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Re: Gauges

Posted By: bill's neon
Date: Wednesday, 24 April 2013, at 1:39 a.m.

In Response To: Re: Gauges (SVP Neon Equipment)

> Thanks for your comments, Bill. I appreciate
> you expressing your feelings. I'll make a
> note of that.

> BTW, how do you know the gauge is accurate?
> 95% of neon vacuum gauges that are more than
> 2-3 years old (sometimes less) are out of
> calibration for various reasons. When is the
> last time it was calibrated (a true
> calibration by someone who knows what they
> are doing)? Televac recommends once every
> year. How do you know the gauge tube isn't
> contaminated and giving a false reading?
> It's easy to check if you know how, but if
> you don't you are still just guessing.
> Someone can also "tweak" the
> calibration to show a lower reading than the
> actual pressure. Many neon shops do this
> unknowingly by "resetting" the
> needle zero set. In other words, if the
> gauge isn't showing what they want it to, or
> what they think it should, they adjust the
> needle set screw until it shows what they
> want it to. Doing that does NOT calibrate
> it, but rather gives the viewer a false
> reading. Your mention of "I borrowed a
> ol' Transco Televac 2 from a friend"
> indicates the latter may be the case. A
> mechanical pump alone rarely gets as low as
> 2 microns in the real world, whereas a
> system with a properly functioning diffusion
> pump will get substantially below that
> point. So a 2 microns reading is in the
> range of "It doesn't add up".

> Best regards,
> Mark

Hi Mark, I was away from this site for a wile... Im running a welsh 1402 mechanical pump and a EGL up flow diffusion pump, and yes, i don't know when that gauge was calibrated.. so not sure how accurate it was. Is your gauge still for sale?

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