Ukukhethwa kwezinto kubalulekile ukuqinisekisa ukuthembeka kweevalvu zokufika kwiinkqubo zokukhusela umlilo. I-Brass kunye nebronze, ii-alloys ezimbini ezisetyenziswa kakhulu, zibonisa iimpawu zomzimba ezahlukeneyo kunye neempawu zokusebenza.

• Intsimbi yobheduAyinakumelana kakhulu nokugqwala, ithambile kakhulu, kwaye ihlala ixesha elide, nto leyo eyenza ukuba ibe lukhetho oluhle kakhulu kwiindlela ezifana neevalvu ezithe tye kunye neevalvu ezilawula uxinzelelo.
• Ibronzi, nangona ikwamelana nokugqwala, inemibhobho ephezulu kunye nokuqina okunciphileyo, okunokukhokelela ekuwohlokeni kwezinto ngokuhamba kwexesha.

Ukukhetha izinto ezifanelekileyo kubalulekile ukuqinisekisa ukuba iivalvu zokumisa umhlaba zihlala ixesha elide kwaye zisebenza kakuhle, kuquka iivalvu zePRV kunyeiivalvu ezithintela uxinzelelo, kwiimeko ezahlukeneyo zokusingqongileyo.

Izinto ezibalulekileyo ekufuneka ziqwalaselwe

• Ibhrasi ibiza kancincikwaye kulula ukuyila, ngoko ke isebenza kakuhle kwiinkqubo zomlilo zangaphakathi ezinoxinzelelo oluphakathi.
• Ibronze inamandla kwaye iyamelana nomhlwa ngcono, nto leyo eyenza ukuba ilungele iindawo ezinzima ezifana nolwandle.
• Ukukhetha izinto ezifanelekileyoKwiivalufa zokufikela, ixhomekeke ekubeni isetyenziswa phi kwaye yenzelwe ntoni ukuqinisekisa ukuba ihlala ixesha elide kwaye isebenza kakuhle.

Ukwakhiwa kwezinto zeLanding Valves

Ubhedu: Ulwakhiwo kunye neempawu

I-Brass yingxubevange eyenziwe ngobhedu kunye ne-zinc, kunye nomlinganiselo owahluka ngokusekelwe kwisicelo esicetywayo. Umxholo we-Copper uhlala uphakathi kwe-55% ukuya kwi-95%, ngelixa i-zinc yenza i-5% ukuya kwi-45%. Izinto ezongezelelweyo ezifana ne-lead, i-iron, i-aluminium, i-nickel, kunye ne-arsenic zihlala zongezwa ukuphucula iimpawu ezithile.

• Inkokeliiphucula ukusebenza kakuhle koomatshini, nto leyo eyenza kube lula ukuyibumba ithusi ngexesha lokwenziwa kwayo.
• Intsimbikwandisa amandla, okuqinisekisa ukuba izinto ziyakwazi ukumelana noxinzelelo loomatshini.
• I-aluminiyamkwayei-nickelyonyusa ukumelana nokugqwala, nto leyo eyenza ithusi lifaneleke kwiindawo ezichatshazelwe kukufuma okanye iikhemikhali.

I-Brass yaziwa ngokugudiseka kwayo okugqwesileyo, ivumela abavelisi ukuba benze uyilo oluntsonkothileyo lweevalvu zokufika. Ukumelana kwayo nokugqwala kuqinisekisa ukuqina kwiinkqubo zokukhusela umlilo, apho ukuthembeka kubaluleke kakhulu.

Ubhedu: Ulwakhiwo kunye neePropati

I-bronze yi-alloy equlathe ubhedu kunye ne-tin, apho ubhedu lumalunga ne-88% kunye ne-tin malunga ne-12%. Izinto ezongezelelweyo ezifana ne-aluminium, i-nickel, i-phosphorus, i-silicon, kunye ne-manganese zihlala zifakwa ukuphucula iimpawu zoomatshini kunye neekhemikhali.

• I-aluminiyamkwandisa amandla kunye nokumelana nokugqwala, nto leyo eyenza ubhedu lube yeyona nto ifanelekileyo kwiindawo zaselwandle.
• I-Nickelkuphucula ukumelana nokugqwala kunye nokuqina kwayo yonke indawo.
• I-phosphorusiphucula ukumelana nokuguguleka, iqinisekisa ukuhlala ixesha elide kwiindawo ezisebenzisa iintshukumo ezininzi.
• I-siliconkwayei-manganesenegalelo ekuqiniseni amandla oomatshini nasekuqineni.

