13. GLOSSARY
Page 153
© 2007 DH Instruments, a Fluke Company
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Absolute
As in
absolute pressure
. Pressure expressed relative to vacuum.
Absolute Differential
Differential pressure determined at near vacuum line pressure. The pressure expressed by the
FPG when a vacuum reference device is not used in absolute mode.
Adder
A value added to internal sensor readings to offset the readings (pressure adder, temperature adder,
humidity adder, vacuum adder) for calibration adjustment.
Ae
Piston-cylinder effective area.
Crossfloat
Process of comparison of two piston-cylinders in which they are connected together under
pressure and the mass of one is adjusted so that both pistons float together at a common
pressure. Used to set the line pressure in high line differential measurement mode.
Differential
As in
differential pressure
. Pressure expressed relative to a static pressure.
DUT (Device Under Test)
The device being tested or calibrated.
DUT Head
Fluid head correction to the pressure defined by the FPG8601 to predict the pressure at the level
of the DUT which may be different from the FPG8601 reference level.
FS (&DUTFS)
The full scale value is the maximum value or the span of a measurement range. Limits and
specifications are often expressed as % FS.
g, gl
Acceleration due to gravity (g). Acceleration due to gravity at location of use (gl).
Gauge
As in
gauge pressure
. Pressure expressed relative to atmospheric pressure.
Head
Fluid head, a pressure difference due to a difference in height. See also ATM head, DUT head
and PISTON head.
HSTOP, LSTOP
High stop and low stop, piston maximum end of stroke positions.
InHg
Pressure unit of measure, inches of mercury.
InWa
Pressure unit of measure, inches of water.
kcm
2
Pressure unit of measure, kilogram per centimeter square.
Line Pressure
Pressure relative to which the differential pressure is defined.
Measurement Mode
Mode in which FPG is defining pressures. These include gauge (pressure relative to atmospheric pressure),
absolute by vacuum (pressure relative to absolute vacuum determined by establishing a vacuum
in the reference port of the FPG), and absolute differential (pressure relative to atmospheric or
another static pressure determined by subtracting the static pressure from absolute by vacuum).
Mass Bell
The sleeve loaded onto the piston to carry other masses.
Multiplier
A value by which internal sensor readings are multiplied to change their slope (pressure multiplier,
temperature multiplier, humidity multiplier, vacuum multiplier) for calibration adjustment.
N2
Nitrogen gas.
Normal
A conventional or standard value.
PC
Piston-cylinder, piston-cylinder module.
PISTON Head
Fluid head correction based on the difference between the piston’s current position and the
reference level.
PRT
Platinum Resistance Thermometer. The element used in the piston-cylinder mounting post to
measure temperature.
Ready/Not Ready
Indication of when conditions are present to make in tolerance pressure definitions based on
specific criteria for each condition.
Reference Level
Height at which pressures are defined. The FPG8601 defines pressures at its reference level.
Fluid head corrections correct the pressure relative to the reference level.
RPT
Reference pressure transducer.
Tare (Zero)
The process of setting the current forces on the FPG to zero.
True Mass
The actual mass of an object without the buoyancy effect of atmosphere.
User Level
Level of security that can be set to protect certain FPG functions from being accessed.
