from the sensor.
Unlike other sensing technologies,
these sensors are capable of detecting
all materials, liquid, granular and solid,
regardless of color, shape and composi-
tion, transparent or opaque, including
powder, food products, grains, chemi-
cals, pharmaceuticals, oils, plastics and
objects that change colors. The sensors
are available in either ULTEM® plastic or
SS303 stainless steel housings which
are fully encapsulated to withstand
shock and vibration. Both are sealed to
withstand dusty, dirty, clean-in-place,
noncondensing humidity, high-pressure
washdown environments, and they are
virtually unaffected by changing light
conditions, colors and noise. With
housings that meet NEMA 4X and IP67
industry standards, the sensors resist
most acids, bases and oils, including
most food products. All the sensors in
this model series are CE certified.
Additionally, the Model SM902 series
sensors offer dependable operation and
compatible integration with most
programmable logic controllers.
1-meter and 2-meter-
range models
In the Model Reference Guide, the
standard 1-meter-range models are
identified as the Model SM902A-1 and
SM952A-1 series sensors, and the 2-
meter-range models are identified as the
Model SM902A-4 and SM952A-4 series
sensors. Respectively, these models
provide for dual-level sensing from 50.8
mm to 1 m (2 to 39") and 120 mm to
2 m (4.7 to 79"). The length of the
connector model, excluding the connec-
tor/cable assembly, is just 96 mm (3.78"),
thus adding to the mounting conve-
nience. These sensors operate on a
sonic frequency of 200 kHz and are
available with response times as fast as
150 ms. The FDA approved silicone
rubber transducer face, while used to
couple the ultrasonic energy to the air,
is also resistant to most acids, bases,
oils and food products. Selected sensors
in this model series are DeviceNet
capable.
For dual-level-control sensing applica-
tions that involve severe, corrosive-type
environments, the Model SM902A-7STS
and SM952A-7STS sensors have an
SS303 stainless steel housing with an
SS304 stainless steel-faced transducer.
These models, with a sensing range of
120 mm to 1 m (4.7 to 39"), provide
reliable operation in the detection of
certain strong chemicals and corrosive
materials, and where caustic cleaning
solutions are used in washdowns of
machinery and equipment in close
proximity to the sensor. For out-of-doors,
dual-level-control sensing applications,
where cold weather is a factor, these
corrosion-resistant models provide
reliable operation in temperatures as
low as -10° C (14° F).
Nonlevel-control applications ideally
suited for these sensors within the 1-
and 2-meter ranges include: container
accumulation detection on mass
conveyors and controlling either loop
positions or tension on web processing
lines relative to two set control limits.
8-meter,
long-range models
No other discrete, level-control sensor
on the market has as short a deadband,
as long a sensing range, and is housed
in as small a package as the Model
SM902A-8 and Model SM952A-8 series
of long-range, ultrasonic, dual-level
sensors. As indicated in the Model
Reference Guide, these 30 mm sensors
detect objects over a sensing range of
just 203 mm (8") to 8 m (26'). The
116.31 mm (4.579") length of the cable
model, a fraction of the size of other
long-range sensors, ensures easy
installation. The sensors operate on a
sonic frequency of 75 kHz with a
standard response time of 1 second with
other response times available. The
transducer face of the fully encapsulated
sensor is made of epoxy which, in
addition to coupling the ultrasonic
energy to the air, allows the sensor to
perform in a wide range of harsh
environments including those involving
most acids, bases and oils.
Applications for these long-range,
dual-level sensors can be found in
almost every industry or business when
reliable detection within the range of 8
meters (26 feet) is required. By virtue of
the 75 kHz sonic frequency, the sensor’s
wide, 20-degree beam is especially
effective in sensing the levels of various
types of liquids, solids and granules as
close as 203 mm (8") from the sensor’s
face. These applications include the
processing of food and beverage
products and pharmaceuticals, as well
as the treatment of water and sewage.
In the sensing of dry materials, such as
grains and powders, the long-range,
dual-level sensors offer an efficient
alternative to certain limit switch devices
which can be prone to frequent mainte-
nance problems and unreliable
operation.
In applications where high sound
absorption conditions may exist in the
material being detected, and either the
one- or two-meter range model sensor
becomes unreliable because of lost
energy, the more powerful long-range
SM902 can provide the solution when
used within the sensing ranges of either
one or two meters.
Temperature compensation allows
these long-range sensors to operate
reliably in outdoor applications in
temperatures ranging from
-20° to 60° C
(-4° to 140° F).
Operation
The SUPERPROX® Model SM902
series sensor, operating on 12 to 24 VDC
regulated power, is a self-contained,
pulse-echo, dual-level, sensing device
that monitors and controls most nonhaz-
ardous material levels within the speci-
fied sensing ranges. With extremely
short deadbands, the sensors are
capable of detecting levels of liquids,
solids and powders as high as 51 mm
(2") from the sensor face.
Before operation, a pushbutton
“teach” function is used to set the
sensing window limits. The near and
far limits of a desired sensing window
can be set anywhere within the sensing
range and may be set to encompass
the full sensing range or be as small as
desired. A double press of the SETUP
pushbutton, makes possible the setting
of a default window anywhere within the
sensing range.
Functionality in the operation of the
30 mm, long-range sensors includes the
capability to be configured for various
NPN and PNP, Normally Open, Normally
Closed or Complementary output modes
for: pump-in latch or pump-out, with and
without alarm or setpoint, and dual
alarm/dual setpoint operations. A loss-
of-echo feature can be selected to hold
the output in the event of a loss-of-echo
condition.
During setup and operation, a
multicolor LED indicates the limits setup
and operational modes; a red LED
illuminates when the output is in an
active (On) state.
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