Alstom FKG1X - Page 85

Description and operation
SF
6
gas
monitor
ing
M20
-
-0
02EN03
6/10
02--2011
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ion contained in
this document is indicative only. No
representati
on or
warrant
y is
given or should
be
relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial circumstances. It is
provided without liabili
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is subject to
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en authority, is
strictly prohibited.
 GRID
Measuring density
Pressure units
D
The internationa
l unit pressure is
the Pascal (Pa), and
hectopa
scal (hPa)
used for
atmosphe
ric pressure
measur
ements.
D
The practical unit is the bar (14.503 p.s.i.)
1
b
a
r
=
1
0
0
0
h
P
a
=
1
4
.5 ps
i
1
b
a
r
=
1
0
0 kP
a
1
0 ba
r
=
1 MP
a
D
Standar
d atmospheri
c pressure is eq
ual to 1,013
hPa at sea level and an
air temperature of 20
°
C (68
°
F).
Measuring density
 Wh
en
it
is
no
t
po
ss
ib
le
to
di
re
ctl
y
me
as
ur
e
de
ns
ity
,
thi
s
maybe
ch
ec
ke
d
us
ing
an industrial pressure gauge capable of measuring the
effective pressure
.
An effective pressu
re value corres
ponds to the rated density
, determined for
normal atmosphe
ric pressure (1,013
hPa) and an ambient temperature of
20
°
C (68
°
F).
For
eac
h
pre
ssu
re
rea
din
g
(fill
ing
,
ins
pec
tion
of
den
sime
ter
thre
sho
lds...)
,
the
rated effective pressure should be corrected according to the ambient tem-
pe
ra
tur
e
an
d
atm
os
ph
er
ic
pr
es
su
re
of
the
sit
e
at
the
tim
e
theread
in
g
is
tak
en
.
The real pre
ssure is the
refore
:
P
real
=
P
rated effective in accordance with temperature
+
Δ
Pp
*
*
Δ
Pp
:
correction in accordance with atmospheric pressure
.