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Ultrasonic for methanol

Created by: PILearner at: 2/21/2014 12:57 PM (4 Replies)

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2/21/2014 12:57 PM	Rate (0)
PILearner Posts: 80 Rating: (1)	Can we use Ultrasonic based level measuring device for industrial grade methanol?
PILearner Posts: 80 Rating: (1)
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2/21/2014 2:40 PM	Rate (1)
Levelmans Bronze Member Joined: 12/13/2012 Last visit: 1/16/2019 Posts: 124 Rating: (45)	Dear PILeaner , generally, ultrasonic is not useable for a medium with a gaseous atmosphere. The speed of sound in a ambient atmosphere will be around 344 m/sec. This speedvalueis the basis for the calculation of themeasurementitself. In a non-ambient atmosphere, the speed of sound will be differnet to this value and we would get a drift in the measurement reading. For the microwave of a radar device, the atmosphere will have no influence to the reading, we also can measure in a vakuum here. For me, a radar devicewill bethe first choice for Methanol. Do you have some additional informations about the measurement , like the range, theprocess connectionect . ? The details would be needed to provide you a useable radar unit here. Hope this helps. Best Regards Levalmans

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2/21/2014 3:59 PM	Rate (0)
PILearner Posts: 80 Rating: (1)	Tank / Vessel Information: Type: Storage Height: 10 meter width/diamter: 5 m Tank Top: Closed and Flat Tank bottom: Flat Measurement Type: Continous Level Material being Measured: Methanol ( Horizontal Storage Tank) Material being measured: Formalin (Vertical Storage tank) Material Temperature and Pressure : upto 50°C Atmosphere : Air Power available: 24 V DC Outputs required : 4-20 ma Communciation: HART/ 4-20 ma
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2/24/2014 9:54 AM	Rate (0)
Levelmans Bronze Member Joined: 12/13/2012 Last visit: 1/16/2019 Posts: 124 Rating: (45)	Dear PILeaner , I suggest to go for the radarLR250 with 3 " or better 4 " horn antenna. SITRANS LR250 is a 2-wire, 25 GHz pulse radar level transmitter for continuous monitoring of liquids and slurries in storage and process vessels including high temperature and pressure, to a range of 20 m (66 ft). Please find the link for to the LR250 for further informations. https://www.automation.siemens.com/mcms/infocenter/dokumentencenter/sc/pi/InfocenterLanguagePacks/Catalog%20sheet%20SITRANS%20LR250%20Horn%20antenna/sitransl_LR250_FI01en.pdf With best regards Levelman

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2/26/2014 2:36 AM	Rate (0)
danw Gold Expert Joined: 3/28/2010 Last visit: 10/2/2023 Posts: 978 Rating: (199)	Note: not all the posts in this thread appeared when I first opened it and responded. Levelmans had already posted much the same answer as I did, but his post did not appear for some reason. -------------------- Ultrasonic measurement depends on the velocity of the energy "ping" through the medium. Reliable ultrasonic measurement depends upon a constant sonic velocity. But the sonic velocity changes depending on the medium. If the concentration of methanol in air or methanol in nitrogen in the vapor blanket through which the energy ping shoots is not constant, then you will have continual error due to the shift in velocity. Most tanks with chemicals are not open to atmosphere for a variety of reasons, and those tanks have venting to allow 'medium' to enter the tank when the liquid is drained to prevent a vacuum from forming which could collapse the tank. The vent might allow air or nitrogen into the tank which mixes with the vapor already there. So the question is, does the vapor blanket in your methanol tank maintain a constant concentration of methanol in whatever it mixes with when venting occurs? It probably does not. Radar, on the other hand, is not affected by the vapor blanket above the liquid (with the exception of ammonia which eats radar waves for breakfast, lunch and supper). If there's reasonable probability of a changing atmosphere above the liquid that wil cause a corresponding shift in sonic velocity with a corresponding error in measurement, use another technology. Hydrostatic head pressure (differential pressure) is another alternative for tanks that always have the same material.
	Last edited by: danw at: 2/26/2014 4:20 AM
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