welcome to this Swagelok video today's
topic is considerations in managing the
supply pressure effect of a regulator
for lower flow applications an
alternative method of regulating supply
pressure effect is to use two-stage
pressure reduction this can be
accomplished by using two single stage
regulators installed in series or the
two regulators may be combined into one
assembly to calculate the variability of
outlet pressure for a two-stage
regulator setup the inlet pressure
difference is multiplied by the SPE of
each regulator as illustrated in the
following equation
the first-stage regulator controls the
inlet pressure variation to some degree
while the second-stage regulator
controls it further together the two
regulators bring the outlet pressure
very close to the target we will use a
kcy model regulator and return to our
supply pressure effect example the
cylinder empties from 172 bar to 34 bar
or 2500 psi g2 500 psi G assume that
each regulator has a 1% SPE with a 137
bar or 2000 PSI G inlet pressure drop
the first stage regulator will
experience a 1.3 bar or 20 psi G
increase in outlet pressure as a result
of that increase the second stage
regulator will experience a 0.01 bar or
0.2 0 psig decrease in outlet pressure
the net result is a minimal pressure
decrease that is only 0.01 percent of
the initial cylinder pressure drop 0.01
bar or 0.20 PSI G equals 137 bar or 2000
PSI G times 0.1 times 0.1 once the
cylinder pressure drops below the first
stage setting in this case 34 bar or 500
psi G or the SPE of this regulator is no
longer applicable and only the SPE of
the second stage regulator is taken into
account then the assembly will behave
like a single stage regulator
notice how the effect on the outlet
pressure is lessened from the previous
regulator Arrangements applications that
require a gas cylinder supply multiple
operations with at least one operation
requiring a different pressure you will
need to use two-stage regulation the
first stage regulator will be located
near the gas source and a second stage
regulator located on each of the process
lines be sure to avoid the costly
mistake of using a two-stage regulator
at the gas supply source and a single
stage regulator at the point of use this
setup is equivalent of three stage
regulation
with the regulator controlling outlet
pressure from a gas cylinder supply
pressure effect is a phenomenon that
will always be present whenever there is
a change in inlet pressure there will be
a corresponding change in outlet
pressure you can minimize the effects of
supply pressure effect for many
applications by using a single regulator
with a balanced poppet design or by
using a two-stage regulator but if your
gas source is servicing multiple
operations with different pressure
requirements you may need multiple
single stage regulators one near the gas
source and another on each process line
to an effect provide two-stage
regulation at each point of use refer to
swagelok.com in the product literature
for additional information thank you for
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