Ingqalasizinda

Yiziphi nokuthi ungakhetha kanjani ipompo engcono kakhulu ye-dacha

Amapompu angenakuqhathaniswa ahlukaniswa nokungahambisani nokungabi khona komsindo nokudlidliza, kanye nomkhiqizo ophakeme.

Lolu khetho luyashesha, lukhuni futhi lukhulu kakhulu luzokwazi ukukunikeza ngamanzi ukusuka emthonjeni kwanoma yikuphi ukujula.

Okulandelayo, sizoxoxa ngamapompo angaphansi komhlaba angatholakala emakethe, yiziphi izici okufanele uziqaphele nokuthi yini intengo incike kuyo.

Izinhlobo eziyinhloko zamapompu angaphansi komhlaba: yikuphi okungcono?

Cabanga ukuthi yiziphi izinhlobo zamapompo angaphansi komhlaba, ukuthi ahluke kanjani nokuthi iyiphi indlela engcono yokuthenga esimweni esithile.

Vibrating

Zilula ngokusetshenziswa nokugcinwa kwamapompo, okubonakala ngokuphila komsebenzi okwandisiwe.

Isimiso sokusebenza. Ukukhuluma kahle, idivayisi isebenza njengamapayipi ethu, lapho amafomu okucindezela okungakapheli ngesikhathi sokungafihli, ngenxa yalokho sithola umoya kithi. Kuhlangene, le ndima yenziwa insimu yamagnetic kanye nenhloko, lapho isebenza khona. Ingqikithi ibangela imfucumfucu ye-rubber egobayo, ekwakheni ukucindezelwa okubi phakathi kwedivayisi. Emva kwalokho, i-liquid iqala ukugeleza ngokukhululekile ngaphakathi kwepompo, eliyidlula ngamapayipi phezulu. Ukuze uqinisekise ukuthi i-current ejwayelekile, iziphethu ezikhethekile zifakiwe ngaphakathi, ezibuyisela umdwebo endaweni yayo yasekuqaleni.

Izinzuzo:

  • intengo ephansi;
  • ukuhlala;
  • izindleko zokugcina eziphansi.

Umthengi:

  • ukuxhomekeka kwamanzi ukugeleza emotheni kwinethiwekhi (ngisho nokungafani okuncane okuholela ekunciphiseni okukhulu ekusebenzeni kahle);
  • iphakamisa umsila kusukela phansi ngoba umphumela wokudala izidakamizwa;
  • ayikwazi ukusetshenziswa emithonjeni emincane.

Kubalulekile! Ukujula kokujula okuphezulu kunama-50 m.

Isikulufa

Idivayisi engasebenza ngisho nangamanzi angcolile kakhulu.

Isimiso sokusebenza. Ngaphakathi kwedivayisi kukhona isikrini esikhulu sokuvunguza esizungeze intambo yangaphakathi. Emva kokuqala isikulufa siqala ukushintshanisa njengendlela yokugqoka ekhoneni noma epunch. Ngenxa yalokho ukuhamba, amanzi aqala ukukhuphukela phezulu, emva kwalokho aphethwe emgqeni.

Izinzuzo:

  • ukungcola okuhle akukwazi ukuvimbela ukusebenza kwepompo;
  • isici esijikelezayo sande amandla;
  • Ukucindezelwa kwamanzi akuxhomekile ekuvinjeni kokujikeleza kwesikrini.

Umthengi:

  • ubukhulu obukhulu bedivayisi;
  • Ukusebenza kahle (65%);
  • ukusebenza kuncike ebude be-screw, ngakho-ke ukunyuka okukhulu emanzini amaningi angenayo kuyadingeka ukushintsha idivayisi.
Kuzosiza futhi ukuba ufunde ukuthi ungakhetha kanjani umshini wokushisa oshisayo, isibani sezimbali zasendlini, ukukhipha insiza ye-hose yokunisela, indlela yokukhetha inqola engadini noma inqola, indlela yokukhetha i-timer yokunisela, i-sprinkler yokunisela, isibani sesithombo, indlela yokwenza u-chopper kagesi amagatsha ngezandla zabo.

I-Centrifugal

Ilula ngokulandela ukusebenza kanye nenhlobo ekhiqizayo kakhulu yeyunithi. Amapompo ase-Centrifugal afakiwe hhayi kuphela ukuhlinzeka ngamanzi, kodwa futhi ukudala okwamanje ukushisa izinhlelo.

