Inficon PGE500, Operating Manual

Page: 34 / 84

34
5 Using the
A thermal cond
on the thermal
Since different
ductivities, the
be different. IN
mal conductivit
When a gas ot
for the differen
and the gas in
indicate how di
an INFICON co
WARNIN
gases other tha
death or seriou
manual when m
For N
2
the calib
dicated and tru
1000 Torr. At p
the different ga
these low pres
between therm
At pressures a
diverge signific
currents in the
loss from the s
geometry and
Generally, air a
thermal conduc
ences in readin
ing a system to
change by 30 t
gradually displa
the effect is mu
ous condition a
e gauge with
ductivity gauge se
conductivity of th
gases, and mixtu
indicated pressur
NFICON convectio
ty gauges) are ca
her than N
2
/ air is
ce in thermal cond
use. The charts a
ifferent gases affe
onvection gauge.
NG! Using a ther
an that for which i
us injury. Be sure
measuring pressu
bration shows exc
ue pressure throug
pressures below 1
ases are similar. T
sures is a constan
mal conductivities o
bove 1 Torr, indic
cantly. At these hig
gauge become th
sensor and calibra
mounting position
and N
2
are consid
ctivity, but even N
ngs at higher pres
o atmosphere usin
to 40 Torr after the
aces the N
2
in the
uch more significa
as described below
tinb
h different ga
enses heat loss wh
e gas surrounding
ures, have differen
re readings and ou
on gauges (and mo
librated using nitro
s used, correction
ductivity between
and tables on the f
ect the display and
mal conductivity g
t is calibrated cou
to use gas correc
res of gases othe
cellent agreement
ghout the range fr
Torr, the calibrat
The difference in re
nt, a function of th
of the gases.
cated pressure rea
gher pressures co
he predominant ca
ation depends on g
n as well as gas pr
ered the same wit
N
2
and air will exhib
ssures. For examp
ng N
2
, you may se
e chamber is open
e gauge. For most
ant and may result
w.
b21e1 (2016-06)
ases
hich depends
g the sensor.
nt thermal con-
utputs will also
ost other ther-
ogen (N
2
).
must be made
nitrogen (N
2
)
following pages
d output from
gauge with
uld result in
tion data in this
r than N
2
/ air.
between in-
om 10
-4
to
ion curves for
eadings at
he difference
adings may
onvection
ause of heat
gauge tube
roperties.
th respect to
bit slight differ-
ple, when vent-
ee readings
ned and air
other gases
t in a hazard-