Description; General Information - Fluke RUSKA 2465A-754 User Manual

Chapter 3

Description

General Information

The RUSKA 2465A-754 Gas Piston Gauge (see Figure 3-1 and 3-2), is a pneumatic
pressure standard designed for the accurate generation and measurement of gas pressures
to 1000 psi. This measurement is accomplished in the basic manner of using the
=
PRESSURE FORCE / AREA
fundamental pressure equation (see Chapter 2 for more
information). The gauge is used as the precision measuring device in the RUSKA Gas
Lubricated Piston Pressure Gauge System.
It may be seen from the above general equation that when a known force produced by a
known mass is applied to a piston of a known area, a pressure will be produced that may
be calculated (see Appendix A for detailed information). The RUSKA gauge is arranged
for the application of carefully determined masses on a piston of known area.
The primary feature of the gauge is its ability to accurately reproduce its performance at
the lower pressure. The low viscosity of the gas provides excellent lubrication for the
close-fitting piston/cylinder assembly. Relative motion between the piston and cylinder is
necessary and is obtained by an electric motor which is used to distribute the gas
molecules throughout the annulus of the assembly. It is relative absence of friction
between piston and cylinder walls that characterizes the performance for which the gauge
is so highly respected.
A second feature of the gauge is its ability to measure either absolute pressures or those
referenced to the atmosphere. The gauge is equipped with a bell jar which, when placed
over the weights, permits reduction of the external reference air pressure to a value of
100 microns Hg (mercury) at 0 ºC.
The nominal range of pressure (interval) over which the gauge is capable of operating is
the span from 1.4 kPa (0.2 psi) to 4.8 mPa (1000 psi). This interval is covered by three
interchangeable piston/cylinder assemblies having sufficient overlap for establishing
continuity of measurement and for making detailed investigations of subintervals within
the total range (span).
Some of the most important industrial uses of the gas lubricated piston pressure gauge is
that of a standard for calibrating transducers, Bourdon-tube type gauges, manometers,
and other dead weight gauges.
3-1