Sostituzione Valvola 4 Vie

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Direttamente dal testo «REFRIGERATION & AIR CONDITIONING TECHNOLOGY» di Whitman, Johnson, Tomczyk e Silberstein, sesta edizione, pag. 1074 e ss.

Per prima cosa l'autore si riferisce alla brasatura della valvola:

It is even harder to heat three connections together while assembling the new valve. Torch manufacturers make tips with multiple flame heads that may be more suited for this job.

Poi si passa alla sommaria descrizione di come è fatta la valvola e dei problemi legati alla sua brasatura nel circuito (in particolare la temperatura e la possibilità che lo straccio bagnato possa veicolare umidità all'interno del circuito):

Remember, inside the valve body there is a sliding piston. It slides on a nylon pad that has a low melt-ing temperature. The valve body must be kept as cool as possible, particularly when installing the new valve. The valve body can be kept cool enough by a heat sink paste or by a wet rag wrapped around the valve body while it is being brazed in. Water can actually be dripped on the rag while the connection is being heated

If the wet rag option is used, make certain that no water is allowed to enter the piping, as this will pose problems later on. Avoid pointing the torch directly at the valve, as damage to the component can result.

Infine l'autore ci fa notare come la rimozione della vecchia valvola possa lasciare residui di cui occorre tenere conto:

When removing a defective four-way valve, it is often better to cut the piping back far enough with a tubing cutter and just have additional pipe stubs brazed in the system. You can get a clean installation this way and could actually braze the stubs into the four-way valve in the vise where you can control the heat much better. If the old valve is removed by using one of the specialty torch tips without cutting the valve stubs back, cleaning up the old stubs that will be put back into the valve will be an important task. All of the old braze filler material must be removed before the old stub will insert back into the valve.This silver braze filler material is hard to remove. It must be filed off and the pipe must have something in it to prevent the filings from entering the piping. When the piping is still in the system, it is difficult to clean up these stubs correctly.

[Scavir]

Si Ciao a Tutti,

SI SI claro che SI,

Io l'unica valvola di espansione che ho sostituita in un Gruppo Frigor o se preferite CHILLER, ho sissaldato la vecchia e sostituita senza tante precauzioni, nemmeno lo straccio bagnato.

Sebbene fosse la Prima volta che usavo un Cannello e che la valvola fosse Dietro al Compressore, in una posizione Infame, ci sono riuscito e Funziona Senza Nessuna perdita.

Che sia Fortuna ????

RiCiao,

Virginio