I-bronze inamandla aphezulu okutyhala kunye nokumelana nokugqwala okugqwesileyo, ingakumbi kwiindawo ezinzima. Umzekelo, i-bronze ye-aluminium ye-nickel isetyenziswa kakhulu kwiindawo zeenqwelo-moya ngenxa yamandla ayo okutyhala angama-550 ukuya kuma-900 MPa kunye nokuqina kwiimeko zaselwandle. Ngokufanayo, i-bronze ephethe i-C932, enamandla okutyhala angama-35,000 PSI, isetyenziswa kakhulu kwiindawo zevalvu.

Umahluko oPhambili kwiNto eBunjwe ngayo

Umahluko phakathi kobume bethusi kunye nethusi uchaphazela kakhulu iimpawu zabo zomzimba kunye nokufaneleka kweevalvu zokufika.

I-alloy	Izinto eziphambili	Izinto ezongezelelweyo kunye nemiphumo yazo
Ibronzi	Ithusi (88%), Isinyithi (12%)	I-Aluminiyam (amandla, ukumelana nokugqwala), iNickel (amandla, ukumelana nokungcola), iPhosphorus (ukumelana nokuguguleka), iSilicon (amandla), iManganese (iipropati zoomatshini)
Intsimbi yobhedu	I-Copper (55%-95%), i-Zinc (5%-45%)	I-Lead (ukusebenza ngomatshini), i-Iron (amandla), i-Aluminiyam (ukumelana nokugqwala), i-Nickel (ukumelana nokugqwala), i-Arsenic (ukumelana nokugqwala)

I-brass inomxholo ophezulu we-zinc, nto leyo ephucula ukuguguleka kwayo kunye noomatshini bayo, nto leyo eyenza kube lula ukwenza ii-landing valves ezineedizayini ezinzima. Kwelinye icala, i-bronze ixhomekeke kwi-tin kunye nezinye izinto ukuze ifumane amandla aphezulu kunye nokumelana nokuguguleka, nto leyo eyenza ukuba ifaneleke ukusetyenziswa okufuna ukuqina phantsi koxinzelelo loomatshini.

Umahluko wobungakanani ugxininisa ngakumbi iimpawu zabo ezikhethekileyo:

Izinto eziphathekayo	Ithusi (%)	I-Zinc (%)	Itin (%)	Ezinye Izinto
Intsimbi yobhedu	57% ukuya kuma-63%	35% ukuya kwi-40%	N / A	N / A
Ibronzi	Ubhedu + Itini	N / A	N / A	I-Nickel, iManganese (izinto ezinokwenzeka zokongeza)

Ezi mahluko zigxininisa ukubaluleka kokukhetha izinto ezifanelekileyo zeevalvu zokufika ngokusekelweiimfuno ezithile zesicelokunye neemeko zokusingqongileyo.

Ukumelana nokugqwala kwiiValve zokuLanding

Ukumelana neBrass kunye nokuGqwala

I-Brass ibonakalisa ukumelana okuhle nokugqwala, ngakumbi kwiindawo apho kungachaphazeleki kakhulu kwiikhemikhali ezinobungozi okanye kwiimeko eziqatha. Umxholo wayo ophezulu we-copper wenza umaleko we-oxide okhuselayo xa ubekwe emoyeni okanye emanzini, nto leyo ethintela ukuwohloka okungakumbi. Le propati yenza i-brass ibe yinto ethembekileyo kwiivalvu zokufika ezisetyenziswa kwiinkqubo zokukhusela umlilo zangaphakathi okanye kwiindawo ezineemeko ezilawulwayo zendalo.

Ukongezwa kwezinto ezifana ne-aluminium kunye ne-nickel kuphucula ngakumbi amandla e-brass okumelana nokugqwala. I-aluminium idala umaleko we-oxide obhityileyo nohlala ixesha elide okhusela izinto ekufuma nasekuchaphazekeni kweekhemikhali. Kwelinye icala, i-nickel iphucula ukumelana nokugqwala, iqinisekisa ukuba izinto zigcina inkangeleko yazo kunye nokusebenza kwazo ngokuhamba kwexesha. Ezi mpawu zenza i-brass ibe lukhetho olufanelekileyo kwizicelo ezifuna ukuqina kunye nokukhanga kobuhle.

