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(More customer reviews)First let me say that I own several vacuum gauges, but this is the newest and best I have. I got it in an on-line auction, New In Box, for a low price. My first use was with a 36,000 BTU/H compressor change-out on a residential package unit. Here are my observations:
Glendale AZ has an altitude of about 1110 feet. Atmospheric pressure should be about 730mm Hg but the unit self-calibrates to exactly 760,000 micrometers Hg (microns) at startup. Therefore I must assume if the sensor is linear in performance there will be 4% margin of error, and if the sensor is absolute at 0 microns then the error will be diminishing as pressure decreases. Either way, I expected to pump down below 400 micrometers Hg and hold for 15 minutes.
I flowed dry Nitrogen through the system service ports while silver brazing the compressor connections, then closed the vent and raised the Nitrogen regulator to 250psig -- closed off the valve and held constant pressure for 30 minutes to verify system integrity. I vented Nitrogen down to 1 atmosphere or zero psig and connected a Mastercool MSC 90066 5cfm vacuum pump to 3/8" hose on the Imperial Eastman (equivalent to Imperial 644-C) manifold gauge set. I installed the vacuum sensor on the 1/4" flare port of the vacuum pump (would have preferred a service port on the unit but needed both of those). Schrader valves were removed from the service ports using Yellow Jacket 18975 tools, but the side port was not connected to the vacuum probe because I had reservations that this could expose the new tool to oil foam during evacuation of the nitrogen.
As evacuation started the electronic gauge beeped to signal activity. Progress was pretty fast to below 1000 microns. Slowing near 500 microns, then very slow down to 320 microns. I wanted to close off the vacuum pump valve but this resulted in immediate jump back to 1000-1200 microns. Appears the shut-off valve is leaking in the packing nut. I repeated this action, opening and closing the vacuum pump valve and the leak was reduced and vacuum held steady at 400 microns for several minutes.
Overall I was very pleased. The unit could be enhanced with a tee instead of the bent connector, and include the 69067 ball valve at this price.
Click Here to see more reviews about: Yellow Jacket 69075 SuperEvac LCD Vacuum Gauge HVAC
Yellow Jacket 69075 SuperEvac LCD Vacuum Gauge HVAC
Click here for more information about Yellow Jacket 69075 SuperEvac LCD Vacuum Gauge HVAC
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