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.

DOC-000-533A
Rev.3.12052008

Solids Flow Detection

Microwave solids flow detectors can be used in a variety of applications including feed mills & grain processing, consumer foods (cereal, sugar, cocoa, coffee), chemicals & pesticides and more. For example, one company uses Monitor’s Model SFD-2 solids flow detector to verify the flow of feed pellets through their various transport lines which involves a process where a horizontal screw auger is conveying pellets over to a vertical gravity chute.  The chute then directs the pellets to a process down below. They have carefully placed the SFD-2 so that it detects the pellets as they fall directly across the sensor face. (See Below)

The Model SFI and SFD-2 line of solids flow detectors from Monitor Technologies, LLC provide analog or relay outputs to indicate the flow / no-flow condition of powder and bulk solids materials in chutes and pneumatic conveying lines.  Using microwave Doppler radar technology these units are non-invasive plus extremely reliable and rugged to withstand the rigors of the installation and your process extremes. From automated systems with pneumatic lines to gravity chutes, solids flow monitors can help to improve process performance. They can assist in detecting flow problems, as well as, enhance the level of automation at a facility like turning a conveyor on or off.

For more information on Solids Flow Detectors click here or contact Monitor Technologies LLC at 800-766-6486 in the USA and 630-365-9403 worldwide.

>>Click here for more information about Solids Flow Detectors from Monitor Technologies.
>>Click here for more information on Plug Chute Solutions
>>Download Product Bulletin 813