Vacuum time

Hi there,

In EN378-2000 Part 2 is mentioned vacuum procedure according to pressure. About time it says according to the system complexity.

Does anyone know a written standard or good practice guide which indicates the time required for vacuum?

Cheers

Do you mean time after system is reached desired vacuum level or total time of evacuation process?

Hi Nike123,

I mean total time of evacuation process.

Cheers

Quote:

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Originally Posted by lana

Hi Nike123,

I mean total time of evacuation process.

Cheers

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Total time depend on vacuum pump capacity, ambient temperature, system volume and amount of moisture in system.
That is lots of variables and it is clear that total time could not be given in meaningful manner.
On the other hand, vacuum level is clearly indicated by pressure in system and vacuum process is easily monitored with micron gauge, and determination of its success is done by controlling pressure rise after system reached some acceptable vacuum level and vacuum pump isolation after that.

Here is some time guide:
http://farm4.static.flickr.com/3583/...4cc631_o_d.png

Thanks Nike123,

The link you provided is not clear. I only see this sign. http://farm4.static.flickr.com/3583/...4cc631_o_d.png
Would you please write it.
Thanks a lot.

Cheers

Quote:

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Originally Posted by lana

Thanks Nike123,

The link you provided is not clear. I only see this sign.
Would you please write it.
Thanks a lot.

Cheers

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What is your browser?
Try use proxy server.
Probably your ISP block some pages.

Check this document:
http://www.civisec.org/guides/everyones-guides

250 microns is the figure flung round the industry. Go and get yourself a micron meter. On large ac installations (VRV) I do my first vac with a 3/8 hose with the schraders removed from the system. Then break the vac with 410A then do the same process. Then on the last vac i put the schraeders in the system. This is a very effective way to get the micron reading right down where you want it.

Thanks I got the link somehow :off topic:.


Cheers

Quote:

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Originally Posted by jbomba

250 microns is the figure flung round the industry. Go and get yourself a micron meter. On large ac installations (VRV) I do my first vac with a 3/8 hose with the schraders removed from the system. Then break the vac with 410A then do the same process. Then on the last vac i put the schraeders in the system. This is a very effective way to get the micron reading right down where you want it.

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That seems to be going against all the rules or is it different in NZ ?

Has anyone heard of treble evacuation procedures, as in breaking each stage with oxygen free dry nitrogen, Vacuum pumps flow rates are important as well. Bigger systems isolated into actual sections and dealt with individually. The final check is standing and holding vacuum rise checks plotted to determine leaks or moisture as per graph earlier posted.
Whacking down a small volume system with a high flow vac pump can also create issues, as moisture can freeze under rapid vacuum. So sits there as a lump of ice, accurate vacuum analyses are critical. Leave all connected to system for integrity and tightness/ sealed. I personally preferr copper as opposed to flexible hoses to ensure sealed system and accuracy.

in my training days it was scavenge,evacuate,charge,run,blow off r12.scavenge,evac,charge,run,blow off.charge,scavenge,evac,charge and leave.that was a triple evacuation method by the best compressor manufacturer in the world in them days