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<DIV>Hi Larry:</DIV>
<DIV> </DIV>
<DIV>Perhaps some clarification is needed regarding what pressure is
where. I have no problem adjusting the supply regulator for the
venturi to produce the required 40 inches of water vacuum when using the
standard 55 psi supply. However, my air distribution system outside
of the machine is higher pressure. </DIV>
<DIV> </DIV>
<DIV>My approach, whether for a single machine or multiple machines, is to have
the compressor (with tank, filters, etc. sized
accordingly) supplying high pressure to the machine(s) location and
have a regulator installed on the input to each machine which adjusts and
regulates the pressure to 55 psi where it enters the machine. So the path
is: hi-pressure into the regulator, then 55 psi out split to: 1) venturi supply
regulator, and 2) a check valve. The venturi supply regulator
reduces the 55 psi to whatever pressure is required to generate the 40 inches of
vacuum. Meanwhile, on the other side of the 55 psi split, the
output of the check valve goes to the pressure interlock switches, the
internal reservoir tank and the head bearing.</DIV>
<DIV> </DIV>
<DIV>Very interesting what you said about the RCA machines increasing the guide
vacuum during wind. I didn't know that. Most of my RCA experience
was TRT-1B and a little TR-22. After that, almost all Ampex except for a
few minor encounters.</DIV>
<DIV> </DIV>
<DIV>Don Norwood<BR>Digitrak Communications, Inc.<BR><A
href="http://www.digitrakcom.com">www.digitrakcom.com</A></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=leodham@centurylink.net href="mailto:leodham@centurylink.net">L.E.
Odham</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=quadlist@quadvideotapegroup.com
href="mailto:quadlist@quadvideotapegroup.com">Quad List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Saturday, June 02, 2012 10:34
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [QuadList] Ampex Quad VTR
Airflow Requirements</DIV>
<DIV><BR></DIV>
<DIV
style="FONT-FAMILY: verdana,helvetica,sans-serif; COLOR: #000000; FONT-SIZE: 12pt">
<P>Ditto.</P>
<P>I seem to recall that when we updated the Ampexes at the station I worked
at, we had to run the air supply up to 80 psi in order to get the venturis to
reliably produce 70 in., and then adjust it down to 40 in. vacuum with a
norgren regulator valve. That gave some reserve vacuum supply for
adjustment,variation,etc.</P>
<P>Also on the RCA machines, it had to be 80 psi because there was a valve
soleniod that engaged during rewind placing 100 in. vacuum on the guide.</P>
<P> </P>
<P>my 2 cents,</P>
<P>larry</P>
<P> </P>
<P>LE Odham</P>
<P>Engr/Tech</P>
<P>TAMIS Archive</P>
<P>Knoxville, Tenn.<BR><BR></P>
<P>
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