Ukumelana neBronze kunye nokuGqwala

Ubhedu lubonelela ngokugqwesileyoukumelana nokugqwala, ingakumbi kwiindawo ezinzima ezifana neendawo zaselwandle okanye kwiindawo zoshishino. Ukwakheka kwayo, ikakhulu i-copper kunye ne-tin, kubonelela ngomqobo wendalo ngokuchasene ne-oxidation kunye neempendulo zeekhemikhali. Ukufakwa kwezinto ezifana ne-aluminium kunye ne-phosphorus kuyomeleza ngakumbi ukumelana kwayo nokuguguleka kunye nokubola.

Uphando lubonisa ukuba i-nickel-aluminium bronze (NAB) ibonisa ukumelana nokugqwala okuphuculweyo kwiindawo zaselwandle. Olu phuculo luvela kwiimpawu zesakhiwo se-NAB/steel composite structures, ingakumbi ezo zenziwe nge-Wire-Arc Additive Manufacturing (WAAM). Ubungakanani obuncinci bengqolowa kunye nokunqongophala kwe-κ phase kwi-WAAM-NAB kunciphisa ukugqwala kwesigaba esikhethiweyo, okubangela ukusebenza okungcono ngokubanzi. Ezi mpawu zenza i-bronze ibe yinto ekhethwayo kwiivalvu zokufika ezivezwe kumanzi anetyuwa okanye ezinye izinto ezigqwalisayo.

Izinto Ezichaphazela Ukugqwala Kwindalo

Indalo idlala indima ebalulekileyo ekumiseleni ukumelana nokugqwala kwezinto ezisetyenziswa kwiivalvu zokufika. Izinto ezinje ngokufuma, ubushushu, kunye nokuvezwa kwiikhemikhali okanye kumanzi anetyuwa zinokukhawulezisa inkqubo yokugqwala. Umzekelo, ithusi lisebenza kakuhle kwiimeko ezomileyo okanye ezifumileyo kodwa linokugqwala ngokukhawuleza kwiindawo ezinetyuwa eninzi okanye ezivezwe kwi-asidi.

Ibronzi, ngokwakhiwa kwayo okuqinileyo, iyakwazi ukumelana neemeko ezinzima, kuquka iindawo zaselwandle kunye nokusetyenziswa kwemizi-mveliso. Nangona kunjalo, nebronzi inokonakala xa ivezwa kumanqanaba aphezulu e-pH okanye idibana neekhemikhali eziyingozi ixesha elide. Ukugcinwa rhoqo kunye nokukhetha izinto ezifanelekileyo ngokusekelwe kwiiimeko zokusingqongileyozibalulekile ekuqinisekiseni ukuba iivalvu zokufika zihlala ixesha elide kwaye zithembekile.

Ukuqina kunye namandla eeValve zokuLanding

Iipropati zoMbane zeBrass

I-brass ibonakalisa indibaniselwano eyahlukileyo yamandla kunye nokuguquguquka, nto leyo eyenza ukuba ibe yinto ethembekileyo kwiivalvu zokufika. Amandla ayo okutsalwa adla ngokuba phakathi kwama-200 ukuya kuma-550 MPa, kuxhomekeke kulwakhiwo oluthile lwe-alloy. La mandla avumela i-brass ukuba inyamezele uxinzelelo oluphakathi loomatshini ngaphandle kokuqhekeka okanye ukuguquguquka. Ukongeza, ukuguquguquka kwayo kuqinisekisa ukuba abavelisi banokuyibumba ibe yimizobo entsonkothileyo ngaphandle kokubeka emngciphekweni ulwakhiwo lwayo.

I-brass ikwabonakalisa ukumelana nokuguguleka okugqwesileyo, ingakumbi kwiindawo ezixineneyo. Olu phawu lunciphisa amathuba okuwohloka komphezulu ngokuhamba kwexesha, luqinisekisa ukusebenza rhoqo. Ukufakwa kwezinto ezifana nentsimbi kunye ne-aluminium kuphucula ngakumbi uzinzo lwayo loomatshini, okwenza ifaneleke ukusetyenziswa okufuna amandla kunye nokuchaneka.

