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JoeP88
28-04-2012, 07:41 PM
Hi guys, I recently purchased a analogue 'torr' gauge as my digital one seems to be playing up.

8884

mine is the one of the left, I was just a bit confused on reading it as from what I can see it goes up in 10s? and if so I've just wasted my money buying a very inacurate gauge.

any light on reading this?

aramis
28-04-2012, 08:50 PM
Accurate enough for AC applications, you need to get to half the last Torr, only marginal for refrigeration applications (0.2 Torr) and no good to test vacuum pumps.

Good thing is it won't run out of batteries on Sunday night when you must finish your work on Monday at 7AM!

Tesla
29-04-2012, 01:54 AM
Hi JoeP88
The above gauges are only good for an old centrif that uses a low pressure refrigerant like R11. They are not accurate enough at the lower end of range to measure a vacuum suitable for evacuating a system. 1000 microns and below is the range to measure.

Grizzly
29-04-2012, 10:00 AM
Hi Joe.
Sadly what the guys are telling you is correct.
Basically you have purchase a vacuum gauge with way to large a scale.
The more practical ones start at say 40torr or even 20 torr to Zero.
So basically I would use your one to observe the pressure drop then use the above to monitor the deep Vacuum.
Whilst in a deep vac you want to be able to observe small movements of pressure to help diagnose what is going on.
Your gauge is not wasted as I say it can be used to help prove the initial negative pressure drops.
Which can help when evacuating larger systems.
There is nothing worse than the initial doubts as to whether everything is leak tight.
So your gauge is not wasted, just not quite accurate enough to cover all the bases.
Grizzly