Isimiso sokusebenza. Ngaphakathi kwedivaysi, i-injini ifakiwe, lapho ama-blades axhunyiwe ngokuqondile. Ngemva kokuqala, ama-blade aqala ukuhambisa, okwenza kube nengcindezi encane, eholela ekusondeleni kwezansi. Emva kwalokho, amanzi ahamba ngenxa yamandla we-centrifugal, ekhuphuka. Ukuze uthole amandla aphezulu, faka izikuluzi eziningana ngama-blades okusheshisa ukugeleza kwamanzi.

Izinzuzo:

  • ukusebenza kahle (ngaphezu kwama-85%);
  • angaphuma amanzi ngisho nasemithonjeni yobuciko;
  • babe nobukhulu obuncane.

Umthengi:

  • ukuthembela emotweni njalo kwinethiwekhi;
  • ukusebenza kahle kuncike ezingeni lamanzi.

Ukugubha

Uhlobo lwepompi ye-centrifugal enamandla awo.

Isimiso sokusebenza. Into yomsebenzi yilevili elinezindlela eziningi ezincane. Isondo lixhunywe injini bese lifakwa ebhokisini le-cylindrical. Ngesikhathi esifanayo igebe eliphakathi kwezindonga nevili lingenalutho. Okubalulekile ukuthi ngisho nangamanzi amancane angena kudivayisi, kuncike ingcindezi enkulu ngokwanele evumela amanzi ukuba asuswe ekuphakameni okukhulu.

Izinzuzo:

  • ukusebenza kahle;
  • ukuba khona kwengcindezi eqinile, kungakhathaliseki ukuthi umthamo wamanzi;
  • ubukhulu obuncane;
  • ikhono lokusebenza ezinzulu kakhulu.

Umthengi:

  • noma iyiphi i-debris ikhubaza ngokushesha i-unit;
  • ukuhlukahluka akuthandwa kakhulu, ngakho kwezinye izifunda kunzima ukuwuthola.
Funda futhi ukuthi ungakhetha kanjani isitimela sokuphampa ukunikeza, indlela yokwenza uhlelo lwamanzi kusuka emthonjeni endlini yangasese.

Yini okufanele ubheke uma ukhetha ipompo: ukucaciswa kobuchwepheshe

Cabanga ngezici eziyinhloko zobuchwepheshe okufanele zicatshangelwe ngenkathi kukhethwe idivayisi.

Imfanelo yamanzi

Ngenhla, sishilo ukuthi ezinye izinhlobo zamaphampu ziqala ukudiliza ngenxa yamanzi angcolile. Kulesi simo, akukhona ukuthi idivayisi idonsela kusiliva nasesihlabathini kusukela phansi, kodwa mayelana nokuthi kunendaba engakanani emisiwe ikholomu yamanzi.

Uma uqiniseka ukuthi amanzi emthonjeni wakho unyaka wonke uyobe ehlanzekile ngokwanele, khona-ke kufanele unikeze ukukhetha ukuhluka kwe-centrifugal noma i-vortex. Kodwa-ke, uma uketshezi olunamakhemikhali amaningi, kungcono ukuthenga inguqulo yokucwiliswa kwesikulufa.

Ngokwehlukana, kufanele kushiwo ngamapompu okudlidliza. Awonawona okhethweni olungcono ngisho nangamanzi ahlanzekile, ngoba ngenxa yomsebenzi adala ukudlidliza, ngenxa yokuthi ingezansi isithutha.

Ukufakwa kwabo kuphakanyiswa kuphela uma izindonga kanye nomthombo wezansi zihlanganiswa nokuqashwa kwamatshe, okungavumeli izinhlayiya ezinhle ziqhume phansi.

Uyazi? Ipompo yokuqala yaqalwa eGrisi ku-II-Ikhulu BC. U ... Wayephethe ama-cylinders amabili, ahlome ama-valves kanye ne-lever yokulawulwa kwe-manual. Leli yunithi yayisetshenziselwa ukuqeda umlilo, okwenza kube negama elithi "Umlilo Wase-Alexandria."

