Vibration n Float Level Switch Vibration n Float Level Switch.pptx
- 3. MEASUREMENT Radar level instruments measure the distance from the transmitter (located at some high point) to the surface of a process material located farther below in much the same way as ultrasonic transmitters – by measuring the time-of-flight of a traveling wave. Radar • Radio / electromagnetic waves Ultrasonic • Sound / mechanical vibrations waves Guide Radar • guide the electromagnetic waves
- 4. HOW IT WORK • The time it takes for the instrument’s signal to leave the antenna, travel to the product, and return to the antenna is calculated into distance. • The instrument is spanned according to the distance the 100% and 0% points within the vessel are from its reference point. • The measured distance can then be converted into the end user’s desired engineering unit and viewed on the head of the instrument or remote display. 100% 0%
- 5. PROCESS CONDITIONS How do process conditions affect the reliability and accuracy of process level transmitters ? • density (specific gravity)? • dielectric constant? • conductivity? • temperature? • pressure? • vacuum? • agitation? • vapors and condensation? • dust and build up? • internal structures?
- 7. RADAR TECHNOLOGY – HOW IT WORKS Radar is a time of flight measurement. • microwave energy is transmitted by the radar. • the microwave energy is reflected off the product surface • the radar sensor receives the microwave energy. • the time from transmitting to receiving the microwave energy is measured. • the time is converted to a distance measurement and then eventually a level.
- 8. FUNCTION OF AN ANTENNA Signal focusing • reduction of the antenna ringing • optimization of the beam Signal amplification • focusing of the emitted signal • amplification of the receipt signal Signal orientation • point at the product surface • minimization of
- 9. RADAR TECHNOLOGY – WHY USE IT? Radar level measurement • top mounted • solids and liquids applications • non-contact Radar is virtually unaffected by the following process conditions: • temperature • pressure and vacuum • conductivity • dielectric constant (dk) • specific gravity • vapor, steam, dust or air movement • build up (depends on radar design)
- 10. RADAR TECHNOLOGY – CHOICE OF FREQUENCY radar wavelength = speed of light / frequency l = c / f Frequency 6.3 GHz wavelength l = 47.5 mm Frequency 26 GHz wavelength l = 11.5 mm High frequency: shorter wavelength narrower beam angle more focused signal ability to measure smaller vessels with more flexible mounting 47.5mm 11.5mm Low frequency: longer wavelength wider beam angle less focused signal ability to measure in vessels with difficult application variables
- 11. RADAR TECHNOLOGY – FOCUSING OF FREQUENCY 5 GHz 10 GHz Frequency Comparison of horn diameters that produce the same beam angle (A shorter wavelength means a smaller antenna for the same beam angle) 20 GHz 15 GHz 25 GHz Focusing at 6.3 GHz: Horn size Beam angle 3“ 38° 4“ 33° 6" 21° 10“ 15° Focusing at 26 GHz: Horn size Beam angle 1.5" 22° 2“ 18° 3“ 10° 4“ 8° 30 GHz 6.3 GHz 26 GHz