Pull a vacuum against a solenoid valve?

[craig1]

I have some Tyler systems that are in need of filter/dryer changes. The problem is the piping is arranged like this:

king valve>dryer>sight glass>service valve>solinoid valve.


The problem is that once I close both valves to isolate the filter, I have no access to the system. If I use the service valve for access, I will be pulling a vacuum backwards against the solinoid valve. will a solinod valve prevent reverse flow? I wouldn't think so, but maybe I'm wrong.

[Makinice]

Wouldn't front seating the service valve gain access between the king valve, drier and sightglass???

[VTP99]

Can you pump it down ?

[Dchappa21]

[jdblack]

Are you changing cores or sealed driers? Couldn't you just put in a service port while you're doing the work?

Sorry guys if none of this is relevant..... See edit

[jpsmith1cm]

You ain't gonna get a micron vacuum, but you will get most of the air out.


I think you'd be better off pumping it down as other have suggested.

[fcs]

I agree with pumping it down and/or also adding a service port

[craig1]

I can pump it down to the reciever, no problem. The problem is pulling the vacuum. neither valve provides access to the filter/drier when they're in the position that isolates the filter. I could midseat the service valve, but that would require that the solenoid can prevent backflow.

heres some pictures that I took a long time ago for another reason. If you combine what you see in the two pictures, you can figure out the piping arangement.





I'm thinking the best thing to do might be to just braze a schraeder fitting right into the liquid line between the two valves.

[Makinice]

Too bad they don't make liquid line driers with access ports.

I've pulled many a vacuum against a liquid line solenoid valve with out any problems. I don't recommend, but it's surely been done before.

Is it possible to just front seat the suction valve on the compressor once you pump it down??? If not, I'd do like you say, and install a valve in the liquid line.

[pauls heating &]

just sweat in an acess tee

[tombeaux]

I would pull the charge and make the neccesary changes / improvements as needed . ( Old tymers used to say,,,Work on it as if one day you will again and you will always make a wise decision).

[indy2000]

front seat king valve, pump the liquid line down to say, 1-2 psig, change filter then evacuate. I don't see your problem.

If you feel the compressor valves will leak, front seat the suction service valve.

Again, unless i'm missing something, you don't have an issue there.

[craig1]

front seat king valve, pump the liquid line down to say, 1-2 psig, change filter then evacuate. I don't see your problem.

If you feel the compressor valves will leak, front seat the suction service valve.

Again, unless i'm missing something, you don't have an issue there.

If I do it that way, It would require pulling a vacuum on 150 feet of 5/8 liquid line and 1 3/8 suction line, plus some huge evaps. Not something I would look forward too, especially since 4 systems need the work done.

I think I'm just gonna attempt to pull a vacuum against the solinoid valve, and if it doesn't work, braze in an access tee and pull the vacuum from that