Trouble with micron gauge

[jdblack]

Micron Gauge type - Yellow Jacket micron gauge 69086
Vacuum pump type - Robinair 6 CFM Vacuum pump 15601

Okay so I don't trust my micron gauge. I'm worried that it's faulty, and I don't have a back up to test it with.

Tell me what you guys think.

I've replaced the gasket and cleaned the sensor with Alcohol, and I still get the same results. I was even worried that the stem adapter was faulty so I swapped it to a 1/4" NPT - 1/4" male SAE. I can get the sensor to pull down to 10 micron on my pump but immediately after valving it off it begins to climb and climbs well over 2000 micron. I have tried using the shut valve on the pump and I have also used 2 other ball valves with new seals. I've used my manifold gauge sets to valve it off and it still climbs immediately after removing the vacuum. I have pressure tested these gauges and valves with Nitro and can not find any leaks.

Is this the sign of a faulty sensor? The unit is less then 1 year old.

[dunkman]

sounds like a leak. Maybe hose permeation. I don't trust those blank off valves. At least mine has never worked right.

[jdblack]

But I'm doing this without hoses and with multipe hoses and I get the same result. I'm just wondering what the signs are of a faulty sensor.

[dunkman]

If the sensor pulls down, it must be working. I don't think a bad sensor would pull down at all.