PZP vibratory level sensor provides reliable point level
detection in a wide variety of process control applications
within the powder and bulk solids market.
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.
ability to detect a wide variety of material densities, including
very lightweight materials, makes it an attractive solution
for many applications.
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
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.
Monitor's experienced application engineering staff to help
determine if the PZP is right for your particular application.
Applications include, but are not limited to:
The unique design makes the PZP immune to changes in many
different variables including:
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.
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.
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.
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.
are shown in inches with millimeter equivalent in brackets
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.
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.
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.
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).
20-250 VAC 50/60 Hz 20-250 VDC
Internal Bin Temp:
to +140° F (-30° C to 60° C)
to 176° F (+80° C)
to 302° F (+150° C)
dry contact; 5 amps @ 250 VAC max.
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)
fixed delay of 1 second
Hold-on, fixed delay of 2-5 seconds
selectable (high - FH, low - FL)
cast aluminum, beige powder coat; NEMA 4; IP65
PSI (10.4 bar)
x 1.5 cable gland, remove for 1/2" NPT
Red LED – Status dependent
on material sensing and il-safe selection
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.
The TrueCap® Model MK-2 RF Capacitance
point level probe is designed to provide a superior and stable sensitivity
threshold making it suitable for a variety of powder / bulk solids
and some liquid or slurry applications.
Advanced features of the
Model MK-2 include: > Automatic immunity to material build-up on the
probe by its driven shield design > Push-button calibration > Enhanced temperature
Maximized reliability via smart sensing algorithms like “self-validating” fail-safe
protection > Visible status LED on ordinary location
units > Versatility through a variety of configuration
options including: hazardous location version, split architecture
design, quick-connect process connection, stub probe, cable extensions,
solid extensions, Nylon® probes, Ryton® - equiv. probes,
A practical application for the TrueCap would be to use this level sensor where
a residual material build-up on a different sensor would cause a false
material level indication.
Principle of Operation for the TrueCap RF Capacitance Level Probe:
wall and the active probe element establish an impedance reference between each
other when exposed to air which has a dielectric constant of 1. When materials
with a dielectric constant greater than 1 are in close proximity to the probe,
the impedance of the sensing field between the sensor and the vessel
wall will change. Once the amount of change exceeds a threshold that
was electronically determined during the calibration process, an
output relay will either be energized or de-energized depending upon
the position of the fail-safe selector on the probe’s electronic
circuit board. A change of as little as .5 pico-farad is all that
is necessary for the probe to sense the presence of material.