Opis izdelka:
Vrvica iz mikrovlaken
Cena: Cena nihajnega povratnega ventila se spreminja zaradi specifikacij, stroškov materiala in menjalnega tečaja. Prosim, da mi sporočite svoje kontaktne podatke, posodobil vam bom najnovejšo ceno
Kako deluje protipovratni ventil?
Razpočni tlak
A Swing Check Valve requires a minimum upstream pressure (pressure differential between inlet and outlet) to open the valve and allow flow through it. This minimum upstream pressure at which the valve opening occurs is called the check valve 'cracking pressure'. The specific cracking pressure changes based on the valve design and size, so ensure that your system can generate this cracking pressure and that it is suitable for the application.
Zapiranje
Če predhodni tlak kdaj pade pod tlak razpok ali obstaja protitlak (tok se poskuša premakniti od izstopa proti vhodu), se ventil zapre. Glede na zasnovo povratnega ventila se lahko zapiralni mehanizem spremeni. Skratka, protitlak potisne vrata, kroglo, diafragmo ali disk proti odprtini in jo zatesni. Glede na zasnovo lahko postopek zapiranja pomaga vzmet ali gravitacija.
Usmeritev namestitve
Ker enosmerni ventil deluje samo v eni smeri, je ključnega pomena, da poznate pravilno orientacijo namestitve. Pogosto je na ohišju ventila puščica, ki signalizira smer pretoka. V nasprotnem primeru boste morali pregledati ventil, da se prepričate, da je nameščen v predvideni smeri toka. Če je vzvratno, se tok ne bo mogel premikati skozi sistem,-zvišanje tlaka pa lahko povzroči poškodbe.
Vrste kontrolnih ventilov
Glede na zasnovo povratnega ventila bodo delovali nekoliko drugače. Najpogostejši povratni ventil je vzmetni v-protočni ventil, vendar bomo v nadaljevanju razpravljali o več vrstah.
Vzmetna v-vrstica
In-line spring loaded Swing Check Valve are common, easy to understand, and have a simple design. Figure 1 shows an example of a spring loaded in-line check valve and Figure 2 shows the main components with arrows showing flow direction. When flow enters the input port of the valve, it has to have enough pressure (force) to overcome the cracking pressure and the spring force. Once overcome, it pushes the disc, opening the orifice and allowing flow to move through the valve. When the input pressure is no longer high enough, or there is a backpressure, then the backpressure and spring push the disc against the orifice and seal the valve shut. The spring, along with the short travel distance for the disc, allows for quick reaction time for closing. This valve design also prevents against pressure surges in the line, and therefore, also prevents a water hammer from occurring. Common types of spring loaded in-line check valves are also called 'nozzle check valves' or 'silent check valves.' They can be installed in a vertical or horizontal orientation. However, since they are in-line to the system, they have to be fully removed from the line to be inspected and/or perform maintenance.
Vzmetni Y
Spring loaded y-check valves operate very similar to in-line spring loaded check valves. The difference, as you can see in Figure 3, is that the spring and movable disc are positioned at an angle. This creates a 'y' shape, hence the name of the valve. It works the exact same as an in-line valve, but since the moveable components are at an angle it can be inspected and serviced while it is still connected to the system. However, they are larger and take up more room within the system.
žoga
A ball check valve uses a free-floating or spring-loaded ball that rests on the sealing seat to close the orifice. The sealing seat is normally conically tapered in order to guide the ball into the seat and create a positive seal, thereby, stopping reverse flow. When the pressure of the fluid in the inlet side exceeds the cracking pressure, the ball is dislodged from its seat and allows flow to occur. When the inlet pressure doesn't exceed the cracking pressure, or there is back pressure, the ball will close with the back pressure or via the spring, effectively closing the orifice.
Slika 4: Vzmetni krogelni povratni ventil z vstopnim priključkom na levi in izstopnim priključkom na desni.
Diafragma
Diaphragm check valves consist of a rubber diaphragm that flexes open when the inlet pressure is increased. Normally, these types of valves have a free-floating self-centering diaphragm, which makes them normally open (NO). These means that there is no "cracking pressure", however, they can be normally closed (NC) and then it requires an inlet pressure to overcome the diaphragms elasticity. Figure 5 on the left shows a normally open diaphragm check valve as there is 'minimal' inlet pressure and the media still gets through. As inlet pressure increases, the diaphragm will flex open more allowing flow through, as seen in Figure 5 in the middle. If backpressure occurs (or it is a normally closed diaphragm check valve) the diaphragm will be forced against the opening and seal it to prevent any backflow, as seen in Figure 5 on the right. Due to the normally open nature, diaphragm check valves are ideal for low-pressure or vacuum applications.
Dvig
Dvižni povratni ventil je sestavljen iz vodenega diska, ki se dvigne (dvigne) s sedeža ventila, da omogoči pretok medija. Za premagovanje gravitacije in/ali vzmeti je potreben razpočni pritisk, vodilo pa drži disk v navpični črti, tako da je mogoče disk ponovno{0}}namestiti s pravilno poravnavo in tesnjenjem. Najpogosteje je pri dvižnih protipovratnih ventilih potrebno, da se medij obrne za 90- stopinj, kot je prikazano na sliki 6, vendar obstajajo protipovratni ventili, ki so v liniji ali pod kotom. Ko se vstopni tlak zmanjša pod tlak razpok ali pride do protitlaka, se ventil zapre z gravitacijo, vzmetjo in/ali z uporabo protitlaka. Če ni vzmeti, ki bi pomagala pri zapiranju, je orientacija pritrditve glede na gravitacijo pomembna, da zagotovite, da se bo disk zapiral s gravitacijo.
