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AC guys. Pulling a vac and knowing what’s happening.

What’s a good read to get more training on pulling a vac vs pump size vs bouncing numbers and such? I have a great leak free setup and do well (90 microns if I get distracted) but like to know it all.
Thanks.
Thanks.
Just a guy running some pipes.
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Comments
One thing to remember is, the size of your vacuum hoses has much more to do with the speed of vacuuming than the size of the vacuum pump. And just because you have a good vacuum at one end of the system doesn't mean the vacuum is good at the other end. Air movement is extremely sluggish and slow moving under deep vacuums.
ramermechanical.com
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A micron gauge is a heater and a thermocouple, the rate of heat transfer is dependent on the vacuum in the system. You can see how that would be really skewed by oil contamination!
Not about "oil contamination" but about bad readings, and then claiming micron gauges are useless junk.
Keep the sensor pointed up to at least attempt to keep oil out of it, and then make sure it's kept clean.
they also have a cleaning video if they become contaminated with oil, you have to clean them 6-12 times, another thing I didn't know
Over the long week end I tested the lineset and coil with 300PSI.
Held for about 72 hours.
The outside coil is pretty beat up from hail, checked it several times.
Was doing the vacuum pump on line set. I always do the triple.
First time was down to about 2000 microns. A little N2 flush and vac again. Wouldn't go below 3200. Turned the indoor blower on thinking warming the basement coil might help.
Still 3200, shut pump off and microns climbed to 4000..5000 and eventually atmospheric.
Added N2 up to 150 psi, you could hear the leak in the coil inside the case. One of the distributor tubes leaking as it went into the 3/8 tube of the coil.
I have never had this happen before. Hold 300 psi that long and then not hold vacuum. I believe when I turned the blower on the vibration loosened the joint. However the blower was on constantly during the 72 hour 300 psi test.
I guess this was a hit and miss leak situation.
O well, next week it gets a complete new system.