VIBRAROD™

BULLETIN 533

The VibraRod™ vibrating rod sensor provides reliable point level sensing in a wide variety of applications within powder and bulk solids markets. The vibrating probe principle utilized by the VibraRod overcomes typical application difficulties associated with changes in material, electrical dielectric constant, temperature or humidity while providing reliable solid state electronic circuitry that requires no calibration. The VibraRod has the ability to detect a wide range of material densities.

The VibraRod line of vibrating rod point level sensors is offered in standard length, cable extension or pipe extension versions. The standard length version extends into your vessel approximately 9 inches (235 mm). The pipe extended version can be used to extend the measuring rod up to 120 inches (3 m) and the cable extended unit can be used to extend the probe up to about 65 feet (20 m). Each version can be provided with either a plastic or aluminum housing. VibraRod units are provided with local indication using a bi-color LED and a traditional relay output.

Principle of Operation

The VibraRod™ line of point level sensors is a mechanical resonance system that is excited and kept in resonance by the sensor's electronic circuitry. Two piezoelectric crystals are mounted on the internal portion of the probe’s base. An electrical signal is applied to one crystal at the frequency corresponding to the probe’s self-resonance. This electrical excitation causes physical deformation of the crystal which in-turn creates probe vibration. When no material is present around the VibraRod's probe, the vibration of the probe is received by the second crystal. This causes physical deformation of the second crystal which generates a voltage analyzed by the electronic circuitry. With material present and surrounding the probe, the vibration is dampened so that the second crystal is not able to generate as high a voltage as when no material is present. The electronic circuitry senses this change and the relay output changes accordingly.

Applications

The VibraRod™ level sensor provides reliable point level sensing in a wide variety of applications for most bulk solid materials. The single-prong vibrating rod principle requires no calibration, is easily setup and eliminates the application problems associated with build-up and clogging between tines on a typical "tuning fork" device. The VibraRod is ideal for bulk solids ranging from 3.12 lbs/ft³ (0.05 kg/dm³ ) with a maximum particle size of about 3/8 inches (10 mm) and is even self-cleaning via vibration in many applications.

Features

SINGLE-PRONG PROBE DESIGN
The VibraRod™ provides a probe design superior to "tuning fork" devices and eliminates problems associated with build-up between tines of "tuning fork" devices. In addition, the VibraRod's vibration acts as a self-cleaning effect for most materials, which can further eliminate problems. The reinforced 316 stainless steel rod provides a high level of corrosion resistance suitable for virtually any application.

IMMUNE TO CHANGES
The unique design of the VibraRod level sensor makes it immune to changes in many different application variables including:

	Vessel contents
	Material composition
	Density of material
	Dielectric constant
	Particle size
	Moisture content
	Pressure and Humidity
	Temperature

NO CALIBRATION REQUIRED
The VibraRod level sensor is very easy to use. Unlike RF Capacitance type sensors, no calibration is required. Simple switch adjustments for time delay, fail-safe and sensitivity are all that is required to setup and use the VibraRod point level sensor.

SELECTABLE FAIL-SAFE MODE
The VibraRod is selectable for high or low fail-safe mode. This allows the user to set the output "state" upon alarm activation and power failure.

LOCAL INDICATION
Each VibraRod level sensor includes a bi-color LED to indicate power and material absence/presence (Ordinary location sensors only).

UNIVERSAL POWER SUPPLY
All VibraRod level sensors can be provided in either a high or low voltage design. The high voltage design can be used with 85-265VAC and 120-375VDC. The low voltage design requires either 16-40VAC or 19-55VDC. This added flexibility allows two power supply ranges to cover all possible requirements.

CHOICE OF HOUSING MATERIALS
A choice of either plastic or aluminum is offered.

CHOICE OF PROBE CONFIGURATIONS
Flexibility for virtually any bulk solids point level application (top or side mounted) is enhanced with a choice of three probe configurations: Standard, Cable Extension and Pipe Extension.

HAZARDOUS LOCATION VERSION
The Standard, Pipe Extended and Cable Extended configurations of the VibraRod level sensor (aluminum housing only) can be provided with ATEX hazardous area certification. This allows the VibraRod to be used in areas where hazardous explosive dust is present.

Available Configurations

STANDARD PROBE
The standard probe is approximately 9-1/4 inches (235 mm) in length and is suitable for both top and side mount applications. It mounts to the vessel with a 1-1/2" NPT or BSP connection.

PIPE EXTENSION PROBE
For high and low level applications that extend beyond the length of the standard probe, the VibraRod™ can be provided with a pipe extension probe. This configuration is intended for top mount applications only. The extension is constructed of 1" stainless steel pipe, which provides structural strength and affords a means to secure the assembly to the vessel. The pipe extension probe is available in lengths up to 10 feet (3 m) in length. The unit mounts to the vessel with a 1-1/2" NPT or BSP connection.

CABLE EXTENSION PROBE
The cable extension probe configuration extends the detection length beyond the standard and pipe extension probes. This version of the VibraRod level sensor is for use in top mount applications only and can be used for both high and low level applications. A polyethylene (PE) coated steel reinforced cable is used for the extension and is available in lengths up to 65 feet (20 m). The unit mounts to the vessel with a 1-1/2" NPT or BSP connection.

Specifications

* Influenced by the ambient temperature. Refer to Installation & Operation manual for details.

Warranty

Monitor Technologies LLC warrants each VibraRod™ it manufactures to be free from defects in material and workmanship under normal use and service for two (2) years from the date of purchase. The purchaser must notify Monitor of any defects 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 does not apply to any product which is repaired or altered outside of Monitor Technologies' 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.

533A.2.0406

Global Flour Processor Uses Flexar® Guided Wave Radar

A large global flour processor and food products company recently began using the Flexar® guided wave radar in a total of eighteen (18) silos and bins to manage their finished product inventory.  Readings from these continuous level sensors is reported as being reliable and accurate, even during pneumatic filling, contrary to their previous measuring system.  A previous non-performing ultrasonic system was replaced by the Flexar level sensors.  Flexar guided wave radar level sensors were chosen as the best for pneumatically filled dust laden flour silos.

Eight (8) Flexar level sensors are installed in load-out silos that fill bulk trucks with processed and finished flour.  These silos are 12ft in diameter and 35ft tall.  The finished flour is pneumatically conveyed into these silos.  During filling the internal environment of the silos is very dusty and turbulent.  The finished flour in these silos is used for loading bulk transport trucks for distribution.  In addition, ten (10) Flexar level sensors are installed in 40ft high bins that contain bran.  This material is also sent by bulk transport to end users.

All of the Flexar level sensors are equipped with an RS485 digital communications output that is connected to a PC with a graphical user interface for inventory management purposes.  Monitor’s SiloTrack™ inventory management software is used by the facility to monitor and manage material inventories of both the finished flour and the bran.  SiloTrack allows for multiple user viewing and data access via LAN and this is how the facility will be using the software that provides a flexible, graphical user interface, alarms, report generation and history analysis functions.

Guided wave radar is especially well suited to level measurement applications of dusty powder materials even when measuring during pneumatic filling.  Flexar guided wave radar utilizes TDR (time domain reflectometry) technology.  Radar pulses are continuously transmitted down the sensor’s probe and guided to the material surface where they are reflected back to the electronics along the wave guide.  The time-of-flight of the pulses is measured and directly related to the distance to the material surface and its level.

>>Click here for more information about Flexar guided wave radar continuous level measurement sensors.
>>Download Product Bulletin 353A
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