Fluke PG9000 Series, Руководство по эксплуатации и обслуживанию

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7. APPENDIX
Page 187 © 2011 Fluke Calibration
PISTON head: Calculates and applies a fluid head correction to compensate for
the difference between the current piston position and the PG9000’s reference
level (see Section 3.12.3.4).
The Piston head is calculated following:
( )
( )
rlo P a f H
h h g P
P
+ − =
ρ ρ
Where:
P
H
P
, Piston head [Pa] = fluid head correction applied to calculate defined
pressure.
ρ
f
, fluid density [kg/m
3
] = Density of test fluid at current pressure.
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 3.11). Assumed to be
zero when operating in absolute with a vacuum
reference mode. When using PG Differential
mode, calculated using static pressure density
measured by the Diff. Mode reference pressure
monitor.
g
, gravity [m/s
2
] = acceleration due to gravity (value as specified in
the active SETUP file, see Section 3.11).
h
P
, piston height [m] = Height of the current piston position above
PG9000 reference level (0.0 mm).
h
rlo
,
reference level offset [m] = Reference level offset of the piston (see Section
3.10.7).
7.2.2.2 Overall Fluid Head Correction
The overall fluid head correction for each PG9000 mode results from combining
the three head components. In general, overall head correction is given by:
P atm DUT
H H H H
P P P P
+ − − =
Gauge mode :
( ) ( )
( )
rlo P a f D a f HG
h h g gh P
+ − + − − =
ρ ρ ρ ρ
Absolute mode by adding atmospheric pressure: Air density is zero for all
components except for the ATM head which is used to compensate for
barometer height.
( )
rlo P f B as D f HA
h h g gh gh P
+ + − − =
ρ ρ ρ
Absolute mode with vacuum reference: Air density is zero for all terms and no
barometer is used.
( )
rlo P f D f HA
h h g gh P
+ + − =
ρ ρ
Differential mode: Head correction is the same as for absolute mode with
vacuum reference. Head correction for the height of the RPM is unnecessary
through the use of the RPM offset.
( )
rlo P f D f HA
h h g gh P
+ + − =
ρ ρ