Iipropati zoMbane zeBronze

I-bronze yaziwa ngamandla ayo aphezulu kunye nokuqina kwayo phantsi kweemeko ezinzima. Amandla ayo okuxinana adla ngokuba phakathi kwe-300 ukuya kwi-800 MPa, kuxhomekeke kwi-alloy. Oku kwenza i-bronze ibe lukhetho oluhle kakhulu lokusetyenziswa apho ukuqina kubaluleke kakhulu. Ukongezwa kwe-tin kunye nezinye izinto ezifana ne-phosphorus kunye ne-manganese kuphucula ukumelana kwayo nokuguguleka, okuvumela ukuba imelane nokusetyenziswa ixesha elide kwiindawo ezixineneyo.

Ibronze ikwagqwesa kakhulu kwizicelo zokungqubana okuphezulu ngenxa yokuba iphantsi kakhulu xa ingqubana. Le mpawu inciphisa ukuguguleka, yandisa ubomi bezinto ezisetyenzisiweyo. Amandla ayo okugcina ulungelelwaniso lwesakhiwo phantsi kweemeko ezinzima ayenza ibe yinto ekhethwayo kwiivalvu zokufika ezivezwe kwimithwalo enzima yoomatshini.

Ukuqina Kwexesha Elide Kwizicelo Ze-Landing Valve

Ukuqina kwexesha elide kweevalvu zokufika kuxhomekeke kubuchule bezinto zokuthintela ukuguguleka, ukubola, kunye noxinzelelo loomatshini. Uphando malunga nokuphila ixesha elide kweevalvu, njengezifundo malunga nokufakelwa kwevalvu ye-aortic ye-transcatheter (TAVI), lubonelela ngolwazi oluxabisekileyo. Umzekelo, uvavanyo lwe-PARTNER-1 lubike ukuba akukho kubola kwevalvu yesakhiwo (SVD) emva kweminyaka emihlanu, ngelixa olunye uphando lubone ukwanda kwe-SVD ye-14.9% emva kweminyaka esixhenxe. Ezi ziphumo zibonisa ukubalulekaukukhetha izinto ezinokuqina okuqinisekisiweyokwizicelo ezibalulekileyo.

I-Brass kunye ne-bronze zombini zibonelelaukusebenza okuhlala ixesha elide xa kusetyenziswakwiivalvu zokufikela. Nangona kunjalo, ukhetho phakathi kwezi zimbini luxhomekeke kwisicelo esithile kunye neemeko zokusingqongileyo. I-brass ifanelekile kwiindawo ezixineneyo nezilawulwayo, ngelixa i-bronze igqwesa kwiindawo ezixineneyo okanye ezirhabaxa. Ukukhethwa kwezinto ezifanelekileyo kuqinisekisa ukuthembeka kunye nobude bexesha leevalvu zokufikela kwiinkqubo zokukhusela umlilo.

Ixabiso kunye nokuLungiswa kweeValve zokuLanding

Uthelekiso lweendleko: I-Brass vs. Bronze

I-brass kunye ne-bronze zahluke kakhulu kwixabiso ngenxa yokwakheka kwazo kunye nokufumaneka kwazo. I-brass, eyenziwe kakhulu yi-copper kunye ne-zinc, idla ngokuba nexabiso eliphantsi. Ukusetyenziswa kwayo ngokubanzi kwimibhobho kunye nokusetyenziswa kwemizi-mveliso kunegalelo kwixabiso layo eliphantsi. I-bronze, equlethe i-copper kunye ne-tin, idla ngokubangela iindleko eziphezulu ngenxa yokunqongophala kwe-tin kunye nee-alloys ezikhethekileyo ezifunekayo kwizicelo ezithile.

Abavelisi badla ngokukhetha ithusi kwiivalvu zokufikela xa ukusebenza kakuhle kweendleko kuyinto ephambili. Ithusi, nangona libiza kakhulu, linika amandla aphezulu kunye nokumelana nokugqwala, nto leyo eyenza ukuba libe lolona khetho lukhethwayo kwiindawo ezinoxinzelelo olukhulu. Isigqibo phakathi kwezi zinto sixhomekeke ekulinganiseni imida yebhajethi neemfuno zokusebenza.