Ukusetshenziswa kwamandla

Inani lamanzi anikezwa ngehora ngokuqondile kuxhomeke ekusebenziseni amandla - amandla amaningi, amamitha ayi-cubic ngaphezulu. Kodwa-ke, kufaneleka ukukhumbula ukuthi uhlobo ngalunye lwedivaysi lusebenza kahle, ngakho-ke ipompo ye-centrifugal izokhipha amandla amancane ngenkathi isebenza futhi isikhunta esisodwa, nakuba amandla azo azoba okufanayo.

Kufanelekile ukunaka lesi sici, ngaphandle kwalokho uzothola inqwaba ezodla amandla amaningi, kodwa ukukhiqiza kwayo kunganeliseki izidingo zakho.

Khumbula ukuthi izingxenye ezimbalwa ezihambayo ngaphakathi kwedivayisi, uzothatha ugesi ophansi. Isibonelo, ukonga kakhulu kuyipompo yokudlidliza, ngoba akukho lutho olukuyo ngaphakathi, kodwa ludala kuphela insimu yamagnetic esebenza engqondweni.

Futhi ngaphakathi kwe-screw version kukhona i-screw enkulu ye-iron, ukushintshaniswa kwayo okuthatha umthamo omkhulu kagesi.

Inhloko enkulu

Eqinisweni, sikhuluma ngokuphakama noma ibanga elingakanani le unit linganikeza amanzi.

Uhlobo ngalunye lunokucindezela okungcono nokuphezulu, okungukuthi, ibanga lapho i-unit inikeza amanzi ngesivinini esivamile.

Ukucindezela akuxhomeke kuphela emandleni edivaysi, kodwa futhi ekujuleni kwe-dive, nakumkhawulo womthombo osuka endlini, ngakho-ke kubalulekile ukuthatha zonke izinto eziguquguqukayo ukuze zithole ipompo kanye namandla.

Uma udinga ukuthola ukucindezela okukhulu, njengoba umthombo unokujula okukhulu noma ukude nomuzi, kufanele ukhethe ukuhlukahluka kwe-vortex, okuzohlinzeka ngokucindezela okukhulu.

Kungase kube usizo kuwe ukwazi ukwakha ikamelo elingaphansi kwegalaji, ukwenza isitofu saseDutch, ukwenza isiteji noma isitebhisi-isinyathelo, ishaja ehlobo ukunikeza ngezandla zakho siqu, ukwenza isilifa nge-pallets, isivakashi phezu kwesikhumbuzo, ukwakha ibhuku izindlela zokukhonkolo, indlela yokwenza isitofu-ngezitovu ngezandla zakhe, indlela yokukhetha itanki le-septic ukunikeza.

Uma umthombo ungajulile noma usondelene namaphuzu asetshenziswayo ezindlini, amanzi ahlukeneyo asetshenziswayo.

Ukucindezela okukhulu futhi okunamandla kwedivayisi kuboniswa ngaso sonke isikhathi ngencazelo yayo. Kumele kucatshangwe ukuthi lokhu akukhona kuphela ngokujula komthombo, kodwa mayelana nebanga ukusuka epompo kuya emanzini okusetshenziswa kwamanzi.

Ibuye ihlose iphutha ngendlela yokulahlekelwa kwengcindezi ngenxa yokunyakaza kwamanzi, izinga lamanzi emthonjeni, ububanzi kanye nezinto ezibonakalayo zepayipi, ukuphakama kwesakhiwo, nobude bamapayipi asezingeni eliqondile nelinembile.

I-Bandwidth

Ngamanye amazwi, amandla edivaysi, inani lomkhuhlane elingakwazi ukupompa isikhathi ngasinye.

Lapho ukhetha ipompo, umbuzo uphakama ukuthi amanzi adliwa ngakanani ngehora noma ngosuku. Bala lesi sibalo kunzima, ngakho kufanele ubale inani elilinganiselwe, bese ufaka iphutha.

Ukusetshenziswa okujwayelekile kwamaphuzu amakhulu okuhlinzeka ngamanzi:

  • ikhishi - kufika ku-500 l / h;
  • hlamba isitsha - kuze kube ngu-60 l / h;
  • ukugeza - kufika ku-500 l / h;
  • indlu yangasese - kuze kube ngu-50 l / h;
  • okugeza noma i-sauna - kuze kufike ku-1 000 l / h;
  • ukuphuzisa insimu / ingadi - amamitha ayi-cubic amane amanzi ngalunye isikwele.

