SSI Technologies – Application Note PS-AN7
MediaGauge™ (Model MG-MD) Digital Pressure Gauge
Product Overview
Product Description
The MediaGauge™ MG-MD is a multi-functional digital
pressure gauge consisting of a media isolated
piezoresistive pressure sensing element, signal conditioning
circuitry for temperature and calibration compensation, a
304L stainless steel pressure port and a LCD back lit
display.
The MG-MD digital pressure gauge has an
accuracy of ± 0.25 % full scale
for 75 to 3000 psi.
The MediaGauge™ MG-MD digital pressure gauge is
powered by an external 8 – 30 Vdc external power supply
and comes standard with a wide variety of functions –
multiple pressure unit display readings (PSI, BAR or MPA
units); memory storage of maximum peak pressure reading;
zero adjustment; a 4-20 mA current output along with a limit
switch (NPN transistor) to interface to monitoring and
control systems.
The MediaGauge™ MG-MD is made of all laser-welded
304L & 316L stainless steel for optimal media isolation and
usage in a wide variety of media. These compact 3 inch,
robust digital pressure gauges measure pressures from
5 PSI to 5000 PSI and are ideal for a variety of industrial
and commercial applications such as process control,
refrigeration, compressors, pumps, hydraulics, pneumatics
and waste water.
The MediaGauge™ MG-MD digital pressure gauge has
better accuracy, longer life and standard multiple functions
which make it a better choice than mechanical pressure
gauges.
•
•
MediaGauge™
Model MG-MD with 2 meter cable.
Product Features
•
•
•
•
Superb Accuracy:
± 0.25% Full Scale
Pressure Ranges:
5, 15, 50, 75, 100, 200, 300, 500,
750, 1000, 1500, 2000, 3000, 5000 PSI
Keypad Operated Functions:
Auto zero; peak
hold and high and low pressure set points
Monitoring and control outputs:
4-20 mA output
and a limit switch (NPN transistor output) controlled
by the high and low keypad programmable
pressure set points.
Operating Temperature:
-10°C to 60°C
Storage Temperature:
-20°C to 85°C
SSI TECHNOLOGIES, INC.
Controls Division
1309 Plainfield Ave.
Janesville, WI 53545-0450
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
Copyright October 17, 2012
SSI Technologies Inc.
All Rights Reserved
Revision 4
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SSI Technologies – Application Note PS-AN7
MediaGauge™ (Model MG-MD) Digital Pressure Gauge
Product Overview
•
Typical Applications:
General Purpose, Test, Process
Control; MRO, Water, Compressors, Refrigeration; Fuel
Cells; Pumps; Hydraulics; Spraying Systems;
Pneumatics; Flow; Robotics; Agriculture; Hydrogen
Storage
•
NEMA 4X Rating
•
NIST traceable certificates available
•
Chemical Compatibilities:
Any gas or liquid
compatible with 304L Stainless Steel. For example,
Motor Oil, Diesel, Hydraulic fluid, brake fluid, water,
waste water, Hydrogen, Nitrogen, and Air.
•
Multiple Pressure Units:
PSI, BAR, MPA
(kg/cm²)
•
Compact, Robust Package:
3 inches with black ABS
Thermoplastic case
The piezoresistive sensing element contains an oil-filled
micro-machined 316L stainless steel convoluted diaphragm
and a silicon crystal semiconductor. 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 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 sensitive to
changes in temperature, the MediaGauge™ MD-MG digital
pressure gauge uses signal conditioning to compensate for
temperature and calibration prior to outputting the LCD
signal. The output signal is then converted into one of 3
user selectable forms (select units with the UNIT/SET
button):
1) PSI
The SSI’s MediaGauge™ MG-MD digital pressure gauge
consists of a 304L stainless steel input pressure port; a
piezoresistive pressure sensing element; signal conditioning
circuitry for temperature and calibration compensation; a
LCD that displays the pressure measured in either PSI,
BAR or MPA (kg/cm²) units; a 4-20 mA output signal and a
limit switch (NPN transistor output).
2) BAR
3) MPA (kg/cm²)
The MediaGauge™ MG-MD digital pressure gauge will
display the pressure reading after the UNIT/SET button is
depressed. The pressure measurement reading is updated
3 times per second.
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.
SSI TECHNOLOGIES, INC.
Controls Division
1309 Plainfield Ave.
Janesville, WI 53545-0450
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
Copyright October 17, 2012
SSI Technologies Inc.
All Rights Reserved
Revision 4
2
RoHS
SSI Technologies – Application Note PS-AN7
MediaGauge™ (Model MG-MD) Digital Pressure Gauge
Product Overview
Example Using High & Low Set Points
The MediaGauge™ MG-MD also has two keypad
programmable pressure set points – a low limit set point
and high limit set point. These set points control the limit
switch (NPN transistor output).
To understand the high and low pressure set points
functioning, let’s look at a typical application where the
MediaGauge™ MG-MD in used in a monitor and control
system.
VCC
1
2
3
4
Supply Source
COM
Limit Switch Operation
VCC
(White)
4 - 20 mA OUT
(Blue)
Switch Output
(Brown)
In the graph shown here, you can see how the user can
program the high and low set points to control when the
relay would turn on and off.
Input pressure values below the low limit set point or higher
than the high limit set point will result in a limit switch output
(Brown Wire) of 0 Vdc.
Input pressure values within the control set point limits
(between the low and high set point values) will result in a
limit switch output that follows the external power source.
