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Vibratory Level Sensor -
Diamond Shaped Probe

PZP Vibratory Level Indicator

Bulletin Button

Unique versatility for materials from 1.25 to 100 lb/ft³ (20- 1600 kg/m³ )

Ideal for lightweight materials including expanded polystyrene beads and fumed silica.

Unaffected by environmental and material changes

Unique single-prong probe design (diamond shaped)

Universal Power Supply for 20–250 VAC/DC

High and low applications/dust collector back-up protection

Handle Internal Bin Temperatures Up to 302°F (105°C)

Multiple configurations for a wide range of applications



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.


.: Principle of Operation

.: Applications

.: Features

.: Available Configurations

.: Specifications

.: Warranty


Principle of Operation

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.


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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:






Carbon Black



Food Products






Fly Ash



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




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.


Available Configurations

Dimensions 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.


Standard Vibratory Level 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.


Pipe Extension Level 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.


Extension Level Probe


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).


High Temp Level Sensor



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.


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


Jumper selectable (high - FH, low - FL)

Operating Frequency:

280 Hz


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


Red LED – Status dependent on material sensing and il-safe selection

Solid Extension:

1" pipe, 304ss, 12' (3.6m) length max. (customer specified length)

Cable Extension:

Polyurethane sheathed, steel rope reinforced; 20' (6.1m)length max. (customer specified length)

Interconnection Distance:

6' (1.8m) factory installed flexible conduit (hi-temp models)


4.5 LB (2 kg)(standard model only)



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.


Part Numbers / Product Configurations
Monitor Logo

Part # > Product Configuration
9-8300 > PZP,STD,20-250VAC/DC
9-8302-10 > PZP,CBL EXT,20-250VAC/DC,<10'
9-8302-20 > PZP,CBL EXT,20-250VAC/DC,>10'
9-8304 > PZP,PIPE EXT,20-250VAC/DC
9-8306 > PZP,HT,STD,20-250VAC/DC
9-8308 > PZP,HT,PIPE EXT,20-250VAC/DC



Last Rev.: June, 2014



Mass Flow Measurement Systems
The QuantiMass in-line mass flow sensor measures the flow of quantities in pneumatic conveying & free-falling processes. The sensor is based on the latest Microwave Doppler Effect technology and provides fast, in-line / on-line measuring without the use of weight scales.
The sturdy, non-intrusive design of the sensor minimizes maintenance. In addition, the compact size of the sensor makes for easy installation into existing processes. Suitable for powders, dust, pellets, and granular up to 0.75 inch (2cm).

Ultra Series-Includes controller
PRO Series-Includes transmitter

A practical application for the QuantiMass would be to monitor material flow rates to verify blending mixture ratios.

Principle of Operation:
The QuantiMass Mass Flow Measurement Sensor / Meter is designed with the latest microwave technology and is used to continuously quantify the flow of powders & solids being conveyed in metallic pipes. The QuantiMass is based on technology that has been developed and proven by Muetec Intruments over several years. The measurement process of the sensor is centered on the Doppler effect. The mass flow-rate is determined by evaluating the frequency and amplitude changes during the measurement process. Particles at rest, such as deposits, do not influence the measurement. All powders, dust, pellets and granules can be measured reproducibly, up to the size of 0.75 inch (2cm). The QuantiMass sensor is suitable for continuous in-line / on-line measurements in pneumatic conveying or in free-fall pipelines.

Click here for more information on the QuantiMass
or contact Monitor Technologies LLC at
Tel.: 800-601-6319 in the USA and
Tel.: 630-365-9403 worldwide.
>>Download QuantiMass Ultra Bulletin

>>Download QuantiMass PRO Bulletin

>>Download QuantiMass Application Questionnaire (Excel file)

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