Ungakwazi futhi ukwakha izinga lokusetshenziswa kwamanzi ngosuku ngosuku lomuntu ngamunye, okungama-200 amalitha.

Kubalulekile! Ungakhohlwa ngamadivayisi ahlukahlukene adla amanzi. Kufanele futhi zicatshangelwe ngesikhathi sokubala.
Kubonakala ukuthi endlini encane noma indlu, lapho umndeni owodwa ohlala khona u-3 uhlala khona, kukhona okwanele ipompo, okuzokhiqiza cishe ngamamitha ayi-cubic 3-4 amanzi ngesikhathi samahora amaningi.

Ukujula ukujula

Ukujula kokujula kuhlobene ngokuqondile nomfutho wamanzi, ngakho-ke lezi zinkomba ezimbili kufanele zicatshangelwe ngesikhathi esisodwa. Kufanele futhi ukukhumbula ukuthi emithonjeni ejulile, kusetshenziselwa ukuhlukahluka kwe-vortex noma i-centrifugal kuphela, okuhloswe ngezinhloso ezinjalo.

Izikhombisi eziningi zepompo e-submersible zihlobene, ngakho-ke akufanele uthenge i-unit nge-margin enkulu, ngaphandle kwalokho kuzothinta intengo.

Isibonelo, uma idivaysi ihloswe emithonjeni ejulile noma ama-boreholes, khona-ke iyoba namandla amaningi futhi idle inani elikhulu lamandla, futhi idinga amavolumu angu-380 volts.

Lolu khetho luzokwazi ukuphakamisa amanzi kusuka ezingaphezu kwamamitha angu-300, nokunikeza ikhanda elihle, kodwa intengo izoba ngamashumi ezinkulungwane. Ngenxa yalesi sizathu, akudingekile ukuba uthathe ipompo ngokujula kokugcwiliswa kokugcina. Ngeke ukwazi ukujulisa kahle, futhi izindleko ezijwayelekile zikagesi zokusebenza kweyunithi zizoholela enani elikhulu.

Futhi cabanga ukuthi ipompo kufanele ifakwe endaweni ephakeme okungenani ngamamitha angu-150 ukusuka phansi. Ngokuphathelene nemithombo ejulile, i-unit akufanele ihlehliswe endaweni engaphezu kuka-10 m ukusuka emanzini.

I-hydraulic tank umthamo

Igama lesibili - i-hydroaccumulator, noma ithangi lokunweba. Kubalulekile ukugcina ingcindezi enhle ohlelweni lwamanzi.

Ibuye ivikeleke ngesinamanzi samanzi, inikeza amanzi amancane lapho ipompo ivuliwe ngenxa yezizathu ezithile, futhi ixwayisa ukuthi idivayisi ihlale ivuliwe uma kudingeka inani elincane lemanzi.

Umthamo omncane we-tank yokwandisa cishe ulingana nama-25 amalitha.. Lezi zibhamu zisetshenziselwa amaphampu aphansi-amandla, kanye nokusetshenziswa kwamanzi nsuku zonke. Izidingo kanye namandla amaningi wedivayisi, umthamo omkhulu we-tank hydraulic.

Indlela engcono kakhulu yokuhlinzeka indawo yokuhlala encane emkhayeni owodwa uhlala yitangi lama 30-50 amalitha.

Abaningi bakhathazekile ngombuzo wokuthi kungani ungathengi amathangi amakhulu kakhulu. Iqiniso liwukuthi uma amanzi ehlala ethandeni isikhathi eside futhi engasetshenzisiwe, ikhwalithi yayo iqala ukuwohloka. Into efanayo eyenzeka ngamanzi emiphongolweni evaliwe lapho i-oksijini ivaliwe.

Uma ufuna ukuba ne-tank enkulu yamanzi uma kwenzeka ukuqhuma kwamandla okungalindelekile, ungathenga ngokuqonda kwakho, noma kunjalo, uma kungekho ukuhluleka kwamandla, gcina amanani amaningi we-accumulator.

Uma ungeke ukwazi ukuthi ungakanani umuthi owudingayo, kungcono ukuxhumana nomdayisi. Ochwepheshe bazokwazi, ngesisekelo solwazi mayelana neyunithi ethile, ukubala umthamo omkhulu we-accumulator njengendlela yefomula.

