Microwave Flow Sensor Working Principle

Microwave Flow Sensor is a Non-contact Flow Sensor which emits the microwaves of 2.4GHz from the tip of its sensor.

Reflected from the surface of powders and solids traveling in a pipeline, the microwaves get modulated in their frequency on the Doppler effect principle.

The sensor, detecting the frequency difference between transmitted and reflected microwaves, transforms it and amplifies to output contact signals.

It can reliably detect a little flow or motion of the powder or the grain in chutes or pneumatic conveying lines, which has so far been considered to be very difficult.

Microwave Flow Sensor

A microwave-based motion detector detects the Doppler shift of the flowing material.

A complete flow detector consists of a transmitter and transducer.

The transducer has a Gunn diode configured within a waveguide (horn) antenna and functions as both a microwave transmitter and receiver. The transmitter contains the measuring electronics and relay output.

The Gunn diode emits a low power, continuous signal that is reflected from moving material in the process.

It monitors the movement of bulk materials and can be used to detect and indicate material blockages or feeder shutdowns.

If the reflecting medium is moving, there will be, in accordance with the Doppler effect, a frequency shift between the transmitted and the received signals.

The frequency shift is proportional to the velocity of the process material. The transducer superimposes the transmitted and received signals.

Since the two frequencies differ only slightly, the differential signal produced is low frequency.

This low frequency signal is delivered to the electronics by capacitive coupling and processed in a low frequency amplifier.

Applications

Monitor’s Solids Flow Detector and Indicator can be used in a variety of applications to detect flow/no-flow conditions of powders and solid materials.

*Detection of a partial or full plug in a conveying line

*Detecting the bridging of material in a storage vessel upstream

*Sensing inadequate or a lack of flow due to upstream equipment failure (conveyor, blower, diverter valve, feeder)

*Verifying flow conditions Arrow Turning on/off equipment or processes downstream

Comments

What is a Torbar? – Averaging Pitot Tubes

The Torbar is employed for flow measurement of liquids, gases, or steam in circular, square, or rectangular section ducts for large flow rates. The Torbar is an insertion type multi-port self-averaging primary sensor for flow measurement. Torbar TORBAR is a set of Pitot tubes mounted on a bar across the pipeline with no moving parts. An averaging Pitot tube is a technology, while TORBAR is a manufacturing brand name. There are several brands available in the market with VERABAR, ANNUBAR, etc. Averaging Pitot Tube Principle Purpose Averaging Pitot tube can be employed when the average velocity of the flow profile, rather than the velocity in a specific point in the cross-section is desired. Averaging Pitot Tubes Principle It measures the differential pressure between the static pressure tap and the tap of full pressure of a stream. Thus such magnitude of differential pressure is directly proportional to the square of the flow rate. Working The TORBAR is designed in such a way that ...

Ferrules and Cross Ferruling

Ferrules are identification labels provided for every wire terminations in an instrument, equipment, or electrical/instrumentation control panels. These tube-shaped sleeves can be inserted easily on each individual wire in a multi-core cable. In earlier days fixed digits/letters are used as ferrules, but now Instrumentation engineers/technicians prints out desired ferrules by using a ferrule printing machine. Typical Ferrule The numbers/ letters on the ferrules will be given as per the approved electrical hook up or loop diagrams. This helps technicians to easily identify a particular loop/wiring from a series of terminal blocks and to troubleshoot the desired terminal connection. Separate numbers on the ferrules distinguish the positive and negative polarities of wires, thus ensure the polarity protection of the instrument. Cross Ferruling As a wire is connected on its both ends, it is quite useful to use a cross reference method for wire identification. Unlike normal ferru...

Thermowell Insertion and Immersion Length

The thermowell is the industrial housing for temperature elements like RTD or thermocouple or temperature gauges. Thermowell is directly exposed to process fluid/media. Inside the thermowell, element/gauge is installed. Thermowell transfers the heat to the temperature element. Depending upon the element type, the fluid temperature can be known. So Thermowell protects the temperature element against harsh conditions and process fluid. It enables removal of the temperature element for replacement, repair, or testing without affecting the process system. Generally, thermowells are provided with all-temperature Elements like RTD or Thermocouple or temperature gauge. A few exceptions would be bearing RTD, skin type thermocouple, air duct thermometer, etc where thermowell is not applicable / required. When the thermowell assembly is inserted into the pipe, it is subjected to vibration. This vibration is caused by vortices to be generated alternately on either side of the thermowell. The...

TILI Automation

Search This Blog