mofanana ndi valavu ya mpira wa pulasitiki, ogwiritsa ntchito ma valvewa ali ndi mwayi wokhazikitsa ndondomeko yeniyeni ya mgwirizano, yomwe ingakhale yothandiza kwambiri pa ntchito yokonza valve. Kapena, wogwiritsa ntchito amatha kusankha maulumikizidwe a flanged. Chifukwa cha zosankha zonse za thupi ndi zida za diaphragm, valavu iyi imatha kugwiritsidwa ntchito pamakina osiyanasiyana.
Monga valavu iliyonse, chinsinsi chothandizira mavavu apulasitiki ndikuzindikira zofunikira zogwirira ntchito monga pneumatic motsutsana ndi magetsi ndi DC motsutsana ndi mphamvu ya AC. Koma ndi pulasitiki, wopanga ndi wogwiritsa ntchito ayeneranso kumvetsetsa kuti ndi mtundu wanji wa chilengedwe chomwe chidzazungulira chowongolera. Monga tanena kale, mavavu apulasitiki ndi njira yabwino yopangira zinthu zowononga, zomwe zimaphatikizapo malo owononga kunja. Pachifukwa ichi, zopangira zopangira ma valve apulasitiki ndizofunikira kwambiri. Opanga ma valve a pulasitiki ali ndi zosankha kuti akwaniritse zosowa za malo owonongawa monga ma actuators ophimbidwa ndi pulasitiki kapena zitsulo zokhala ndi epoxy.
Monga momwe nkhaniyi ikusonyezera, ma valve apulasitiki masiku ano amapereka mitundu yonse ya zosankha za ntchito zatsopano ndi zochitika
Nthawi yotumiza: Jul-30-2020