The
PZP vibratory level sensor provides reliable point level
detection in a wide variety of process control applications
within the powder and bulk solids market.
The PZP
offers many advantages over alternative technologies. The
vibrating probe principle eliminates problems associated
with temperature, humidity and material changes, while providing
state-of-the-art electronic reliability and accuracy that
requires no calibration. The unique single-prong probe design
eliminates material packing problems and false signaling
typically associated with the dual-prong "tuning fork" design.
The PZP's
ability to detect a wide variety of material densities, including
very lightweight materials, makes it an attractive solution
for many applications.
The
PZP utilizes piezoelectric technology to create a vibration
and then constantly monitors the presence or absence of that
vibration. Two piezoelectric crystals are located in the
base of the probe. A signal is applied to one crystal at
the frequency corresponding to the probe's self-resonance.
The electrical excitation causes physical deformation of
the crystal resulting in probe vibration. With no material
present, the vibration of the probe is felt by the second
crystal. This vibration causes physical deformation of the
second crystal which generates a voltage to be analyzed by
the electronic circuitry. With material present around the
probe, the vibration is dampened, thereby minimizing the
voltage generated by the second crystal. The output voltage
is analyzed by the circuitry and the relay status changes
accordingly.
The
PZP is often applied in ultra lightweight applications due
to its exceptional sensitivity to materials as light as 1.25
LB/ft³ (20 kg/m³ ). However, the PZP is also a proven performer
for materials up 100 LB/ft³ (1600 kg/m³ ). Current applications
range from 1.25 LB/ft³ (20 kg/m³ ) EPP (expanded polypropylene)
beads to 100 LB/ft³ (1600kg/m³ ) clay. The PZP is ideal
for applications where vessel content changes are common,
since no calibration is required when material changes are
made. The PZP can also provide dust collector back-up protection.
Consult
Monitor's experienced application engineering staff to help
determine if the PZP is right for your particular application.
Typical
Applications include, but are not limited to:
Chemicals
Clay
Sawdust
Grain
Plastics
Carbon
Black
Polystyrene
Cement
Food
Products
Cereal
Rice
Flour
Lime
Tobacco
Fly
Ash
Features
VERSATILITY
The unique design makes the PZP immune to changes in many
different variables including:
Vessel
Contents
Material
Composition
Density
of Material
Dielectric
Constant
Particle
Size
Moisture
Content
Temperature
Pressure
Humidity
EASE OF USE
The PZP offers maximum ease of use to its users. PZP setup
involves simply selecting the sensitivity and fail-safe
settings, and requires no calibration.
SUPERIOR
PROBE DESIGN
The PZP offers a superior probe design over similar devices.
The unique single-prong probe design minimizes material packing
problems and false signaling that are typically associated
with the dual-prong "tuning fork" design. Also, the
vibration acts as a self-cleaning effect which can further
eliminate problems. The reinforced stainless steel probe construction
allows use with a wide range of materials.
FAIL-SAFE
A jumper permits selection of either high or low fail-safe. In the event of
a failure, the relay drops into the mode which denotes an alarm condition.
This alarm provides additional security against overfilling or emptying
of a vessel.
UNIVERSAL
POWER SUPPLY
The PZP's electronic module is a universal power supply configuration capable
of operating off 20 - 250 VAC 50/60 Hz and 20 - 250 VDC.
Available Configurations
Dimensions
are shown in inches with millimeter equivalent in brackets
STANDARD
PROBE
The standard probe is approximately 7" (178mm) in length and is suitable
for both top and side mount applications. It mounts to the vessel via
a 1-1/2" mounting gland.
PIPE
EXTENSION PROBE
For high and low level applications that extend beyond the length of
a standard probe, Monitor offers a pipe extension probe. This configuration
is intended for top mount applications only. The extension is constructed
of 1" NPT stainless steel pipe which provides structural strength and
affords a means to secure the assembly to the vessel. Available in lengths
up to 12' (3.6m), this unit is factory sized to the customer's specifications.
