Line regulators have a lower allowable inlet pressure (typi-
cally 300psi) and must never be attached directly to a gas
cylinder. Line regulators are used to further reduce the
pressure of a gas from the supply line to that required at the
point of use. Line regulators are always single-stage regula-
tors, and may be equipped with a single pressure gauge to
indicate outlet pressure. (See page 25 for regulators.)
Oxygen, moisture, and elastomeric contaminants can migrate
through rubber or elastomeric diaphragms and enter the
carrier gas. Therefore, all regulators should incorporate metal
(Teflon@ coated stainless steel) diaphragms to assure that
contaminants will not enter the gas line. Consult Table II to
determine the proper type and size of cylinder valves as
described by the Compressed Gas Association (CGA)
numbers for each regulator.
Table II - High Purity Two-Stage Regulators
Proper type and size of cylinder valves:
/I
When installing any
regulator, be sure to use
high qualityTeflon@ tape
on allmachine thread
connections, DO NOT
use Teflon tape on
Swagelok-type compres-
sion fittings.
Wind Teflon tape clockwise
to ensure a good seal.
High Purity Two-Stage
Regulator (CGA 580):
cat.#
20606
High Purity Single-
Stage Regulator:
cat.#
20609
MINICYL General Purpose
1/8"Regulator:
cat.# 20610
Flexible Pigtails
Pigtails (cat.# 20615) are commonly
installed between the two-stage regula-
tor and the gas lines. They allow the
necessary flexibility in removing
regulators from the cylinder. Pigtails are
constructed of braided stainless steel
with an inert Teflon core.*
Flexible
pigtails
make it easier to change gas cylinders.
*
Some 02
and
moisture will diffuse
through the
Teflon core
stainless steel
braided
pigtails. Always use oxygen and moisture traps downstream
of
flexible pigtails.
Tubing
The next step in plumbing GC gases
to the instrument is choosing the
appropriate tubing size.Most GCs are
plumbedwith l/s” bulkhead fittings,
therefore l/8” tubing is commonly
used. The location of the gas cylin-
ders also determines if a larger
diameter tubing is required between
the tanks and the GC. If only one GC
is being plumbed from tanks located
in the same room, 1/8" tubing is sufficient. However, if the
tanks are located outside the room or if several GCs are being
plumbed from the same source, 1/4" tubing is recommended to
reduce pressure drop in the line and supply adequate gas for
several instruments.When using 1/4" tubing, plumb theGC
with a1/4" line from the tanks to back of theGC. Then use a
1/4 to1/8" female reducer (cat.# 21825) to allow attachment to
the first purifier. Connect both purifiers to the carrier gas line
with1/8" tubing loosely coiled.Whenmeasuring the 1/8"
tubing, provide extra length to coil the tubing into shock
loops. Shock loopswill prevent instrument vibrations from
being transferred to the supply lines and loosening fittings or
breaking gas purification traps. Additionally, shock loops
allow an instrument to bemoved on the lab bench. Complete
the installation by plumbing1/8" tubing from the outlet of the
last purifier to the GC bulkhead fitting.
6
6
1998
