Evacuation Procedures

[Husky250]

Hi everyone,
Im looking for advice for evacuation procedures for long piping runs on large commercial ductless equipment. Sizes of system range from 3 ton- 24 ton. I need all the information I can get. My background is in small equipment. I want my first experience of installation to go smooth. Thanks for any input you guys can give me.

[Brian_UK]

Try searching this site for some of the many discussions on evacuation procedures.

Here's one to start with..

http://www.refrigeration-engineer.com/forums/showthread.php?t=9449&highlight=evacuation

Basically a proper triple evacuation will get you off to a good start, exactly like your present method of working, we hope ;)

[MechAcc]

Use two vacuum pumps. One at each end of the system. Might make the evacuation go faster.

[Husky250]

I agree with the triple evacuation. I also use the 1.5-2.0 psi OFN flow while brazing. I ve heard some discussion regarding making it faster in regards to gauge hoses being up-sized, schraders being removed. Any other tips you guys could give woulld help. Desired micron level? Ive been told 500 microns. Do you guys do a standing pressure test? Does it need to hold overnight? Thanks for the input!

[taz24]

I agree with the triple evacuation. I also use the 1.5-2.0 psi OFN flow while brazing. I ve heard some discussion regarding making it faster in regards to gauge hoses being up-sized, schraders being removed. Any other tips you guys could give woulld help. Desired micron level? Ive been told 500 microns. Do you guys do a standing pressure test? Does it need to hold overnight? Thanks for the input!


Sounds like you got it about right to me.
If the pipes a purged with OFN and then a good tripple vac carried out you won't go far wrong.
As for the depth of vac I would aim for about 15torr first 10 torr second 4 torr last, the last vac should be as low as possible so aim for 2 torr.
I would advise regular checks of the vac pump oil and replacement at regular intervals as well.

Cheesr taz.

[Husky250]

Thanks alot !