Izinto ekufuneka ziqwalaselwe xa kusenziwa umatshini kunye nokuveliswa kwawo

Ubuchule bokuchwetheza budlala indima ebalulekileyo ekumiseleni ukuba lula ukwenza iivalvu zokufika. Ibrass ibonisa ubuchule bokuchwetheza obuhle kakhulu ngenxa yokuba ithambile kwaye inobunzima obuphantsi. Le propati ivumela abavelisi ukuba bavelise uyilo oluntsonkothileyo olungenazo izixhobo ezisetyenzisiweyo. Ibronzi, nangona ihlala ixesha elide, inika imingeni emikhulu ngexesha lokwenziwa kwayo ngenxa yobunzima bayo obuphezulu kunye namandla okutsala.

Le theyibhile ingezantsi igxininisa imilinganiselo ephambili yobuchule bokusebenza kwe-bronze kunye ne-bronze alloys:

Uhlobo lwe-alloy	Amandla okuThamba (ksi)	Amandla okuVuna (ksi)	Ukwandiswa (%)	Ubunzima (uBrinell)	Ubuchule bokusebenza (YB)
Ubhedu Olubomvu	83	N / A	32	N / A	35
I-Manganese Bronze	86	90	45	48	30
I-Bronze yeTin	90	40	45	21	30

Amanqaku aphezulu eBrass okwenza ukuba ikwazi ukusebenza kakuhle ayenze ifaneleke kakhulu kwiimfuno ezifuna ukuchaneka nokusebenza kakuhle. Ibronze, nangona ikwazi ukusebenza kakuhle, ihlala iyindlela efanelekileyo yokufikelela kwiivalvu zokufika kwiindawo ezifuna amandla amaninzi ngenxa yamandla ayo oomatshini.

Iindleko zoLondolozo kunye noBomi

Iindleko zokugcinwa kunye nomjikelo wobomi zixhomekeke ekuqineni kwento kunye nokumelana nokuguguleka kwayo. I-brass ayifuni ukugcinwa rhoqo kwiindawo ezilawulwayo, nto leyo enciphisa iindleko zexesha elide. Nangona kunjalo, kwiimeko zokugqwala okanye zoxinzelelo oluphezulu, i-bronze inika ixesha elide elingcono, inciphisa iindleko zayo zokuqala eziphezulu ngokunciphisa ukuphindaphinda kokutshintshwa.

Ukukhetha izinto ezifanelekileyo zeevalvu zokufika kuqinisekisa ukusebenza kakuhle ngelixa kunciphisa iindleko zizonke. Abavelisi abafana neYuyao World Fire Fighting Equipment Factory babeka phambiliiinkcukacha zezinto ezibonakalayoukubonelela ngezisombululo ezithembekileyo nezingabizi kakhulu kwizicelo ezahlukeneyo.

Usetyenziso kunye nokufaneleka kweeValve zokuLanding

Iivalvu zokuHlala zeBrass: Izicelo eziqhelekileyo

Iivalvu zokumisa zebrass zisetyenziswa kakhulu kwiindawo apho uxinzelelo oluphakathi loomatshini kunye neemeko ezilawulwayo zilawula khona. Ukumelana kwazo nokugqwala kunye nokuguquguquka kwazo kuzenza zilungele iinkqubo zokukhusela umlilo zangaphakathi, njengezakhiwo zorhwebo, iindawo zokuhlala, kunye neendawo zeeofisi. Ezi valve zisebenza ngokuthembekileyo kwiinkqubo apho ukuvezwa kwiikhemikhali eziqatha okanye imozulu embi kuncinci.

Ukulula komatshini wokwenza ithusi kuvumela abavelisi ukuba bavelise uyilo oluntsonkothileyo, nto leyo eyenza ukuba ilungele iivalvu ezilawula uxinzelelo kunye neevalvu ezithe tye. Ukongeza, iivalvu zokumisa ithusi zihlala zikhethwa ngenxa yobuhle bazo, njengoko zigcina inkangeleko ekhazimlayo ngokuhamba kwexesha. Olu dibaniso lomsebenzi kunye nomtsalane obonakalayo lwenza ithusi libe lukhetho olukhethwayo kwizicelo ezifuna zombini ukusebenza kunye nokuguquguquka koyilo.