Gugalnica
Swing check valves are also commonly referred to as 'tilting-disc' check valves. They consist of a disc that is on a hinge (or trunnion) that swings open with an inlet pressure. As inlet pressure decreases or there is a backflow, the disc will swing shut. If there is no spring to assist in closing, mounting orientation in regard to gravity is important to ensure that the disc will swing shut with gravity. Figure 7 shows an example of a swing check valve.
Ustavi se
Zaporni nepovratni ventil je običajno vzmetni y{0}}povratni ventil ali dvižni povratni ventil, vendar ima funkcijo ročne preglasitve. To jim omogoča, da delujejo kot običajni povratni ventil in preprečujejo povratni tok, vendar obstaja zunanji mehanizem, ki ga je mogoče uporabiti za preglasitev in vzdrževanje ventila v odprtem ali zaprtem stanju. Zato lahko ta ventil deluje kot dva ventila v enem. Običajno se uporabljajo v elektrarnah, cirkulaciji kotlov, parnih generatorjih, hlajenju turbin, varnostnih sistemih.
Metulj ali napolitanka
Povratne ventile za metulje in nepovratne ventile za rezine je mogoče uporabljati zamenljivo. Sestavljeni so iz diska v obliki metulja ali rezin, ki je na tečaju in vzmeti. Ko vstopni tlak preseže razpočni tlak, se obe strani odpreta, kot je prikazano na sliki 9. Ko se vstopni tlak zmanjša ali pride do povratnega toka, bo vzmet na tečaju (ali protitlak) zaprla disk in ga učinkovito zatesnila. Ta tip ventila omogoča raven pretok medija z minimalnimi ovirami.
Kontrolni ventili za vodo
Povratni ventili se uporabljajo v številnih aplikacijah za vodo, kot so pitna voda in odpadne vode, in se preprosto imenujejo enosmerni vodni ventili. Za aplikacije za pitno vodo zagotavljajo, da noben medij iz okolja (izstopna stran ventila) ne more vstopiti v sistem z varno čisto pitno vodo in ga kontaminirati. Za aplikacije odpadne vode zagotavljajo, da odpadna voda ne more{0}}ponovno priti v sistem in povzročiti prelivanje ali dodatno onesnaženje. Za aplikacije črpanja vode se pogosto uporablja nožni ventil, da se zagotovi, da v cev ne pridejo ostanki, in za ohranjanje notranjega tlaka za polnjenje. Duckbill ventili se lahko uporabljajo tudi za izpuste na vodovodih. Povratni ventili črpalke zbiralnika zagotavljajo, da izpraznjena voda ne pride nazaj v črpalko zbiralnika z gravitacijo, ko je črpalka izklopljena.
Pnevmatski povratni ventil
Pnevmatski povratni ventil ali zračni povratni ventil omogoča dotok zraka in preprečuje, da bi izstopil. Pogosto jih preprosto imenujemo enosmerni zračni ventili. Najpogostejša uporaba je za zračni kompresor. Omogočajo kompresorju, da nekatere dele ohranja pod tlakom in druge dele{0}}pod tlakom. Lahko se nahajajo na batnem kompresorju (vhodni in izstopni), sprejemniku zraka, izpustni cevi itd.
Pogosto zastavljena vprašanja
Kaj je simbol povratnega ventila?
The check valve symbol can be seen in Figure 13. It points in the orientation that it allows the flow with a vertical line showing it doesn't allow backflow.
Slika 13: Simbol povratnega ventila
Kaj je namen povratnega ventila?
Glavni namen protipovratnega ventila v sistemu je preprečiti povratni tok, ki bi lahko poškodoval opremo ali kontaminira medij v zgornjem toku.
Katere so pogoste težave s povratnim ventilom?
Common check valve problems are: noise, water hammer, vibration, reverse flow, sticking, leakage, and component wear/damage. To prevent issues, it is crucial that a check valve is specified correctly for the application and media. The two most common issues due to improper specification are reverse flow and water hammer. For both issues, a fast-closing check valve should be used. Reverse flow can occur if the check valve doesn't close fast enough and water hammer can occur if pressure surges occur causing shock waves within the media.
Ali bo povratni ventil ustavil vodno kladivo?
Povratni ventil lahko prepreči vodno kladivo, če hitro deluje. To preprečuje prenapetost tlaka, ki ustvarja udarne valove po celotnem mediju. Ti udarni valovi lahko poškodujejo opremo, nosilce cevi in celo počijo cevovode zaradi vibracij.
V kakšni smeri naj bo nameščen povratni ventil?
Povratne ventile je treba namestiti v skladu z njihovim vstopom in izstopom, kar je pogosto prikazano kot puščica na ohišju ventila. Ker omogočajo pretok samo v eno smer, če so nameščeni nazaj, ne bodo delovali pravilno. Glede na vodoravno ali navpično, je odvisno od vrste zasnove ventila. Če ima vzmet, je vsaka orientacija v redu. Če ni vzmeti, lahko gravitacija vpliva na delovanje protipovratnega ventila, zato zagotovite, da poznate notranje komponente, da ga boste pravilno namestili vodoravno ali navpično.
Zakaj moj povratni ventil ne deluje?
When a check valve doesn't work, it allows backflow. Three possible reasons for this are: sticking, leakage, or slow closing. If there isn't a filter in the line, dirt or debris can be trapped between the disc and body keeping it open. Due to wear or corroding media on the material, the disc or seat can become damaged or torn preventing a proper seal and allowing backflow. If the valve closes too slow, minimal backflow can enter before a proper seal can occur. Ensure that gravity is helping the design, and/or your spring is quick enough to close the valve rapidly.
Priljubljena oznake: gugalnica preveri ventil
