DH Instruments PG7000, Руководство по эксплуатации и обслуживанию

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7. 10BAPPENDIX
Page 209 © 1998-2008 DH Instruments, a Fluke Company
7.2.3 FLUID HEADS
7.2.3.1 FLUID HEAD COMPONENTS
PG7000 supports three different fluid head components (see
Sections 3.11.3, 3.9.7): DUT head, ATM head and Piston head. The three
components are combined to create the overall head correction for each PG7000
measurement mode (see Section 7.2.3.2).
DUT head: Calculates and applies a fluid head correction to predict the defined
pressure at a level other than the PG7000’s reference level (see Section 3.9.7).
The DUT head is calculated following:
( )
D a f H
gh P
DUT
ρ ρ
− =
Where:
DUT
H
P
, DUT head [Pa] = fluid head correction applied to the defined pressure
calculated at the PG7000 reference level.
ρ
f
, fluid density [kg/m
3
] = density of the pressurized medium (oil density = 916 kg/m
3
,
water density = 998.2321 kg/m
3
, gas densities are calculated
for N
2
, He or air dependent on current pressure and
temperature).
ρ
a
, air density [kg/m
3
] = density of ambient air calculated using current ambient
pressure, temperature and relative humidity (values as
specified in the active SETUP file, see Section 3.10).
Assumed to be zero when operating in absolute with a
vacuum reference mode. Calculated using static pressure
density measured by RPM in PG7601 differential mode.
g ,
gravity [m/s
2
] = acceleration due to gravity (value as specified in the active
SETUP file, see Section 3.10).
h
D
, DUT height [m] = Height of DUT above PG7000 reference level. Value is
negative if below reference level.
ATM head: Calculates and applies a fluid head correction to internal or external
barometer readings to correct the atmospheric pressure value to the PG7000’s
reference level if the barometer is reading at a different level (see Section 3.11.3.3).
The ATM head is calculated following:
B as H
gh ρ P
atm
=
Where:
atm
H
P
, ATM head [Pa] = fluid head correction applied to the internal or external
barometer reading.
ρ
as
, air density [kg/m
3
] = standard air density of 1.2 kg/m
3
.
g
, gravity [m/s
2
] = acceleration due to gravity (value as specified in the active
SETUP file, see Section 3.10).
h
B
, barometer height [m] = Height of the internal or external barometer above the
PG7000 reference level. Value is negative if below
reference level.