Khumbula ukuthi ivolumu yethangi ithinta kuphela ukutholakala ketshezi kanye nemvamisa yokushintsha ipompo. Lesi sici singabizwa ngokuthi umgodi owakhelwe ngaphakathi, lapho amanzi ekhona ngaso sonke isikhathi, kanti ngesikhathi esifanayo akunakwenzeka ukwenqaba i-hydroaccumulator.

Uyazi? Ngo-1911, e-UK, kwadalwa ipompo eyasusa amanzi ngaphandle kwengcindezi yegesi ekhishwe ngesikhathi sokushisa kwamanzi abizayo. Kulokhu, umqondo wokuklama okunjalo wenziwa phambili ekuqaleni kwekhulu le-XVIII.

Izici ezengeziwe

On amayunithi abizayo submersible efakwe izinzwa ezahlukene eziqinisekisa ukuvikelwa ezimweni ezingalindelekile. Le divayisi yokugcwalisa ikuvumela ukuba ukhohlwe ngokuhlola okuvamile komsebenzi, kanye nokusebenzisa ipom ezindaweni ezikude.

Kodwa-ke, amadivaysi ashibhile akakwazi ukuziqhenya ngokuba khona kwemisebenzi enjalo, ngakho-ke kubalulekile ukwazi ukuthi yikuphi ukuvikelwa okumelwe kunikezwe epompo.

Dry running. Lona ukusebenza kwepompo ngezinga elinganele lamanzi noma lingekho. Umsebenzi onjalo ungakhubaza le divayisi emahoreni ambalwa. Isizathu siwukushisa komshini, kanye nokungqubuzana kwengxenye ehambayo. Amanzi angena ngepompo enza imisebenzi emibili ngesikhathi esisodwa: ipholisa futhi iyancipha ukuxabana, ngakho-ke, uma engekho, amaphampu anamandla angashisa.

Ukuze uvimbele ukusebenza okumile, ukuvikelwa okukhethekile kufakwe epompini, okungabiza kakhulu njengepop ngokwayo. Ukuvikelwa okunjalo kuyadingeka uma, nganoma yisiphi isizathu, awukwazi ukuhlola njalo izinga lemanzi noma izinga lokugeleza kwalo lwenziwa kumshini (ukuzithelela okuzenzakalelayo kwendawo).

Ngenxa yalokho, kunezinketho ezimbili: ukuthenga iyunithi ebiza kakhulu ngesistimu eyakhelwe ngaphakathi noma ukuthenga ukuvikelwa ngokwehlukana.

Ukuvikelwa ekusebenzeni okumile kungagcwaliswa ngezinzwa ezikhethekile noma ikhasi elivamile, okufana nalo okutholakala endishini yangasese. Ukhetho lwesibili lungabizi, kodwa owokuqala ikuvumela ukuba ulawule kangcono izinga lamanzi ngokucisha idivayisi kusengaphambili.

Ukushisa kakhulu. Kuvela ngenxa yokugijima okomile, noma ngenxa yokuphuma kwamandla. Esikhathini sesibili, ukuvikelwa kokusebenza okumile ngeke kulungise isimo, ngenxa yalokho idivayisi izohluleka. Ngenxa yalesi sizathu, amaphampu amaningi avikelelwa ngokumelene ne-voltage and overheating.

Ukuvikelwa okunjalo kungaba normalizes wamanje noma uvala ucingo.

Ngeke ukwazi ukuthenga ukuvikelwa ngokweqile ngokweqile, ngakho-ke uma lo msebenzi ubalulekile kuwe, khona-ke kufanele uqale ukhethe iphompo elisezingeni eliphezulu.

Uma lokhu kungenakwenzeka, bese ukhathazeka ngomlawuli we-voltage, owondliwa epompo ukuze idivayisi ingaboni.

Ipompo elingaphansi komthombo: sikhetha umenzi

Cabangela abakhiqizi abakhulu basekhaya nabangaphandle bezimpompi ezingaphansi komhlaba. Ukutshela mayelana nokungafani kwamanani nekhwalithi.

Ngaphandle kwezwe

"Dab"Izwe - i-Italy.