Iivalvu Zokumisa I-Bronze: Izicelo Eziqhelekileyo

Iivalvu zokuhlamba zebronze zibalaseleyo kwiindawo ezifuna amandla apho ukuqina kunye nokumelana nokugqwala kubalulekile. Ukwakheka kwazo okuqinileyo kuzenza zilungele iinkqubo zokukhusela umlilo zangaphandle, izakhiwo zoshishino, kunye nokusetyenziswa kolwandle. Ezi valve zimelana noxinzelelo oluphezulu loomatshini kwaye ziyamelana nokuguguleka, nokuba kwiimeko ezinzima ezifana nokuvezwa ngamanzi anetyuwa okanye amaqondo obushushu aphezulu.

Amandla aphezulu eBronze kunye neempawu zokungqubana eziphantsi zenza ukuba ifaneleke kwiinkqubo zoxinzelelo oluphezulu kunye nezicelo ezinzima. Umzekelo, iivalvu zokungenisa ibronze zisetyenziswa kakhulu kwiindawo zokubeka iinqanawa, kumaqonga aselunxwemeni, nakwizityalo zeekhemikhali. Ukukwazi kwazo ukunyamezela iimeko ezinzima kuqinisekisa ukuthembeka nokhuseleko lwexesha elide kwiinkqubo zokukhusela umlilo ezibalulekileyo.

Ukukhetha Izinto Ezifanelekileyo Kwiimfuno Ezithile

Ukukhetha izinto ezifanelekileyo zeivalvu yokufikakuxhomekeke kwiimfuno zesicelo kunye neemeko zokusingqongileyo. I-brass lukhetho oluhle kakhulu kwiindawo zangaphakathi okanye ezixinezelekileyo ngenxa yokuba ifikeleleka lula, iyakwazi ukusebenza kakuhle, kunye nokumelana nokugqwala. Ngokwahlukileyo koko, i-bronze ifanelekile ngakumbi kwiindawo ezixinezelekileyo okanye ezirhabaxa, apho amandla nokuqina kubaluleke kakhulu.

Abavelisi abanjengoYuyao World Fire Fighting Equipment Factoryzibonelela ngoluhlu lweevalvu zokufika ezenzelwe ukusetyenziswa okwahlukeneyo. Ukuqonda iimfuno ezithile zenkqubo yokukhusela umlilo kuqinisekisa ukukhethwa kwezinto ezifanelekileyo, okuphucula ukusebenza kwevalvu kunye nobude bayo.

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I-Brass kunye ne-bronze zahlukile ngokubunjwa, ukumelana nokugqwala, ukuqina, kunye nexabiso. I-Brass inika ukufikeleleka kunye nokusebenza kakuhle, ngelixa i-bronze igqwesa ngamandla kunye nokuqina. Ukukhetha izinto ezifanelekileyo kuxhomekeke kwiimeko zokusingqongileyo kunye neemfuno zokusetyenziswa. Ukuqonda iinkcukacha zezinto kuqinisekisa ukuba ii-landing valves zisebenza ngokuthembekileyo kwaye zihlala ixesha elide kwiinkqubo zokukhusela umlilo.

FAQ

Zeziphi izinto eziphambili ekufuneka ziqwalaselwe xa ukhetha phakathi kweevalvu zokumisa ubhedu kunye neevalvu zobhedu?

Vavanya iimeko zokusingqongileyo, uxinzelelo loomatshini, kunye nohlahlo lwabiwo-mali. I-Brass ifanele iindawo ezilawulwayo, ngelixa i-bronze igqwesa kwiindawo ezixinezelekileyo okanye ezirhabaxa.

Ukumelana nokugqwala kwahluka njani phakathi kwebrass kunye nebronze?

I-brass iyamelana nokugqwala kwiimeko eziphakathi. I-bronze inika ukumelana okuphezulu, ingakumbi kwiindawo zaselwandle okanye kwimizi-mveliso, ngenxa yokwakheka kwayo okuqinileyo.

Ngaba iivalvu zokumisa intsimbi yebrass zibiza kancinci kunezebronzi?

Ewe, ibrass idla ngokuba nexabiso eliphantsi ngenxa yokwakheka kwayo kunye nokusebenza kwayo. Nangona kunjalo, ukuqina kwayo kunokunciphisa iindleko zokutshintshwa kwexesha elide kwizicelo ezifuna amandla.