Note: The 4-20 mA output (Blue Wire) is proportional to the
input pressure and operates independent of these low and
high set points.
Meter
Ground
(Black)
RELAY
NO
NC
MediaGauge ™
4 Pin Mini DIN
In the example shown above, the MediaGauge MG-MD is
attached to an external power supply, a current meter and a
relay. We will assume the low set point has been set to 100
psi and the high set point has been set to 375 psi.
SSI TECHNOLOGIES, INC.
Controls Division
1309 Plainfield Ave.
Janesville, WI 53545-0450
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
Copyright October 17, 2012
SSI Technologies Inc.
All Rights Reserved
Revision 4
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RoHS
SSI Technologies – Application Note PS-AN7
MediaGauge™ (Model MG-MD) Digital Pressure Gauge
Product Overview
MediaGauge™ MG-MD Panel
MediaGauge™ MG-MD panel has a LCD display and three
;
UNIT/SET;
multi-functional buttons:
To display the pressure reading in a different pressure unit:
Press the
UNIT/SET button
until the arrow in the LCD points
to the pressure units desired.
To check the value of the low pressure setting:
Press and
release the
button,
the low pressure set point will be
displayed for 30 seconds.
To check the value of the high pressure setting:
Press and
button,
the high pressure set point will be
release the
displayed for 30 seconds.
To see the maximum peak pressure the unit has measured:
Press and hold down the
button
for 3 seconds. The
maximum peak pressure value will be displayed and will
blink on the screen.
To reset the maximum peak pressure:
Press and hold down
the
button
for 3 seconds, and the peak hold value will
reset.
To return to the current pressure reading:
Press and hold the
X
button
for 3 seconds and the gauge will be back to the
measurement mode, the current pressure measurement will
be displayed and will not blink.
To power on the unit:
There is no ON/OFF button on the
MediaGauge™ MG-MD model.
The MG-MD unit is
powered on and off via the external 12V supply voltage
source.
When the external supply voltage is between 8 - 30 Vdc, the
LCD will be backlit and will continuously display the
pressure measurements.
To reference your MediaGauge™ digital pressure gauge to the
input port:
Press and hold down the
button
and the
button
at the same time for 3 seconds. For example, if
you have 20 psi on the display and then you press and hold
button
simultaneously for 3
down the
button
and the
seconds, the display will show 0.0 psi. A measurement of
30 psi would then read as 10 psi on the display.
To reset the MediaGauge™ digital pressure gauge:
Make sure
the input port is either disconnected or connected to a 0 psi
input.
Press and hold down the
button
and the
S
button
at the same time for 3 seconds.
SSI TECHNOLOGIES, INC.
Controls Division
1309 Plainfield Ave.
Janesville, WI 53545-0450
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
Copyright October 17, 2012
SSI Technologies Inc.
All Rights Reserved
Revision 4
4
RoHS
SSI Technologies – Application Note PS-AN7
MediaGauge™ (Model MG-MD) Digital Pressure Gauge
Product Overview
To set the High or Low pressure set points:
Press and hold
down the
UNIT/SET button
for 3 seconds. The
MediaGauge™ MG-MD will go into the pressure setting
mode.
1)
The screen shows on the top, left hand side
indicating high pressure setting, and the first digit
will be flashing.
2) Set the first digit value by pressing the
Button
(select from 0 to 9). Then press the
Button,
which shifts to the second digit. Again use the
Button
to select 0 thru 9 followed by the
Button
to complete the third and forth digits.
3) After all 4 digits of the high pressure settings are
done press the
Button
one more time, the
on the top, left hand side
screen will show
indicating low pressure setting. Repeat steps 1 and
2 above to set the 4 digits of the low pressure
settings.
4) After all 4 digits of the low pressure settings are
done press the
Button
one more time, the
screen will show “Load”, indicating your pressure
settings have been saved into memory.
5) To make sure that the settings are correct, you can
press the
Button
to check the value of the low
Button
to check
pressure setting and press the
the value of the high pressure setting.
Electrical Interface
MediaGauge™ MG-MD harness connections:
White wire:
Black wire:
Brown wire:
Blue Wire:
Power Lead for supply input (12 Vdc)
Return Lead
Limit Switch output (NPN Transistor output)
4-20 mA output for meter. (Must be loop
grounded with black wire)
Typical Wiring Interface
This is a description of an application to interface the
MediaGauge™ MG-MD to a monitoring and control system
utilizing the limit switch output to control a relay and monitor
the output current. The relay will turn on and off based
upon the high and low pressure set points the user
programs into the MediaGauge™ MG-MD digital pressure
gauge.
1)
Mount the MediaGauge™ MG-MD digital pressure
gauge on a suitable (1/4” NPT) female fitting. Use
Teflon tape or pipe dope to seal the threads. . Do
not over tighten. Torque to 150 in lbs +/- 1 in lb.
2) Connect the supplied mating harness with Din
connector to the mating connector on the back of
the MediaGauge™ MG-MD digital pressure gauge.
3)
Program the MediaGauge™ digital pressure gauge
with your low and high pressure set points per the
instructions described previously.
SSI TECHNOLOGIES, INC.
Controls Division
1309 Plainfield Ave.
Janesville, WI 53545-0450
Phone: (608)758-1500
Fax: (608)758-2491
www.ssitechnologies.com
Copyright October 17, 2012
SSI Technologies Inc.
All Rights Reserved
Revision 4
5
RoHS
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