<VV> Vacuum modulator valve/line vacuum test

[FrankCB at aol.com]

Stephen,
    30 in Hg VACUUM is a perfect vacuum (actually it's  29.92 in Hg, but 
that's close enough).  So without going into lots of other  dimensions (using 
string theory?) you can't get a better VACUUM than that  which is equivalent to 0 
psia absolute pressure.  45 psi doesn't make sense  as a VACUUM reading.  If 
it's a pressure reading, then 45 psiA is  about 3 times atmospheric pressure, 
while 45 psiG is about 4 times atmospheric  pressure.
    This is undoubtedly why boost gauges show boost  pressure as "psig" while 
also showing intake manifold VACUUM  as "in. Hg"
    Frank Burkhard 
 
In a message dated 7/31/2007 7:22:21 PM Eastern Daylight Time,  
contactsmu at sbcglobal.net writes:

Next  problem ; my gauge measures in Hg vac or the corresponding   
kpa.  I want to be able to convert to psi which the table on  7-55  
shows.  After doing a little research, I found that: "One  standard  
atmosphere equals 14.7 psi (29.92 in.-Hg)".  If that  is true, and I'm  
not missing something - yeah, right - then I would  never be able to  
use this indicator to measure the vacuum pressure  as the dial, which  
measures from 0-30 Hg vac/ (about) 100  Kilopascals or kPa, would run  
out of dial after about 14  psi.   My lowest reading, other than 0 in  
R and N would be  45 psi and I would need to be able to obtain  
measurements in excess  of 100 psi for the L position check.
Sorry for the questions,  but I've researched the Service manual, the  
operation booklet that  came with the Mityvac and the web and I'm  
still at a loss.
What am I missing here?

Stephen Upham
Dallas,  Texas
Corvaireum //







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