thinking of buying a micron gage

[jasond1011]

I am finally after many years considering buying a micron gage. am i correct in assuming that a leaky line set will not produce a 500 micron vacuum due to the leak and can help diagnose leaks in in accessible lines? Can i use the micron gage to isolate the lines and coil and achive a 500 micron vacuum to insure i'm not putting a new condensor or compressor on a leaky system? In a typical scenario how long would it take the 500 mic vacuum to bleed down if i had a leak? I know these are simple questions, but i haver never used vacuum to diagnose leaks, only long term nit pressure tests and electronic leak detectors, etc. thanks Any recommendations on brands and types? we are res light commercial dealer, mostly ac heat pumps and some light refrigeration when we can't get out of it.

[mark beiser]

The function of a micron gauge is to insure you are getting all the moisture and non condensables out of a system, not leak checking.

The pressure differential is to small for good leak checking, you wouldn't pressure test a system at only 14.7psi would you?
Not to mention that you can have a leak that won't show up in a vacuum because something is getting sucked against the leak when under a vacuum.

I personally recommend the Yellow Jacket 69075 vacuum gauge.
http://www.yellowjacket.com/HVACRPro...&l=2&c=16&p=55

[hvacbear]

Get one that works and you are confortabel with. You need this tool!
Supco makes an economical durable unit. Make sure you follow the directions for placement and cleaning.

[nineball]

Yellow Jacket 69075 vacuum gauge..... Great vacuum guage!

Like someone said above, vacuum guages should not be your resource for finding leaks. Do a standing pressure test.. But on the other hand sometimes your vacuum guage will help confirm a leak even very small leaks.

My own findings using vacuum guages.. If the system will hold below 800 microns with the pump off you dont have any leaks possible moisture in the system at this reading. If it holds below 500 you are leak free and moisture free.. Im sure you wont find that in any book

[alpha480v]

In my opinion, a micron gauge is one of the most important tools you have in your arsenal. Ya Got to make sure that moisture is out of the system!