Lezi amaphampu ezihlakaniphile ezihamba phambili ezinemisebenzi ehlukahlukene ewusizo ukuqinisekisa ukuthi ukusebenza okungaxhunyiwe okuphazamiseka kwedivayisi. Ihluke ekubaleni kokugcina, ukusebenza okuthula, futhi akudingi i-tank yamanzi. Idivayisi enamandla ngokwanele enezinga elihle.

"Omnigena"Izwe - i-Poland.

Amayunithi ale nkampani ahluke emisebenzini ekhethekile, kodwa anezindlu ezinhle, ezinganqamuki, ezenziwe ngethusi nensimbi engagqwali. Amapompi asebenza kahle futhi kulula ukulondoloza.

"Grundfos"Izwe - iDenmark.

Imikhiqizo yekhwalithi ephezulu kakhulu esebenza isikhathi eside. Amayunithi alula ukuyisebenzisa, ngakho ngeke kube nezinkinga ekuhlanzeni noma esikhundleni sezingxenye. Ngalokhu konke, intengo yamaphampu inkulu, okumele icatshangelwe.

Ekhaya

"I-Jilex"

Imikhiqizo inezinga eliphezulu kakhulu lentengo-ukusebenza, yingakho ithola ukuthandwa kakhulu. Amadivayisi afakwe izinzwa ezidingekayo ezikuvumela ukuba uzisebenzise ezindaweni ezikude. Ukufakwa akuyona inkimbinkimbi, amaphampu asebenza cishe ngokuthula, ngakho angafaniswa ngekhwalithi namadivayisi angaphandle.

Kubalulekile! Ayikho i-valve yokuhlola emapompu.
"I-Technoprobe"

Imikhiqizo yenkampani inexabiso eliphansi futhi, ngenxa yalokho, ithandwa kakhulu. It ingathengwa cishe zonke izingxenye zezwe. Amapompi awanakho ukugcwaliseka kwanamuhla futhi awunayo izinga eliphansi lomsindo, kodwa kulula ukulondoloza, futhi uma kwenzeka ukuphazamiseka, ukulungiswa kuyoba kubiza kakhulu.

"Belamos"

Достаточно недорогая продукция хорошего качества, которая используется для поднятия воды со значительной глубины. Насосы работают даже в мутной воде без регулярной очистки. Цена полностью соответствует качеству.

Погружные насосы помогают обеспечить беспрерывную поставку воды в дом или на участок, при этом не перегреваются и не шумят так сильно, как непогружные варианты. Ngokukhethwa kahle kwepom ngeke ube nezinkinga ngesikhathi sokusebenza.

Impendulo evela kubasebenzisi benethiwekhi

Ngangivame ukuba yisikhathi sonke seManzi Cannon, ngoba mina ngilisebenzise ngokuphumelelayo iminyaka engaphezu kwemihlanu. Futhi wamdlwengula ngaphandle kukaNkulunkulu. Kodwa maduzane kunezikhalazo eziningi mayelana ne-Water Cannon, nakuba zingenakho amaqiniso akhonkolo, uqala ukubuza abantu mayelana nokusebenza kwepom, kepha ngokuvamile abaphenduli.
Leo-ilanga
//www.mastergrad.com/forums/t140450-pogruzhnoy-nasos-dlya-kolodca-posovetuyte/?p=2481371#post2481371

I-Grundfos ayinangqondo kakhulu ekukhuleni kokuqukethwe kwesihlabathi. Kule ndaba, amathonti ethu amnandi amanzi kanye ne-Dzhileksy. Konke okunye, i-Grundfos ayinakho ukuncintisana. Awu, ngaphandle kwemali.
I-Maestro
//forum.rcdesign.ru/f56/thread141674.html#post1274477

Ngesikhathi sokugcina ngifaka amaphampu e-Dzhileks-Vodomet angaphansi komhlaba, awekho amaphampu ajwayelekile, kuze kube yi-pritenzy. Ukuzenzekelayo kuyinto efiselekayo ukusebenzisa kusukela kuDanfos njengoba inesimo esicacile esicacile nesibonayo esibaluleke kakhulu. Ngokuqondene nodada lomgodi, kufanele uyenze noma kunjalo, kungenzeka ukuthi awukhulu kakhulu kodwa konke okufanayo.
I-Interso
//www.stroimdom.com.ua/forum/showpost.php?p=1560987&postcount=2