Effects of changing vapor phase conditions on radiation-based continuous level measurement

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Author: G. Bowers
Date: Oct. 2015
Publisher: Gulf Publishing Co.
Document Type: Article
Length: 870 words
Lexile Measure: 1390L

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Byline: Bowers, G.

Radiation-based continuous level gauges provide highly reliable measurements because no part of the instrument system is exposed to the process fluid, and they do not require penetration into the process vessel. To ensure accurate and repeatable measurement, users should carefully consider operating conditions inside the vessel. This study addresses the effects of a dynamic vapor space, where the atmosphere above the process fluid changes due to a reaction of process fluids and/or changes in temperature and pressure.

Calibration of any radiation-based measurement system requires referencing the system at known process conditions. For continuous level applications, this means referencing the system at known process levels within the measurement span. The best practice procedure is to acquire references at 10% increments of the measurement span at operating conditions. Often, this procedure is not achievable due to a limited ability to alter the process level during operation.

Measuring vapor conditions

The effects of the vapor space on the performance of the system are often overlooked. If the system is calibrated under conditions that do not reproduce the same vapor conditions (specifically vapor density) present during vessel operations, it can then be expected that the system will have an inherent systematic error.

A specific example of such an operating process is ammonia storage tanks. Liquid ammonia storage utilizes...

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Gale Document Number: GALE|A433370075