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SSI TECHNOLOGIES, INC.
Controls Division
2643 West Court Street
Janesville, WI 53548-5011
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
2
Copyright January 30, 2009
SSI Technologies Inc.
All Rights Reserved
Revision 4
RoHS
SSI Technologies – Application Note PS-AN4
MediaGauge™ (Model MG-9V) Digital Pressure Gauge
Product Overview
Chemical Compatibilities: Any gas or liquid
compatible with 304L and 316L stainless steel. For
example, Motor Oil, Diesel, Hydraulic fluid, Brake Fluid,
Water, Waste Water, Hydrogen, Nitrogen, and Air.
LCD Display Battery Saver Mode: MG-9V
automatically powers down after 5 minutes.
Multiple Pressure Units: PSI, BAR, MPA (kg/cm²)
(Optional Ft. of Head available)
Compact, Robust Package: 3 inches with black ABS
Thermoplastic case
Measurement Technology
In general, pressure measurement technology translates a
force from an induced pressure into an electrical quantity. In
digital pressure gauges, the electrical quantity is then
translated into pressure units and digitally displayed.
The SSI’s MediaGauge™ MG-9V digital pressure gauge
includes an 304L stainless steel input pressure port, a
piezoresistive pressure sensing element, signal conditioning
circuitry for temperature and calibration compensation, and
a LCD that displays the pressure measured in either PSI,
BAR or MPA (kg/cm²) units.
The piezoresistive sensing element consists of an oil-filled
micro-machined 316L stainless steel convoluted diaphragm
and a silicon crystal sensor. The silicon crystal sensor is
mounted on a 304L stainless steel housing and laser
welded to the diaphragm. Optimal media isolation is
achieved when the media’s pressure acts directly on the
316L stainless steel diaphragm and is then transferred
through the oil to the silicon sensor.
Strain gauges (resistive elements) in the silicon sensor are
used in a Wheatstone Bridge circuit. When the media’s
pressure is applied, the resistivity of the strain gauges
changes proportional to the pressure applied. One leg of
the bridge measures the input pressures port. The other
leg of the bridge is connected to the reference port (vacuum
pressure 0 PSI) the input pressure port is compared to.
Since piezoresistive pressure sensors are generally
sensitive to changes in temperature, the MediaGauge™
MG-9V digital pressure gauge uses signal conditioning to
compensate for temperature and calibration. The output
signal is then converted into one of 3 user selectable forms
(select units with the ON/UNIT/OFF button):
1) PSI
2) BAR
3) MPA (kg/cm²)
The MediaGauge™ MG-9V digital pressure gauge will
display the pressure reading after the ON/UNIT/OFF button
is depressed. The pressure measurement reading is
updated 3 times per second.