valco fittings
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Valco Instruments Co. Inc. Sales:
800–367–8424
Fax: 713–688–8106
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Introduction
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Figure 2
ID restriction
in common compression fitting
Figure 3
No ID restriction
in Valco compression fitting
Figure 4
a. Tubing seats correctly at bottom of detail
b. Tubing doesn’t reach bottom of detail,
introducing dead volume
c. Tubing reaches bottom of detail before
ferrule seats
Interchangeability
Valco fitting details are designed with
a consistent pilot depth, permitting
reliable interchangeability as con-
nections are revised or fittings are
replaced. This interchangeability
extends throughout the Valco and
Cheminert fitting and valve product
lines. Indeed, the Valco standard has
been so widely copied that Valco and
Cheminert fittings are, in general,
fully interchangeable with those
of our major competitors. In initial
installations, Valco ferrules will often
improve other manufacturers’ fitting
connections.
Because of variations in tubing OD
and in pilot and taper designs from
manufacturer to manufacturer, the
amount of tubing extending beyond
the made up ferrule can vary. (The
most radical variation is in the fittings
manufactured by Waters. Based on
the old Swagelok design, they have
a pilot depth considerably longer
than standard.)
Figure 4a
shows a
properly made up fitting. If that same
fitting is installed in a detail which
was designed for a slightly longer
tube extension (as in
Figure 4b
), dead
volume will be introduced. In the
opposite case, with the pilot shorter
than the pilot depth (
Figure 4c
),
the tube will bottom out before the
ferrule has sealed. However, our tests
prove that except in the most extreme
cases, a Valco ferrule will “creep” on the
tubing until it reaches the bottom of
the ferrule taper, making a proper seal.
Reliably Clean
Most of our state of the art CNC
machines use water-based lubricants.
After each part comes off the
machine, it is cleaned with water-
soluble detergents and then rinsed
in hot deionized water. Finally, every
metal fitting that we make is given
a thorough cleaning with steam
from deionized water at 140°C. Any
critical parts processed with oil-based
lubricants are baked to remove all
traces. The practical result of the extra
effort is this: you don’t have to be
concerned about solvent residues.
CHROMalytic TECHnology Pty Ltd AUSTRALIAN Distributors e-mail:
Tel: 03 9762 2034