FLEXIBLE
CABLE EXTENSION PROBE
The cable extension configuration extends the detection length beyond
the standard probe length. This self-contained unit is for use in top
mount applications and can be used for both high and low level detection.
A polyurethane sheathed, steel rope reinforced cable is used for the
extension, and is available in lengths up to 20' (6.1m). The unit mounts
to the top of the vessel via a 1-1/2" mounting gland.
HIGH
TEMP/REMOTE ELECTRONICS
This configuration offers a split-architecture design that removes the
electronics to a remote mounting location away from the vessel. The furnished
cable allows for a 6' (1.8m)separation between the probe and the remote
electronics. This unit offers a reliable solution for applications that
involve high temperatures or in vibrating vessels that reduce the reliability
of most level sensors. The probe can be top or side mounted for use in
high or low level applications. For top mount applications, the probe
can be ordered with a pipe extension (see above).
Specifications
Power
Requirements:
Universal
20-250 VAC 50/60 Hz 20-250 VDC
Power
Consumption:
3
VA max.
Max
Internal Bin Temp:
-22° F
to +140° F (-30° C to 60° C)
Operating
Temperature:
Std
Models:
to 176° F (+80° C)
Hi-Temp
Unit:
to 302° F (+150° C)
Output
Relay:
SPDT
dry contact; 5 amps @ 250 VAC max.
Sensitivity:
1.25
lb/ft³ (20 kg/m³ ) minimum material density
Jumper selectable: A (High > 1.25 lb/ft³ )(20 kg/m³ )
B (Medium > 10 lb/ft³ )(160 kg/m³ )
C (Low, product build-up applications)
Time
Delay:
Hold-off,
fixed delay of 1 second
Hold-on, fixed delay of 2-5 seconds
Fail-Safe:
Jumper
selectable (high - FH, low - FL)
Operating
Frequency:
280
Hz
Enclosure:
Die
cast aluminum, beige powder coat; NEMA 4; IP65
Probe/Gland
Material:
304
stainless steel
Process
Connection:
1-1/2" NPT
Pressure
Rating:
150
PSI (10.4 bar)
Wire
Entry:
M20
x 1.5 cable gland, remove for 1/2" NPT
Indicators:
Red LED – Status dependent
on material sensing and il-safe selection
Monitor
Technologies LLC warrants each PZP vibratory point level
sensor it manufactures to be free from defects in material
and workmanship under normal use and service within two (2)
years from the date of purchase. The purchaser must give
notice of any defect to Monitor within the warranty period,
return the product intact and prepay transportation charges.
The obligation of Monitor Technologies LLC under this warranty
is limited to repair or replacement at its factory. This
warranty shall not apply to any product which is repaired
or altered outside of the Monitor Technologies LLC factory,
or which has been subject to misuse, negligence, accident,
incorrect wiring by others or improper installation. Monitor
Technologies LLC reserves the right to change the design
and/or specifications without prior notice.
523A.6.0407
Spotlight: True Fail Safe Level Switch
SafePoint®
"Truly" Fail-Safe Level Switch
The
SafePoint® rotary paddle level switch with a self-validating design
detects material presence plus continuously monitors its own ability
to function. The analysis includes sensor health and system power
failure, which makes the SafePoint truly fail-safe.
The SafePoint incorporates patented use of Hall-Effect technology,
dual outputs to indicate both material presence and unit health,
and microcontroller technology to continuously protect bulk solids
processing and storage from the consequences of unknown sensor
failure by providing immediate indication of a sensor failure
and confirmation of proper operation.
Other practical features of the SafePoint include rugged construction,
motor shut-off when paddle becomes impeded to maximize motor life, twist On/Off
cover for bolt free removal, and local status indicating light (except hazardous
location models)
A practical application for the SafePoint would be to use this "true"
fail-safe product if undetected sensor failure could result in a
catastrophic process problem.
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